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Compose
a 300
–
word (minimum) essay on the topic below. Essays must be double
–
spaced and use APA
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style in
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text citations to reference ideas or quotes that are not your own. You must include a separate
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What would happen to the economy and our buying habits if the hidden mineral extraction costs
associated with environmental damage due to mining, processing, use, and disposal were included in
the market prices paid by consumers for products containing tho
se minerals?
How would it change the way mining companies and manufacturers did business?
Could that help to create a more sustainable society? Explain.
You should cite and quote from assigned readings, AVP’s, videos, and module activities to s
upport the
ideas in your essay.
12
ch,13 14
most of the essay stuff comes from CH14
Compose a 300
–
word (minimum) essay on the topic below. Essays must be double
–
spaced and use APA
–
style in
–
text citations to reference ideas or quotes that are not your own. You must include a separate
bibliography.
What would happen to the economy and our buying habits if the hidden mineral extraction costs
associated with environmental damage due to mining, processing, use, and disposal were included in
the market prices paid by consumers for products containing tho
se minerals?
How would it change the way mining companies and manufacturers did business?
Could that help to create a more sustainable society? Explain.
You should cite and quote from assigned readings, AVP’s, videos, and module activities to s
upport the
ideas in your essay.
12
ch,13 14
most of the essay stuff comes from CH14
Compose a 300-word (minimum) essay on the topic below. Essays must be double-spaced and use APA-
style in-text citations to reference ideas or quotes that are not your own. You must include a separate
bibliography.
What would happen to the economy and our buying habits if the hidden mineral extraction costs
associated with environmental damage due to mining, processing, use, and disposal were included in
the market prices paid by consumers for products containing those minerals?
How would it change the way mining companies and manufacturers did business?
Could that help to create a more sustainable society? Explain.
You should cite and quote from assigned readings, AVP’s, videos, and module activities to support the
ideas in your essay.
12ch,13 14 most of the essay stuff comes from CH14
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20th Edition
12.1aFood Security and Food Insecurity
Food security
is the condition under which people have access to enough safe and nutritious food for a healthy and active lifestyle. More than 1 billion people work in agriculture to produce food on about 38% of the earth’s ice-free land. They produce more than enough food to meet the basic nutritional needs of every person on the earth. Despite this food surplus, one of every nine people in the world—about 815 million in all—is not getting enough to eat. These people face
food insecurity
by having to live with chronic hunger and poor nutrition that threaten their ability to lead healthy and active lifestyles. About 98% of the people facing food insecurity live in less developed countries, and 60% of them are women. In the United States, about 41 million people (13 million of them children under age 5) faced food insecurity in 2017.
Most agricultural experts agree that the root cause of food insecurity is poverty, which prevents poor people from growing or buying enough nutritious food to live healthy and active lives. This is not surprising given that in 2018, nearly 28% (2.1 billion) of the world’s people, struggled to live on the equivalent of $3.10 a day and 760 million people struggled to live on the equivalent of less than $1.90 a day, according to the World Bank and the Global Basic Income Foundation. Other obstacles to food security are war, corruption, bad weather (such as prolonged drought, flooding, and heat waves), climate change, and the harmful environmental effects of modern industrialized agriculture.
Each day, there are about 249,000 more people at the world’s dinner tables and many of them will have little or no food on their plates. By 2050, there will likely be at least 2.3 billion more people to feed. Most of these newcomers will be born in the major cities of less-developed countries. A critical question is how will we feed the projected 9.9 billion people in 2050 without causing serious harm to the environment? We explore possible answers to this question throughout this chapter.
12.1bChronic Hunger and Malnutrition
To maintain good health and resist disease, individuals need large amounts of macronutrients (such as carbohydrates, proteins, and fats) and smaller amounts of micronutrients—vitamins, such as A, B, C, and E, and minerals, such as iron, iodine, and calcium.
People who cannot grow or buy enough food to meet their basic energy needs suffer from
chronic undernutrition
, or
hunger
, a condition in which they do not get enough protein and key vitamins and minerals. This can weaken them, make them more vulnerable to disease, hinder the normal physical and mental development of children, and threaten their ability to lead healthy and productive lives. Most of the world’s hungry people can afford only a low-protein, high-carbohydrate, vegetarian diet consisting mostly of grains such as wheat, rice, and corn. In other words, they live low on the food chain (
Figure 12.2
).
Figure 12.2
The poor cannot afford to eat meat and, in order to survive, eat further down the food chain on a diet of grain.
Perhaps the worst form of food shortage is
famine
, which occurs when there is a severe shortage of food in an area. This can result in mass starvation, many deaths, economic chaos, and social disruption. Famines are usually caused by crop failures from drought, flooding, war, and other catastrophic events.
In more-developed countries, many people have a diet that is heavy on cheap food loaded with fats, sugar, and salt. These individuals often suffer from
chronic malnutrition
, a condition in which they do not get enough protein and other key nutrients. This can weaken them, make them more vulnerable to disease, and hinder the normal physical and mental development of children.
According to the United Nations Food and Agriculture Organization (FAO), in 2018 there were about 815 million chronically undernourished and malnourished people in the world (
Figure 12.3
). According to the FAO, at least 3.1 million children younger than age 5 died from chronic hunger and malnutrition in 2015 (the latest year for which data are available). Globally, the number and percentage of people suffering from chronic hunger has been declining since 1992 (
Figure 12.4
) but there is still a long way to go. In some areas of the world, the news is not so good. One of every four people living south of the Sahara Desert (sub-Saharan Africa) is undernourished.
Figure 12.3
One of every three children younger than age 5 in less-developed countries, such as this starving child in Bangladesh, suffers from severe malnutrition caused by a lack of calories and protein.
Rowan Gillson/Design Pics/Superstock
Figure 12.4
The number and percentage of people in less-developed countries that suffer from undernutrition and hunger have each been declining.
(Compiled by the authors using data from U.S. Department of Agriculture, UN Food and Agriculture Organization, and Earth Policy Institute.
12.1cLack of Vitamins and Minerals
About 2 billion people, most of them in less-developed countries, suffer from a deficiency of one or more vitamins and minerals, usually vitamin A, iron, and iodine. According to the World Health Organization (WHO), at least 250,000 children younger than age 6, most of them in less-developed countries, go blind every year from a lack of vitamin A. Within a year, more than half of them die. Providing children with adequate vitamin A could save at least 130,000 lives per year.
Having too little iron (Fe) in the blood is a condition called anemia. It causes fatigue, makes infection more likely, and increases a woman’s chances of dying from hemorrhage in childbirth. According to the WHO, about 30% the world’s people—most of them women and children in less-developed countries—suffer from iron deficiency. By 2050, iron deficiency could affect the health of 1.4 billion people.
The chemical element iodine (I) is essential for proper functioning of the thyroid gland, which produces hormones that control the body’s rate of metabolism. Chronic lack of iodine can cause stunted growth, mental retardation, and goiter—a severely swollen thyroid gland that can lead to deafness (
Figure 12.5
). According to the United Nations (UN), some 600 million people (almost twice the current U.S. population) suffer from goiter, most of them in less-developed countries. Every year, 19 million babies are at risk of permanent brain damage due to a lack of iodine in pregnancy and early childhood, according to a 2018 UN report. The FAO and the WHO estimate that eliminating this serious health problem by adding traces of iodine to salt would cost the equivalent of only 2 to 3 cents per year for every person in the world.
Figure 12.5
This woman suffers from goiter, an enlargement of the thyroid gland, caused by a lack of iodine in her diet.
Mike Goldwater/Alamy Stock Photo
12.1dHealth Problems from Too Much Food
Overnutrition
occurs when food energy intake exceeds energy use and causes excess body fat. Too many calories, too little exercise, or both can cause overnutrition.
People who are underfed and underweight and those who are overfed and overweight face similar health problems: lower life expectancy, greater susceptibility to disease and illness, and lower productivity and life quality
We live in a world where, according to the World Health Organization (WHO), about 815 million people face health problems because they do not get enough nutritious food to eat and another 2.1 billion people (up from 857 million in 1980) have health problems caused mostly by eating too much sugar, fat, and salt. This, along with inactive lifestyles, can cause them to become overweight or obese.
In order, the countries with the most overweight and obese people are the United States, China, India, Russia, and Brazil. According to a study by the McKinsey Global Institute, the resulting healthcare and lost-productivity costs are about $2 trillion a year—more than the combined annual global costs of war, terrorism, and armed violence.
72%
Percentage of U.S. adults over age 20 who are obese (38%) or overweight (34%)
According to the U.S. Centers for Disease Control and Prevention (CDC), about 72% of adults over age 20 and 33% of all children in the United States are overweight or obese (
Figure 12.6
). A study by Columbia University and the Robert Wood Johnson Foundation found that obesity plays an important role in nearly one in five deaths in the United States from heart disease, stroke, type 2 diabetes, and some forms of cancer.
Figure 12.6
Almost 3 of every 4 adults over age 20 in the United States are overweight or obese.
Surachai/ Shutterstock.com
These three systems depend on a small number of plant and animal species. Of the estimated 50,000 plant species that people can eat, about 90% of the world’s food calories come from only 14 of them. At least half the world’s people survive primarily by eating rice, wheat, and corn because they cannot afford meat. Only a few species of mammals and fish provide most of the world’s meat and seafood.
Such food specialization puts us in a vulnerable position. If any of the small number of crop strains, livestock breeds, and fish and shellfish species that we depend on were to become depleted, the consequences would be dire. Plant or livestock diseases, environmental degradation, and climate change could cause such depletion. This food specialization violates the biodiversity principle of sustainability, which calls for depending on a variety of food sources as an ecological insurance policy against changing environmental conditions.
Despite such genetic vulnerability, since 1960, there has been a staggering increase in global food production from all three of the major food production systems. Three major technological advances have been especially important:
1. the development of
irrigation
, a mix of methods by which water is supplied to crops by artificial means;
2.
synthetic fertilizers
—manufactured chemicals that contain nutrients such as nitrogen, phosphorus, potassium, calcium, and several others; and
3.
synthetic pesticides
—chemicals manufactured to kill or control populations of organisms that interfere with crop production.
4. 12.2bIndustrialized Agriculture
5.
Industrialized agriculture
, or
high-input agriculture
, uses motorized equipment (see
chapter-opening photo
) along with large amounts of financial capital, fossil fuels, water, commercial inorganic fertilizers, and pesticides. Industrialized agriculture produces a single crop at a time on a plot of land, a practice known as
monoculture
(
Figure 12.7
). The major goal of industrialized agriculture is to increase each crop’s
yield
—the amount of food produced per unit of land. Industrialized agriculture is practiced on 25% of all cropland, mostly in more-developed countries, and produces about 80% of the world’s food.
6. Figure 12.7
7. Monoculture soybean field.
8.
9.
Oticki/ Shutterstock.com
Plantation agriculture is a form of industrialized agriculture used primarily in less-developed tropical countries. It involves growing cash crops such as bananas, coffee, vegetables, soybeans (mostly to feed livestock; see
Figure 1.6
), sugarcane (to produce sugar and ethanol fuel), and palm oil (to produce cooking oil and biodiesel fuel). These crops are grown on large monoculture plantations, mostly for export to more-developed countries12.2cTraditional Agriculture
Traditional, low-input agriculture provides about 20% of the world’s food crops on about 75% of its cultivated land, mostly in less-developed countries. It takes two basic forms.
Traditional subsistence agriculture
combines energy from the sun with the labor of humans (
Figure 12.8
) and draft animals to produce enough crops for a farm family’s survival, with little left over to sell or store as a reserve for hard times. In
traditional intensive agriculture
, farmers try to obtain higher crop yields by increasing their inputs of human and draft animal labor, animal manure for fertilizer, and water. With good weather, farmers can produce enough food to feed their families and have some left over to sell for income.
Figure 12.8
Traditional subsistence agriculture in India.
CRS PHOTO/ Shutterstock.com
Some traditional farmers focus on cultivating a single crop, but many grow several crops on the same plot simultaneously, a practice known as
polyculture
. This method relies on solar energy and natural fertilizers such as animal manure. The various crops mature at different times. This provides food year-round and keeps the topsoil covered to reduce erosion from wind and water. Polyculture also lessens the need for fertilizer and water because root systems at different depths in the soil capture nutrients and moisture efficiently. In addition, weeds have trouble competing with the multitude and density of crop plants, and this crop diversity reduces the chance of losing most or all of the year’s food supply to pests, bad weather, and other misfortunes.
One type of polyculture is known as slash-and-burn agriculture (
Figure 12.9
). This type of subsistence agriculture involves burning and clearing small plots in tropical forests, growing a variety of crops for a few years until the soil is depleted of nutrients, and then shifting to other plots to begin the process again. In parts of South America and Africa, some traditional farmers grow as many as 20 different crops together on small cleared plots.
Figure 12.9
Poor settlers in Peru have cleared and burned this small plot in a tropical rain forest in the Amazon and planted it with seedlings to grow food for their survival.
Dr. Morley Read/ Shutterstock.com
Polyculture is an application of the biodiversity principle of sustainability. Crop diversity helps protect and replenish the soil and reduces the chance of losing most or all of the year’s food supply to pests, bad weather, and other misfortunes. Research shows that, on average, low-input polyculture produces higher average yields than high-input industrialized monoculture, while using less energy and fewer resources, and provides more food security for small landowners. For example, ecologists Peter Reich and David Tilman found that carefully controlled polyculture plots with 16 different species of plants consistently out-produced plots with 9, 4, or only 1 type of plant species.
Learning from Nature
Scientists are studying natural biodiversity to learn how to grow crops using polyculture. The idea is to grow stable crop systems, less vulnerable to environmental threats than monoculture crops are, and to increase yields.
10.
11. 12.2dOrganic Agriculture
12. A fast-growing sector of U.S. and world food production is
organic agriculture
. Organic crops are grown without the use of synthetic pesticides, synthetic inorganic fertilizers, or genetically engineered seed varieties. Animals are raised on 100% organic feed without the use of antibiotics or growth hormones. Organic food sales have more than tripled since 2000.
13. In the United States, by law, a label of 100 percent organic (or USDA Certified Organic) means that a product is produced only by organic methods and contains all organic ingredients. Products labeled “organic” must contain at least 95% organic ingredients. Those labeled made with organic ingredients must contain at least 70% organic ingredients. The word natural has no requirement for organic ingredients. In 2018, 7% of the fruit, 1
1%
of the vegetables, 15% of the frozen fruit, and 5% of the frozen vegetables sold in the United States were organic. In 2018, the U.S. Department of Agriculture (USDA) called the U.S. food supply “among the safest in the world” with more than 99% of the samples tested having pesticide residues well below the levels established by the EPA.
Figure 12.10
compares organic agriculture with industrialized agriculture.
14. Figure 12.10
15. Major differences between industrialized agriculture and organic agriculture.
16.
17.
18.
Left top:
B Brown/ Shutterstock.com
. Left center: ZoranOrcik/ Shutterstock.com. Left bottom: Art Konovalov/ Shutterstock.com. Right top: Noam Armonn/ Shutterstock.com. Right center: Varina C/ Shutterstock.com and Jay Patel/ Shutterstock.com. Right bottom: Adisa/ Shutterstock.com.
12.2eGreen Revolutions Have Increased Crop Yields
Farmers have two ways to produce more food: farm more land or increase yields from existing cropland. Since 1950, most of the dramatic increase in global grain production has been the result of increasing crop yields through industrialized agriculture.
This process, called the
green revolution
, involves three steps. First, develop and plant monocultures of selectively bred or genetically engineered high-yield varieties of key crops such as rice, wheat, and corn. Second, produce high yields by using large inputs of water, synthetic inorganic fertilizers, and pesticides. Third, increase the number of crops grown per year on a plot of land.
In the first green revolution, which occurred between 1950 and 1970, this high-input approach dramatically raised crop yields in most of the world’s more-developed countries, especially the United States (see the Case Study that follows).
In the second green revolution, which began in 1967, fast-growing varieties of rice and wheat, specially bred for tropical and subtropical climates, were introduced into middle-income, less-developed countries such as India, China, and Brazil. Producing more food on less land in such countries has helped protect biodiversity by preserving large areas of forests, grasslands, and wetlands that might otherwise be used for farming.
Largely because of the two green revolutions, between 1950 and 2018, world grain production (
Figure 12.11
, left) and per capita grain production (Figure 12.11, right) grew dramatically. In 2018, the world’s five largest grain-producing countries—the United States, China, the European Union, Brazil, and India—produced two-thirds of the world’s grains. However, according to the U.S. Department of Agriculture (USDA), the global rate of growth in grain crop yields has slowed from an average of 2.2% per decade before 1990 to 1.2% per decade since then.
Figure 12.11
Growth in worldwide grain production (left) of wheat, corn, and rice, and in per capita grain production (right) between 1950 and 2018.
Critical Thinking:
1. Why do you think grain production per capita has grown less consistently than total grain production?
(Compiled by the authors using data from U.S. Department of Agriculture, Worldwatch Institute, UN Food and Agriculture Organization, and Earth Policy Institute.)
People directly consume about half of the world’s grain production. Most of the rest is fed to livestock and is consumed by people who can afford to eat meat and meat products.
China faces the daunting challenge of how to feed 18% of the world’s population with less than 10% of the world’s cropland. A growing percent of its population is affluent enough to eat meat. To help feed its people Chinese companies are buying land and food companies in other countries such as the United States, Ukraine, Chile, and Tanzania.
An important factor in expanded industrialized crop production has been the use of
farm subsidies
, or government payments and tax breaks intended to help farmers stay in business and increase their yields. In the United States, most subsidies go to corporate farming operations for raising corn, wheat, soybeans, and cotton on an industrial scale. U.S. government records show that in recent years, nearly 74% of all subsidies went to just 10% of all U.S. farmers.
Case Study
Industrialized Food Production in the United States
In the United States, industrialized farming has evolved into agribusinesses. A few giant multinational corporations increasingly control the growing, processing, distribution, and sale of food in U.S. and global markets. In total annual sales, agriculture is bigger than the country’s automotive, steel, and housing industries combined. Because of advances in technology, the numbers of U.S. farms and farmers have dropped sharply as production has risen. As a result, the average U.S. farmer now feeds 129 people compared to 19 people in the 1940s.
1%
Percentage of the U.S. workforce who are farmers—down from 18% in 1910
Since 1960, U.S. industrialized agriculture has more than doubled the yields of key crops such as wheat, corn, and soybeans without the need for cultivating more land. Such yield increases have saved large areas of U.S. forests, grasslands, and wetlands from being converted to farmland.
Because of the efficiency of U.S. agriculture, Americans spend the lowest percentage of disposable income in the world—an average of 10% on food. By contrast, low-income people in less-developed countries typically spend 50–70% of their income on food, according to the USDA and FAO.
However, because of a number of hidden costs related to food production and consumption, most American consumers are unaware that their actual food costs are much higher than the market prices they pay. Such hidden costs include the costs of pollution and environmental degradation, higher health insurance bills related to the harmful health effects of industrialized agriculture, and government farm subsidies.
12.2fGenetic Revolutions: Crossbreeding and Genetic Engineering
For centuries, farmers and scientists have used crossbreeding to develop genetically improved varieties of crops and livestock animals. Through artificial selection, farmers have developed genetically improved varieties of crops (see
Figure 4.18
) and livestock animals. For example, a tasty but small species of tomato might be crossbred with a larger species of tomato to produce a larger, tasty tomato species. Such selective breeding in this first gene revolution has yielded amazing results. For example, ancient ears of corn were about the size of your little finger, and wild tomatoes were once the size of grapes, but most of the large varieties used now were selectively bred.
Traditional crossbreeding is a slow process. It often takes 15 years or more to produce a commercially valuable new crop variety and it can combine traits only from species that are genetically similar. Typically, resulting varieties remain useful for only 5 to 10 years before pests and diseases reduce their yields. However, important advances are still being made with this method.
Today, a second gene revolution is taking place. Scientists and engineers are using genetic engineering to develop genetically modified (GM) strains of crops and livestock animals. They use a process called gene splicing to add, delete, or change segments of an organism’s DNA (see
Figure 2.9
). The goal of this process is to add desirable traits or eliminate undesirable ones by transferring genes between species that would not normally interbreed in nature. The resulting organisms are called genetically modified organisms (GMOs).
Developing a new crop variety through genetic engineering takes about half as long as traditional crossbreeding and usually costs less. According to the U.S. Department of Agriculture (USDA), at least 80% of the food products on U.S. supermarket shelves contain some form of genetically modified food or ingredients and that percentage is growing.
80%
Percentage of food products sold in the United States that contain some form of genetically modified food or ingredients
A new generation of genetically altered crops is based on snipping or editing existing genes at precise locations instead of transferring genes between species. The new CRISPR gene-editing technique allows scientists to achieve desired effects by altering a plant’s own DNA without inserting new genes. Crops that are genetically engineered in this way can be brought to the market faster and more cheaply than traditionally genetically engineered crops.
12.2gGrowing Meat Consumption
Meat and animal products such as eggs and milk are sources of high-quality protein and represent the world’s second major food-producing system. According to the FAO, global meat production grew more than six-fold between 1950 and 2018. Since 1974, total global meat consumption has more than doubled according to the FAO and is likely to more than double again by 2050 as incomes rise and millions of people in rapidly developing countries consume more meat and meat products.
About half of the world’s meat comes from livestock grazing on grass in unfenced rangelands and enclosed pastures. The other half is produced through an industrialized factory farm system. This involves raising large numbers of animals bred to gain weight quickly, mostly in feedlots (
Figure 12.12
) or in crowded pens and cages in huge buildings. These operations are called concentrated animal feeding operations (CAFOs), or factory farms (
Figure 12.13
). In CAFOs, the animals are fed grain, soybeans, fishmeal, or fish oil, and some of this feed is doctored with growth hormones and antibiotics to accelerate livestock growth. Because of the crowding and runoff of animal wastes from CAFOs, these operations have harmful impacts on the air and water, which we examine later in this chapter.
Figure 12.12
Industrialized beef production: On this cattle feedlot in Arizona, thousands of cattle are fattened on grain for a few months before being slaughtered.
PETE MCBRIDE/National Geographic Creative/National Geographic Image Collection
Figure 12.13
Concentrated chicken feeding operation in Iowa (USA). Such operations can house up to 100,000 chickens.
Scott Sinklier/AgStock Images/Terra/Corbis
As a country’s income grows, more of its people tend to eat more meat, much of it produced by feeding grain to livestock. The resulting increased demand for grain, often accompanied by a loss of cropland to urban development, can lead to greater reliance on grain imports. China and India are following this trend as they become more industrialized and urbanized.
12.2hFish and Shellfish Production
The world’s third major food-producing system consists of fisheries and aquaculture. A fishery is a concentration of a particular aquatic species suitable for commercial harvesting in a given ocean area or inland body of water. Industrial fishing fleets use a variety of methods (
Figure 11.8
) to harvest most of the world’s marine catch of wild fish. Fish and shellfish are also produced through
aquaculture
or
fish farming
(
Figure 12.14
). It involves raising fish in freshwater ponds, lakes, reservoirs, and rice paddies, and in underwater cages in coastal and deeper ocean waters.
Figure 12.14
Aquaculture: Shrimp farms on the southern coast of Thailand.
Puwanai/ Shutterstock.com
Aquaculture is the world’s fastest growing type of food production. Between 1950 and 2016, global seafood production of wild and farmed fish increased more than ninefold, while the global wild catch leveled off and declined. In 2016, aquaculture accounted for 47% of the world’s fish and shellfish production (compared to 26% in 2000), and the rest were caught mostly by industrial fishing fleets (
Figure 12.15
). According to the Woods Hole Fisheries Service, about 90% of the world’s commercial ocean fisheries are being harvested at full capacity (61%) or are overfished (29%).
Figure 12.15
World seafood production, including both wild catch (marine and inland) and aquaculture, grew between 1950 and 2015, with the wild catch generally leveling off since 1996 and aquaculture production rising sharply since 1990.
Data Analysis:
1. In about what year did aquaculture surpass the 1980 wild catch?
(Compiled by the authors using data from UN Food and Agriculture Organization, Worldwatch Institute, and Earth Policy Institute.)
90%
Percentage of the world’s ocean fisheries that are overfished or harvested at full capacity
Asia accounts for about 88% of the world’s annual aquaculture production, with China accounting for about 60%. Most of the world’s aquaculture involves raising species that feed on algae or other plants—mainly carp in China, catfish in the United States, and tilapia and shellfish in a number of countries. However, the farming of meat-eating species such as shrimp and salmon is growing rapidly, especially in more-developed countries. Such species are often fed fishmeal and fish oil produced from other fish and their wastes.
12.3a
Energy Use in Industrialized Food Production
The industrialization of food production and increased crop yields have been made possible by use of fossil fuels—mostly oil and natural gas—to run farm machinery and fishing vessels, to pump irrigation water for crops, and to produce synthetic pesticides and synthetic inorganic fertilizers. Fossil fuels are also used to process food and transport it long distances within and between countries. Altogether, food production accounts for about 17% of all of the energy used in the United States, more than any other industry. Burning such large quantities of fossil fuels pollutes the air and water and contributes to climate change.
When we consider the energy used to grow, store, process, package, transport, refrigerate, and cook all plant and animal food, it takes about 10 units of fossil fuel energy to put 1 unit of food energy on the table in the United States. In addition, according to a study led by ecological economist Peter Tyedmers, the world’s fishing fleets use about 12.5 units of energy to put 1 unit of food energy from seafood on the table. In other words, today’s food production systems operate with a large net energy loss.
On the other hand, the amount of energy per calorie used to produce crops in the United States has declined by about 50% since the 1970s. One factor in this decline is that the amount of energy used to produce synthetic nitrogen fertilizer has dropped sharply. Another reason for the decline is the rising use of conservation tillage or no-till farming (see
Core Case Study
), which sharply reduces energy use and the harmful environmental effects of plowing.
12.3b
Environmental Impact of Industrialized Agriculture
Industrialized food production has allowed farmers to use less land to produce more food. This has reduced the need to convert forests and grasslands to cropland and thereby destroying the wildlife habitats provided by these ecosystems.
However, many analysts point out that industrialized agriculture has greater overall harmful environmental impacts (Figure 12.16) than any other human activity. These impacts may limit future food production.
Figure 12.16
Food production has a number of harmful environmental effects.
Critical Thinking:
Which item in each of these categories do you think is the most harmful? Why?
An illustration shows information about Food Production within a box which is labeled as, “Natural Capital Degradation.” Five photos are shown, namely, the first photo shows a heavy equipment which is used for harvesting a land where crops are ready for harvesting and labeled as Biodiversity Loss, the second photo shows an unfertile land labeled as soil, the third photo shows a river flowing and vegetation around and labeled as water, the fourth photo shows several cattle being fed and labeled as Air Pollution, and the fifth photo shows jet flying water and labeled as human health. The text below the first photo reads, “Conversion of grasslands, forests, and wetlands to crops or rangeland, fish kills from pesticide runoff, killing of wild predators to protect livestock, and loss of agrobiodiversity replaced by monoculture strains.” The text below the second photo reads, “Erosion, loss of fertility, Salinization, waterlogging, and Desertification.” The text below the third photo reads, “Aquifer depletion, increased runoff, sediment pollution, and flooding from cleared land, pollution from pesticides, Algal blooms and fish kills caused by runoff of fertilizers and farm wastes.” The text below the fourth photo reads, “Emissions of greenhouse gases CO2 from fossil fuel use, N2O from inorganic fertilizer use, and methane (CH4) from cattle, and other air pollutants from fossil fuel use and pesticide sprays.” The text below the fifth photo reads, “Nitrates in drinking water (blue baby), pesticide residues in water, food, and air, livestock waste in drinking and swimming water, and bacterial contamination of meat”Enlarge Image
Left: Orientaly/ Shutterstock.com. Left center: pacopi/ Shutterstock.com. Center: Tim McCabe/USDA Natural Resources Conservation Service. Right center: Mikhail Malyshev/ Shutterstock.com. Right: B Brown/ Shutterstock.com.
According to a study by 27 experts assembled by the United Nations Environment Programme (UNEP), agriculture uses massive amounts of the world’s resources and pollutes the air and water. It uses about 70% of the world’s freshwater removed from aquifers and surface waters, worldwide. It also produces about 60% of all water pollution, degrades and erodes topsoil, emits about 25% of the world’s greenhouse gas emissions, and uses about 38% of the world’s ice-free land.
As a result, many analysts view today’s industrialized agriculture as environmentally and economically unsustainable. However, proponents of industrialized agriculture argue that its benefits outweigh its harmful effects. Figure 12.17 lists the major advantages and disadvantages of industrialized agriculture.
Figure 12.17
Industrialized agriculture has advantages and disadvantages.
Critical Thinking:
Do you think that the advantages outweigh the disadvantages? Why or why not?
The advantages and disadvantages of industrialized agriculture are as follows. Advantages. Greatly increases yields. Efficiency helps preserve wildlife habitat. Can support local economies. Spurs improvements in agricultural technology. Disadvantages. Pollutes air. Pollutes water. Erodes topsoil. Plays large role in climate change.
Top: Orientaly/ Shutterstock.com; Bottom: B. Brown/ Shutterstock.com12.3c
Topsoil Erosion
Topsoil, is the fertile top layer of many soils (Figure 3.10). It is one of the most important components of the earth’s natural capital because all terrestrial life depends directly or indirectly on this potentially renewable resource. Topsoil stores and purifies water and supplies most of the nutrients needed for plant growth. It recycles these nutrients endlessly as long as they are not removed faster than natural processes replenish them. Organisms living in topsoil remove and store carbon dioxide from the atmosphere, thereby helping to control the earth’s climate as part of the carbon cycle. Thus, sustainable agriculture begins with sustaining topsoil.
A major environmental problem related to agriculture is soil erosion—the movement of soil components, especially surface litter and topsoil from one place to another by the actions of wind and water. Some topsoil erosion is natural, but much of it is caused by clearing forests and grasslands for agriculture, plowing the soil to plant new crops each year, and leaving the soil exposed during part of the year.
Flowing water, the largest cause of erosion, carries away particles of exposed topsoil that have been loosened by rainfall (Figure 12.18, left). Severe erosion of this type leads to the formation of gullies (Figure 12.18, right). Wind also loosens and blows particles of topsoil away, especially in areas with a dry climate and relatively flat and exposed land (Figure 12.19).
Figure 12.18
Natural capital degradation: Flowing water from rainfall is the leading cause of topsoil erosion as seen on this farm in the U.S. state of Tennessee (left). Severe water erosion can become gully erosion, which has damaged this cropland in western Iowa (right).
A figure shows two photos, one in the left and the other in the right. A photo on the left side shows vegetation which is slightly damaged due to the topsoil erosion caused due to the flow of running water. A photo on the right side shows vegetation and buildings at the back and a gully erosion is caused due to the water erosion and the entire cropland is damaged making a big pit in that area.Enlarge Image
Left: Tim McCabe/USDA Natural Resources Conservation Service. Right: © USDA Natural Resources Conservation Service.
Figure 12.19
Wind is an important cause of topsoil erosion in dry areas that are not covered by vegetation such as this bare crop field in the U.S. state of Iowa.
A photo shows a dry land or a bare land without any vegetation and a few houses behind it which are not clearly seen, due to top soil wind erosion.
Lynn Betts/USDA Natural Resources Conservation Service
In undisturbed, vegetated ecosystems, the roots of plants help anchor topsoil and prevent some erosion. However, topsoil can erode when soil-holding grasses, trees, and other vegetation are removed through activities such as farming, clear-cut logging (see Figure 10.7), and overgrazing (see Figure 10.11). A joint survey by the UNEP and the World Resources Institute indicated that topsoil is eroding faster than it forms on about one-third of the world’s cropland (Figure 12.20). Soil in the United States is eroding ten times faster than it is being replenished by natural processes. In India and China it is eroding 30 to 40 times faster.
Figure 12.20
Natural capital degradation: Topsoil erosion is a serious problem in some parts of the world.
Critical Thinking:
Can you see any geographical pattern associated with this problem?
An illustration shows the world map to describe serious concern, some concern, and stable or nonvegetative concern for topsoil erosion. Serious concern is shown by shading a few parts of southern North America, almost all parts of Central America, few parts of South America, Africa, southern and western Asia, Europe, and a small portion in Australia in one shade. Some concern is shown by shading a few parts of southern North America, few parts of South America, Africa, southern and western Asia, Europe, and a larger portion in Australia in another shade. The stable or nonvegetative concern is shown by leaving the northern portion of North America and eastern portion of Asia without shading. Few portions of South America, Africa, Asia, Europe, and Australia are also left without shading. The entire Greenland is left without shading.Enlarge Image
(Compiled by the authors using data from the U.N. Environment Programme and the World Resources Institute.)
Erosion of topsoil has three major harmful effects:
Loss of soil fertility through depletion of plant nutrients in topsoil (see Figure 3.12).
Water pollution in surface waters where eroded topsoil ends up as sediment, which can kill fish and shellfish and clog irrigation ditches, boat channels, reservoirs, and lakes. Pesticides in eroded sediment can be ingested by aquatic organisms and in some cases biomagnified in food webs (see
Figure 9.14
).
Release to the atmosphere of carbon stored in the soil as , which contributes to atmospheric warming and climate change.
Soil pollution is also a problem in some parts of the world. Some of the chemicals emitted into the atmosphere by industrial and power plants and by motor vehicles can pollute soil and irrigation water. Some pesticides can also contaminate soil. A recent study by China’s environment ministry estimated that 2.5% of the country’s cropland is too contaminated to grow food safely. China, with 18% of the world’s people and only 7% of the world’s arable land, cannot afford to lose 2.5% of its cropland.
12.3d
The Phosphate Crisis
The amount of food we produce through modern industrialized agriculture is heavily dependent on the use of phosphate-based fertilizers. However, the amount of phosphate available from mines is limited, which could at some point limit food production and affect the world’s economies. In addition, phosphate mining can disrupt the land and overload nearby water systems with excess phosphates.
Ways to deal with this problem include
Watering crops with wastewater that contains phosphates.
Reducing soil erosion so that more phosphorus is available for crops.
Applying fertilizer so that less of it is lost to water and wind erosion.
12.3e
Desertification
Drylands in regions with arid and semiarid climates occupy about 40% of the world’s land area and are home to some 2.5 billion people. A major threat to food security in some of these areas is desertification—the process in which the productive potential of topsoil falls by 10% or more because of a combination of prolonged drought and human activities that expose topsoil to erosion.
Desertification can be moderate (with a 10–25% drop in productivity), severe (with a drop of 25–50%), or very severe (with a drop of more than 50%, usually resulting in large gullies and sand dunes). Desertification decreases soil productivity but only in extreme cases does it lead to what we call a desert.
Over thousands of years, the earth’s deserts have expanded and contracted, primarily because of climate change. However, human uses of the land, especially for agricultural purposes, have increased desertification in some parts of the world. Such uses can involve clearing trees, plowing excessively, and overgrazing (Figure 10.11), which have left much topsoil bare and unprotected.
In the 1930s, much of the topsoil in several dry and windy regions of the Midwestern United States was lost because of a combination of poor cultivation practices and prolonged drought. The resulting severe wind erosion led to crop failures and to the formation of a barren dust bowl. Thousands of farmers had to abandon their degraded land and move to other parts of the United States.
Researchers at the Earth Policy Institute have warned that overgrazing, overplowing, and deforestation are creating two new dust bowls. One is in the central African Sahel, a vast savanna-like area south of the Sahara Desert. The other straddles northern China and southern Mongolia. The researchers reported that about 90% of China’s grasslands are degraded and suffering from desertification. Since 1950, more than 24,000 Chinese villages have been abandoned to spreading sands. Moreover, according to the Indian Space Research Organization, 24% of India’s land is threatened by desertification.
12.3f
Excessive Irrigation, Soil Salinization, and Waterlogging
Irrigation accounts for about 70% of the water that humanity uses. Currently, the 16% of the world’s cropland that is irrigated produces about 36% of the world’s food.
However, irrigation has a downside. Most irrigation water is a dilute solution of various salts, such as sodium chloride, that are picked up as the water flows over or through soil and rocks. Irrigation water that is not absorbed into the topsoil evaporates and leaves behind a thin crust of dissolved mineral salts in the topsoil. Repeated applications of irrigation water in dry climates can lead to an accumulation of salts in the upper soil layers—a soil degradation process called soil salinization. It stunts crop growth, lowers crop yields, and can eventually kill plants and ruin the land.
The FAO estimates that severe soil salinization has reduced yields on at least 10% of the world’s irrigated cropland, and that by 2020, 30% of the world’s arable (farmable) land will be salty. The most severe salinization occurs in China, India, Egypt, Pakistan, Mexico, Australia, and Iraq. According to the USDA, salinization reduces yields on about 30% of irrigated cropland in the United States, especially in western states (Figure 12.21).
Figure 12.21
Natural capital degradation: White alkaline salts have displaced crops that once grew on this heavily irrigated land in the U.S. state of Colorado.
A photo shows a fence to the left of which is a green vegetation and to the right is a dry land without any vegetation with white alkaline salt deposition.
USDA Natural Resources Conservation Service
Another problem with irrigation is waterlogging, in which water accumulates underground and gradually raises the water table. This can occur when farmers apply large amounts of irrigation water in an effort to reduce salinization by leaching salts deeper into the soil. Waterlogging lowers the productivity of crop plants and kills them after prolonged exposure because it deprives plants of the oxygen they need to survive. At least 10% of the world’s irrigated land suffers from this worsening problem, according to the FAO.
12.3g
Pollution, Climate Change, and Industrialized Agriculture
Some farmers contribute to pollution by over-fertilizing their fields. Globally, the use of fertilizers has grown 45-fold since 1940. Nitrates in fertilizer can also percolate down through the soil into aquifers where they can contaminate groundwater used for drinking. According to the FAO, fully one-third of all water pollution from the runoff of nitrogen and phosphorus is due to excessive use of synthetic fertilizers.
Agricultural activities also pollute the air. Clearing and burning forests to raise crops or livestock adds dust and smoke to the air. By applying fertilizer and pesticides, farmers emit particles and various chemicals into the air. Agriculture also accounts for about a third of all human-generated emissions of greenhouse gases—more than all of the greenhouse gases emitted by the world’s cars, trucks, ships, airplanes, and trains combined. These emissions warm the atmosphere and contribute to climate change, which can reduce crop productivity and food security.
12.3h
Food Production and Biodiversity Loss
Biodiversity and some ecosystem services are threatened when forests are cleared and when grasslands are plowed up and replaced with croplands. For example, one of the fastest-growing threats to world’s biodiversity is happening in Brazil. Large areas of tropical forest in its Amazon Basin and in cerrado—a huge tropical grassland region south of the Amazon Basin—are being burned or cleared for cattle ranches and for large plantations of soybeans grown for cattle feed. Biodiversity is threatened in these and many other areas because tropical forests and grasslands have much greater biodiversity than does agricultural land.
A related problem is the increasing loss of agrobiodiversity—the genetic variety of animal and plant species used on farms to produce food. Scientists estimate that since 1900, we have lost around 75% of the genetic diversity of agricultural crops. For example, India once planted 30,000 varieties of rice. Now more than 75% of its rice production comes in only 10 varieties. Soon most of its production might come from just one or two varieties. In the United States, about 97% of the food plant varieties available to farmers in the 1940s no longer exist, except perhaps in small amounts in seed banks and occasional home gardens.
Traditionally, farmers have saved seeds from year to year to save money and to have the ability to grow food in times of famine. Families in India and most other less-developed countries still do this, but in the United States, this tradition is disappearing as more farmers plant seeds for genetically engineered crops. Companies that sell these seeds have patents on them, forbid users to save them, and have successfully sued a number of farmers who saved and used such seeds.
Ecologists warn that farming practices that reduce biodiversity are rapidly shrinking the world’s genetic “library” of plant varieties, which are critical for increasing food yields through crossbreeding and genetic engineering. This failure to preserve agrobiodiversity is a serious violation of the biodiversity principle of sustainability that could reduce the sustainability of food production.
Efforts are being made to save individual plants and seed from endangered varieties of crops and wild plant species important to the world’s food supply. About 1,750 refrigerated seed banks store individual plants and seeds. They are also stored in agricultural research centers and botanical gardens scattered around the world.
However, power failures, fires, storms, and wars can cause irreversible losses of these stored plants and seeds. The world’s most secure seed bank is the underground Svalbard Global Seed Vault, also called “the doomsday seed vault,” carved into the Arctic permafrost on a frozen Norwegian arctic island near the North Pole (Figure 12.22). It is being stocked with duplicates of much of the world’s seed collections. By 2018, it stored more than a million seeds from all around the world and has a capacity for 2.5 billion seeds.
Figure 12.22
Svalbard Global Seed Vault.
A photo shows a room which has got a shelf with partitions comprising of sealed containers with seeds, which acts as a seed bank. A man carries a sealed container in his hand and is trying to find out a place for the container in the shelf.Enlarge Image
JIM RICHARDSON/National Geographic Image Colllection
However, a 2018 report by the Norwegian government warned that the entire seed collection is threatened by projected global warming that would increase the air temperature above the facility by about
by 2075. This increase in heat will thaw the protective surrounding permafrost and destroy the seeds. Rainfall will be more common and intense along with landslides and avalanches. During the last 4 to 5 decades, the air temperature above the vault has increased by 3 to , the permafrost has warmed, and avalanches in the area have increased. In 2017, water from partial melting of the surrounding permafrost penetrated into the vault, which was designed to be impenetrable. No seeds were damaged and the leaks have been repaired.
Another problem is that the seeds of many plants cannot be stored successfully in seed banks. In addition, stored seeds must be planted and germinated periodically and new seeds must be collected. Unless this is done, seed banks become seed morgues.
Connections
GM Crops and Organic Food Prices
The spread of GM crop genes by wind carrying pollen from field to field threatens the production of certified organic crops, which must be grown without such genes to be classified as organic. Organic farmers have to perform expensive tests to detect GMOs or take costly planting measures to prevent the spread of GMOs to their fields from nearby crop fields. This has forced some organic producers to raise their prices.
12.3i
Limits to Expanding Green Revolutions
So far, several factors have limited the success of the green revolutions and may limit them more in the future. For example, without large inputs of water and synthetic inorganic fertilizers and pesticides, most green revolution and genetically engineered crop varieties produce yields that are no higher (and are sometimes lower) than those from traditional strains. Climate change and the growing world population also limit the success of green revolutions. The high inputs required to sustain green revolutions also cost too much for most subsistence farmers in less-developed countries.
Scientists point out that at some point yields stop increasing because of the inability of crop plants to take up nutrients from additional fertilizer and irrigation water. This helps to explain the slowdown in the rate of growth in global yields for most major crops since 1990.
Can we expand the green revolutions by irrigating more cropland? Since 1978, the amount of irrigated land per person has been declining, and it is projected to fall much more by 2050. One reason for this is population growth, which is projected to add 2.2 billion more people between 2018 and 2050. Other factors are limited availability of irrigation water, soil salinization, and the fact that most of the world’s farmers cannot afford to irrigate their crops.
Climate change is expected to reduce yields of crops such as wheat, rice, and corn during this century. Mountain glaciers that provide irrigation for many millions of people in China, India, and South America are melting and this will lessen the area of crops that can be irrigated. During this century, fertile croplands in coastal areas, including many of the major rice-growing floodplains and river deltas in Asia, are likely to be flooded by rising sea levels resulting from climate change. Food production could also drop sharply in some major food-producing areas because of longer and more intense droughts and heat waves, also likely resulting from climate change.
Learning from Nature
Scientists are searching for wild relatives of common food crops such as wheat, rice, and corn to produce new climate-smart varieties that can help reduce the harmful effects of climate change. This includes drought-tolerant varieties and varieties of rice that can grow in flooded areas and in salty water that intrudes because of rising sea levels.
Can we expand or extend green revolutions with the use of genetic engineering? Many scientists and engineers argue that we can, but this is a controversial topic. See Science Focus 12.1.
Science Focus 12.1
Controversy over Genetically Engineered Foods
Bioengineers have talked about developing new GM varieties of crops that are resistant to heat, cold, drought, insect pests, parasites, viral diseases, herbicides, and other environmental threats. They also hope to develop crop plants that can grow faster and survive with little or no irrigation and with less use of fertilizer and pesticides. Accomplishing these goals can reduce hunger and increase food security.
However, critics have raised some concerns about the widespread and growing use of GM crops and foods. One concern is that while many people are consuming GM foods daily, we know too little about their long-term health effects. For example, one type of GMO makes use of bacillus thuringiensis, a natural soil bacterium with a gene, known as Bt, that produces a chemical toxic to some insects. This gene has been inserted into corn plants, which then incorporate the Bt toxin in their leaves, making them resistant to damage by certain insects. This has reduced the use of pesticides by 37%. However, the Global Citizens’ Report on the State of GMOs summarized findings indicating that GM crops with Bt toxins could threaten human health by triggering an inflammatory response leading to diseases such as diabetes and heart disease. Proponents of GMOs dispute this finding.
Another problem is that promised yield increases from the use of GM crops have not materialized. Studies have shown small increases during the first years of such use with generally plateauing or falling yields thereafter.
GM crops could also threaten biodiversity. Some GM crops are designed to enable increased use of herbicides, which could be part of the reason for declining populations of Monarch butterflies (see Chapter 4 Case Study) and other pollinators. Declines in pollinators can cause declines in the plant communities that depend on them and the animals that depend on those plants. The end effect could be a cascade of biodiversity losses.
Critics also point out that if GM crops or seeds released into the environment were to cause some harmful genetic or ecological effects those organisms could not be recalled. In addition, genes in plant pollen from genetically engineered crops have been known to spread to non–genetically engineered species. This could result in hybrids with wild crop varieties, which could reduce the natural genetic biodiversity of the wild strains. This could in turn reduce the gene pool from which new species can evolve or be engineered—a violation of the biodiversity principle of sustainability.
Some GM crops require increased use herbicides, which can put farmers on a costly treadmill because they might have to use larger amounts or more toxic herbicides as weeds become resistant to them. One study by scientists at the University of Minnesota found that farmers who cultivated GM crop varieties earned less money over a 14-year period than those who continued to grow non-GM crops.
Some 64 countries require that food labels identify genetically modified food content. Polls consistently indicate that around 90% of U.S. consumers want to have such information clearly listed on food labels. In 2016, Congress passed a law requiring GMO content labels. However, it allows food manufacturers three choices: a symbol, a label, or a digital bar code enabling buyers to read the labels on their smart phones. Many consumers are opposed to having to use a smartphone to scan a bar code to get this information, arguing that it puts the burden on the consumer to find information that should be readily available to all consumers with or without cell phones.
In 2016, an advisory panel of experts for the U.S. National Academies of Science and Engineering concluded that genetically engineered food does not appear to pose serious risks to human health or the environment based on analysis of more than 1,000 studies, testimonies from 80 witnesses in a series of public meetings, and 700 comments submitted by the public. However, the report noted that GM crops have not increased the ability to feed the world because the crops have not substantially increased crop yields, as proponents promised.
The report also pointed that while GM crops have decreased the use of insecticides, some herbicide-resistant GM crops have led to increased herbicide use and to herbicide-resistant superweeds. This has forced farmers to spend more money increasing their use of herbicides or switching to stronger herbicides.
About 90% of scientists and organizations such as the American Medical Association (AMA), the U.S. National Academy of Sciences, the World Health Organization,(WHO), and the American Association for the Advancement of Science (AAAS) have concluded that GM crops are safe to use and that their advantages outweigh their disadvantages (Figure 12.A). However, almost two-thirds of consumers disagree with this conclusion and call for stricter regulation to ensure the safety of this rapidly growing technology.
Figure 12.A
Use of genetically modified crops and foods has advantages and disadvantages.
Critical Thinking:
Do the advantages outweigh the disadvantages? Why or why not?
An illustration provides information about Genetically Modified Crops and Foods in three columns. The first column comprises of information of potential benefits that reads, “May need less fertilizer, pesticides, and water, can be resistant to insects, disease, frost, and drought, can grow faster and could raise yields, may tolerate higher levels of herbicides, and could have longer shelf life.” The second column shows the photo of tomatoes and the photo of two corns placed in a plate. The third column provides information about possible drawbacks that reads, “have unpredictable genetic and ecological effects, may put toxins in food, could repel or harm pollinators, can promote pesticide-resistant insects, herbicide-resistant weeds, and plant diseases, and could disrupt seed market and reduce biodiversity.” The entire information is encapsulated in a box and the heading reads, “Trade-offs.”
Top: Lenar Musin/ Shutterstock.com. Bottom: Oksana Shufrych/ Shutterstock.com
Can we increase the food supply by cultivating more land? Clearing more tropical forests and irrigating arid land could more than double the area of the world’s cropland. However, massive clearing of forests and irrigation of arid land would decrease biodiversity, speed up climate change and its harmful effects, and increase soil erosion. In addition, much of this land has poor soil fertility, steep slopes, or both, and cultivating such land would be expensive and probably not ecologically sustainable.
Commercial fertilizers have played a role in green revolutions, but their use in more-developed countries has reached a level of diminishing returns in terms of increased crop yields. However, there are parts of the world, especially in Africa, where additional fertilizer could boost crop production.
12.3j
Environmental Impact of Industrialized Meat Production
Industrialized meat production has increased meat supplies, reduced overgrazing, and kept food prices down. However, feedlots (Figure 12.12) and CAFOs (Figure 12.13) have widespread harmful health and environmental effects. Analysts point out that meat produced by industrialized agriculture is artificially cheap because most of its harmful environmental and health costs are not included in the market prices of meat and meat products, a violation of the full-cost pricing principle of sustainability.
A major problem with feedlots and CAFOs is that huge amounts of water are used to irrigate the grain crops that feed the livestock. According to waterfootprint.org, producing a quarter-pound hamburger requires 1,752 liters (63 gallons) of water. This is four to six times what the average American uses every day for all household water needs, the largest of which is flushing toilets.
Large volumes of water are also used to wash away livestock wastes. Much of this wastewater flows into streams and other waterways and pollutes those aquatic ecosystems.
Another problem is what to do with the wastes (mostly manure) produced by feedlots and CAFOs. According to the USDA, animal waste produced by the American meat industry amounts to about 67 times the amount of waste produced by the country’s human population. Ideally, manure from CAFOs should be returned to the soil as a nutrient-rich fertilizer in keeping with the chemical cycling principle of sustainability. However, it is often so contaminated with residues of antibiotics and pesticides that it is unfit for use as a fertilizer.
Despite potential contamination, up to half of the manure slurry from CAFOs in the United States is applied to crop fields and creates severe odor problems for people living nearby. Much of the other half of CAFO animal waste is pumped into large lagoons, which can leak and pollute nearby surface and groundwater, overflow when exposed to excessive rain, produce foul odors, and emit large quantities of climate-changing greenhouse gases into the atmosphere.
Industrialized meat production uses large amounts of energy (mostly from oil), which make it a major source of air and water pollution and greenhouse gas emissions. For example, producing a pound of beef emits an amount of climate-changing into the atmosphere that is equivalent to driving an average American car 113 kilometers (70 miles). In addition, as part of their digestion process, cattle and dairy cows release methane , a greenhouse gas with about 25 times the warming potential of per molecule. According to the FAO study, Livestock’s Long Shadow, industrialized livestock production generates about 18% of the world’s greenhouse gases—more than all of the world’s cars, trucks, airplanes, and ships combined.
Beef and lamb have the highest climate-change footprints per gram of protein. In addition, the stomachs of cows and sheep contain bacteria that help them digest grass and other foods. These bacteria produce the potent greenhouse gas methane, which is released in burps and flatulence. Scientists are trying to find ways to reduce methane emissions from cows by introducing seaweed or other additives in their feed. Cheese and farmed shrimp also have high climate-change footprints. According to a number of studies, chicken and other poultry have a lower climate-change impact than other livestock. Plants have the lowest climate-change impacts.
Another growing problem is the use of antibiotics in industrialized livestock production facilities. The U.S. Food and Drug Administration (FDA) and the Union of Concerned Scientists estimate that 70% to 80% of all antibiotics used in the United States (and 50% of those in the world) are added to animal feed. This is done to help prevent the spread of diseases in feedlots and CAFOs and to promote the growth of the animals before they are slaughtered. According to FDA data and several studies, this heavy use of antibiotics plays a role in the rise of genetic resistance among many disease-causing bacteria (see Figure 4.14). Such resistance can reduce the effectiveness of some antibiotics used to treat humans for bacterial infections, and it can promote the development of new, more genetically resistant infectious disease organisms, some of which can infect humans.
Figure 12.23 summarizes key advantages and disadvantages of using animal feedlots and CAFOs.
Figure 12.23
Use of animal feedlots and confined animal feeding operations has advantages and disadvantages.
Critical Thinking:
Do the advantages outweigh the disadvantages? Why or why not?
An illustration shows information about Feedlots and CAFOs in three columns. The first column provides information about the Advantages that reads, “Increased meat production, higher profits, less land use, reduced overgrazing, reduced soil erosion, and protection of biodiversity.” The second column shows the photo of cattle feeding and another photo shows chickens being fed through confined animal feeding operations. The third column provides information about disadvantages that reads, “Animals unnaturally confined and crowded, large inputs of grain, fishmeal, water, and fossil fuels, greenhouse gases such carbon-di-oxide and methane emissions, concentration of animal wastes that can pollute water, and use of antibiotics can increase genetic resistance to microbes in humans.” The entire information is encapsulated in a box and the heading reads, “Trade-offs.”
Top: Mikhail Malyshev/ Shutterstock.com. Bottom: Maria Dryfhout/ Shutterstock.com.
When livestock are grass-fed, environmental impacts can still be high, especially when forests are cut down or burned to make way for grazing land, as is done in Brazil’s Amazon forests. According to an FAO report, overgrazing and erosion by livestock has degraded about 20% of the world’s grasslands and pastures. The same report estimated that rangeland grazing and industrialized livestock production has caused about 55% of all topsoil erosion and sediment pollution.
In addition, grass-fed cows emit more of the powerful greenhouse gas methane than do grain-fed cows. Thus, expanding grass-fed production could increase the agricultural contributions to deforestation and climate change.
Connections
Meat Production and Aquatic Biodiversity
Synthetic fertilizers are used in the Midwestern United States to produce corn for animal feed and ethanol fuel for cars. Much of this fertilizer washes from cropland and into the Mississippi River, which empties into the Gulf of Mexico. The added nitrate and phosphate nutrients overfertilize the gulf’s coastal waters. Each year this leads to oxygen depletion in the gulf’s waters, which threatens one-fifth of the nation’s seafood yield. In other words, growing corn in the Midwest, largely to feed cattle and fuel cars, degrades aquatic biodiversity and seafood production in the Gulf of Mexico.
12.3k
Environmental Impact of Aquaculture
Aquaculture produces about 47% of the world’s seafood, according to the FAO, and is growing rapidly. In 2017, China accounted for 60% of the world’s aquaculture production. The World Bank projects that by 2030, aquaculture could produce 62% of all seafood. Figure 12.24 lists key advantages and disadvantages of aquaculture. Some analysts warn that the harmful environmental effects of aquaculture could limit its future production potential unless efforts are made to make it more sustainable.
Figure 12.24
Aquaculture has advantages and disadvantages.
Critical Thinking:
Do the advantages outweigh the disadvantages? Why or why not?
An illustration provides information about Aquaculture in three columns. The first column provides information about the Advantages and the text below reads, “High efficiency, high yield, reduces overharvesting of fisheries, and jobs and profits.” The second column shows aquaculture farms and a photo of two dead fishes caught while fishing. The third column provides information about the disadvantages and reads, “large inputs of land, grain, and fishmeal, large waste output, loss of mangrove forests and estuaries, and dense population vulnerable to disease.” The entire information is encapsulated in a box and the heading reads, “Trade-offs.”
Top: Vladislav Gajic/ Shutterstock.com. Bottom: FeellFree/ Shutterstock.com.
In the 1990s, up to a third of the wild fish caught from the oceans was used to make the fishmeal and fish oil that were fed to farmed fish. This has contributed to the depletion of many populations of wild fish that are crucial to marine food webs—a serious threat to marine biodiversity and ecosystem services.
In 2016, aquaculture used 69% of all fishmeal and 75% of all fish oil. Some of the fishmeal and fish oil fed to farm-raised fish is contaminated with long-lived toxins such as PCBs and dioxins that are picked up from the ocean floor. This can contaminate farm-raised fish and people who eat such fish. Fish farms, especially those that that raise carnivorous fish such as salmon and tuna also produce large amounts of wastes that can contain pesticides and antibiotics used on fish farms. These chemicals can contaminate farm-raised fish and people who consume such fish. Aquaculture producers contend that the concentrations of these chemicals are not high enough to threaten human health, but some health scientists disagree.
Another problem is that farmed fish can escape their pens and mix with wild fish and possibly disrupt the gene pools of wild populations or become invasive species. Aquaculture can also destroy or degrade aquatic ecosystems, particularly mangrove forests (Figure 8.8) that are cleared for coastal fish farms. This loss of mangrove forests decreases biodiversity and valuable ecosystem services such as natural flood control in these sensitive coastal areas that are expected to experience severe flooding because of rises in sea level caused by climate change.
According to recent research, farmed mollusks (mussels, scallops, and oysters) have low climate-change footprints. On average, farmed salmon have a lower climate change footprint than pork or chicken. However, wild lobster and shrimp can have a larger climate change footprint than pork or chicken because of the fuel burned in fishing boats. On the other hand, wild fish such as sardines, anchovies, tuna, herring, cod, haddock, and pollack on average have lower climate-change footprints than pork or chicken. 12.4a
Nature Helps Control Many Pests
A pest is any species that interferes with human welfare by competing with us for food, invading our homes, lawns, or gardens, destroying building materials, spreading disease, invading ecosystems, or simply being a nuisance. Worldwide, only about 100 species of plants (weeds), animals (mostly insects), fungi, and microbes cause most of the damage to the crops we grow. However, insects consume up to 20% of the plants that we grow for food. That percentage will increase as global warming expands the populations of some insects and makes many insects hungrier by speeding up their metabolism and causing them to reproduce faster. This will decrease crop yields according to a 2018 article by Curtis Deutsch and his scientific colleagues at the University of Washington.
In natural ecosystems and in many polyculture crop fields, natural enemies (predators, parasites, and disease organisms) control the populations of most potential pest species. This free ecosystem service is an important part of the earth’s natural capital. For example, biologists estimate that the world’s 46,700 known species of spiders kill far more crop-eating insects every year than humans do by using insecticides. Most spiders, including the wolf spider (Figure 12.25), do not harm humans.
Figure 12.25
Natural capital: This ferocious-looking wolf spider is eating a grasshopper. It is not harmful to humans.
A photo shows a ferocious looking wolf spider which is eating a grasshopper.
Cathy Keifer/ Shutterstock.com
When we clear forests and grasslands, plant monoculture crops, and douse fields with chemicals that kill pests, we upset many of these natural population checks and balances that are in keeping with the biodiversity principle of sustainability. Then we must devise and pay for ways to protect our monoculture crops, tree plantations, lawns, and golf courses from pests that nature has helped to control at no charge. 12.4bSynthetic Pesticides
Scientists and engineers have developed a variety of synthetic pesticides—chemicals used to kill or control pest organisms. Common types of synthetic pesticides include insecticides (insect killers), herbicides (weed killers), fungicides (fungus killers), and rodenticides (rat and mouse killers).
We did not invent the use of chemicals to repel or kill other species. For nearly 225 million years, plants have been producing chemicals to ward off, deceive, or poison the insects and herbivores that feed on them. Scientists have used such chemicals to create biopesticides to kill some pests.
Learning from Nature
In the 1600s, farmers used nicotine sulfate, extracted from tobacco leaves, as an insecticide. Eventually, other first-generation pesticides—mainly natural chemicals taken from plants—were developed. Farmers were copying nature’s solutions to deal with their pest problems.
A major pest control revolution began in 1939, when entomologist Paul Müller discovered DDT (dichlorodiphenyl-trichloroethane)—the first of the so-called second-generation pesticides produced in the laboratory. It soon became the world’s most-used pesticide, and since then, chemists have created hundreds of other synthetic pesticides.
Some second-generation pesticides have turned out to be hazardous for birds and other forms of wildlife. In 1962 biologist Rachel Carson (
Figure 1.16
) published her famous book Silent Spring, sounding a warning that eventually led to strict controls on the use of DDT and several other widely used pesticides.
Since 1950, synthetic pesticide use has increased more than 50-fold and most of today’s pesticides are 10 to 100 times more toxic to pests than those used in the 1950s. Some synthetic pesticides, called broad-spectrum agents, can be toxic to beneficial species as well as to pests. Examples are organochlorine compounds (such as DDT), organophosphates (such as malathion and parathion), carbamates, pyrethroids, and neonicotinoids (which have been linked to the serious decline in honeybee populations, see
Science Focus 9.2
). Other synthetic pesticides, called selective, or narrow-spectrum agents, are each effective against a narrowly defined group of organisms. One example is glyphosate, a widely used herbicide that kills weeds without hurting crops. It is used on corn and soybean crops that are genetically modified to withstand its toxic effects.
50-Fold
The increase in synthetic pesticide use since 1950
Pesticides vary in their persistence, the length of time they remain deadly in the environment. Some, such as DDT and related compounds, remain in the environment for years and can be biologically magnified in food chains and food webs (Figure 9.14). Others, such as organophosphates, are active for days or weeks and are not biologically magnified but can be highly toxic to humans.
About one-fourth of the pesticides used in the United States are aimed at ridding houses, gardens, lawns, parks, and golf courses of insects and other pests. According to the U.S. Environmental Protection Agency (EPA), the amount of synthetic pesticides used on the average U.S. homeowner’s lawn is 10 times the amount (per unit of land area) typically used on U.S. croplands.
Most pesticides are used to protect crops. However, some are used for other purposes. This includes poisoning livestock predators, killing animals for their parts including ivory and fur, and killing animals for their meat.
12.4cBenefits of Synthetic Pesticides
The use of synthetic pesticides has advantages and disadvantages. Proponents contend that the benefits of pesticides (
Figure 12.26
, left) outweigh their harmful effects (Figure 12.26, right). They point to the following benefits:
·
They have saved human lives. Since 1945, DDT and other insecticides probably have prevented the premature deaths of at least 7 million people (some say as many as 500 million people) from insect-transmitted diseases such as malaria (carried by the Anopheles mosquito), bubonic plague (carried by rat fleas), and typhus (carried by body lice and fleas).
· They can increase food supplies by reducing food losses due to pests, for some crops.
· They can help farmers control soil erosion and build soil fertility. In conventional no-till farming (
Core Case Study), farmers apply herbicides instead of weeding the soil by plowing. This dramatically reduces soil erosion and soil nutrient depletion.
· They can help farmers to reduce costs and increase profits. The costs of using pesticides can be regained, at least in the near term, through higher crop yields.
· They work fast. Pesticides control most pests quickly, have a long shelf life, and are easily shipped and applied.
· Newer pesticides are safer to use and more effective than many older ones. Greater use is being made of biopesticides derived from plants, which are generally safer to use and less damaging to the environment than are many older pesticides.
Figure 12.26
Use of synthetic pesticides has advantages and disadvantages.
Critical Thinking:
1. Do the advantages outweigh the disadvantages? Why or why not?
B Brown/ Shutterstock.com
12.4d
Problems with Synthetic Pesticides
Opponents of widespread use of synthetic pesticides contend that the harmful effects of these chemicals (Figure 12.26, right) outweigh their benefits (Figure 12.26, left). They cite several problems.
They accelerate the development of genetic resistance to pesticides in pest organisms (Figure 12.27). Insects breed rapidly, and within 5 to 10 years (much sooner in tropical areas), they can develop immunity to widely used pesticides through natural selection. In the same way, weeds develop genetic resistance to herbicides. Since 1945, about 1,000 species of insects and rodents (mostly rats) have developed genetic resistance to one or more pesticides.
They can put farmers on a financial treadmill. Farmers typically find themselves having to pay more and more for a chemical pest control program that can become less and less effective as pests develop genetic resistance to the pesticides.
Some insecticides kill natural predators and parasites that help to control the pest populations. About 100 of the 300 most destructive insect pests in the United States were minor pests until widespread use of insecticides wiped out many of their natural predators. (See the Case Study that follows.)
Some pesticides harm wildlife. According to the USDA and the U.S. Fish and Wildlife Service, each year, some of the pesticides applied to crops poison honeybee colonies on which we depend for pollination of many food crops (see Chapter 9 Core Case Study and Science Focus 9.2). According to a study by the Center for Biological Diversity, pesticides menace about a third of all endangered and threatened species in the United States.
Pesticides are usually applied inefficiently and can pollute the environment. According to the USDA, about 98–99.9% of the insecticides and more than 95% of the herbicides applied by aerial spraying or ground spraying do not reach the target pests. They end up in the air, surface water, groundwater, bottom sediments, food, and nontarget organisms, including humans.
Some pesticides threaten human health. The WHO and UNEP have estimated that pesticides annually poison at least 3 million agricultural workers worldwide. According to a 2017 UN report, pesticides cause about 200,000 deaths per year worldwide. Household pesticides such as ant and roach sprays sicken another 2.5 million people per year. According to studies by the National Academy of Sciences, pesticide residues in food cause an estimated 4,000–20,000 cases of cancer per year in the United States. The pesticide industry disputes these claims, arguing that if used as directed, pesticides do not remain in the environment at levels high enough to cause serious environmental or health problems.
Figure 12.27
When a pesticide is sprayed on a crop (a), a few pest insects resist it and survive (b). The survivors reproduce and pass on their trait for resistance to the pesticide (c). When the crop is sprayed again (d), more insects resist and survive it and continue reproducing (e). The pesticide has now become ineffective and the farmer must look for a stronger pesticide.
An illustration shows five photos of a corn namely a, b, c, d, and e. The photo a shows pesticide being sprayed on a corn and a few pest insects that survive are shown over the corn. The photo b shows a few pest insects lying dead on the floor and one of the pest insect is shown moving live over the corn. The photo c shows many pest insects spread over the corn. The photo d shows pesticide being sprayed again over the pest insects spread over the corn. The photo e shows only a few pest insects lying dead on the floor and the others spread over the corn.Enlarge Image
Figure 12.28 lists some ways to reduce your exposure to synthetic pesticides.
Figure 12.28
Individuals matter: You can reduce your exposure to pesticides.
Critical Thinking:
Which three of these steps do you think are the most important ones to take? Why?
An illustration provides information about Reducing Exposure to Pesticides in bulleted points that read the text, “Grow some of your food using organic methods, buy certified organic food, wash and scrub all fresh fruits and vegetables, eat less meat, no meat, or certified organically produced meat, and before cooking trim the fat from meat.”
Connections
Pesticides and Food Choices
The Environmental Working Group (EWG) produces an annual list of fruits and vegetables that tend to have the highest and lowest pesticide residues. In 2019, these foods with the highest pesticide residues (EWG’s “dirty dozen”) were strawberries, spinach, kale, nectarines, apples, grapes, peaches, cherries, pears, tomatoes, celery, and potatoes unless they were USDA certified organically grown. In 2019, the “clean 15” with the lowest pesticide residues were avocadoes, sweet corn, pineapples, sweet peas, onions, papayas, eggplants, asparagus, kiwi, cabbage, cauliflower, cantaloupes, broccoli, mushrooms, and honeydew melons.
Case Study
Ecological Surprises: Unintended Consequences
Malaria once infected 9 of every 10 people in North Borneo, now known as the eastern Malaysian state of Sabah. In 1955, the WHO sprayed the island with dieldrin (a DDT relative) to kill malaria-carrying mosquitoes. The program was so successful that the dreaded disease was nearly eliminated.
Then unexpected things began to happen. The dieldrin also killed other insects, including flies and cockroaches living in houses, which made the islanders happy. Next, small insect-eating lizards living in the houses died after gorging themselves on dieldrin-contaminated insects. Then cats began dying after feeding on the lizards. In the absence of cats, rats flourished in and around the villages. When the residents became threatened by sylvatic plague carried by rat fleas, the WHO parachuted healthy cats onto the island to help control the rats. Operation Cat Drop worked.
Then the villagers’ roofs began to fall in. The dieldrin had killed wasps and other insects that fed on a type of caterpillar that was not affected by the insecticide. With most of its predators eliminated, the caterpillar population exploded, munching its way through its favorite food: the leaves used in thatch roofs.
Ultimately, this story ended well. Both malaria and the unexpected effects of the spraying program were brought under control. Nevertheless, this chain of unintended and unforeseen consequences reminds us that whenever we intervene in nature and affect organisms that interact with one another, we need to ask, “Now what will happen?”
12.4eEffectiveness of Synthetic Pesticides in the United States
Largely because of genetic resistance and the loss of many natural predators, synthetic pesticides have not always succeeded in reducing U.S. crop losses. David Pimentel, an expert on insect ecology, evaluated data from more than 300 agricultural scientists and economists. He found that between 1942 and 1997, estimated crop losses from insects in the United States almost doubled from 7% to 13%, despite a 10-fold increase in the use of synthetic insecticides. He also estimated that alternative pest management practices could cut the use of synthetic pesticides by half on 40 major U.S. crops without reducing crop yields.
The pesticide industry disputes such findings. However, numerous studies and experience support them. For example, Sweden has cut its pesticide use in half with almost no decrease in crop yields.
12.4fRegulating Synthetic Pesticide Use
In the United States, three federal agencies, the EPA, the USDA, and the FDA, regulate the use of these pesticides under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), first passed in 1947 and amended in 1972. Critics argue that that FIFRA has not been well enforced, and the EPA says that the U.S. Congress has not provided them with enough funds to carry out the complex and lengthy process of evaluating pesticides for toxicity.
In 1996, Congress passed the Food Quality Protection Act, mostly because of growing scientific evidence and citizen pressure concerning the effects of small amounts of pesticides on children. This act requires the EPA to reduce the allowed levels of pesticide residues in food by a factor of 10 when there is inadequate information on the potentially harmful effects on children. Some scientists call for reducing the levels for children by a factor of 100.
Between 1972 and 2018, the EPA used FIFRA to ban or severely restrict the use of 64 active pesticide ingredients, including DDT and most other chlorinated hydrocarbon insecticides. However, according to studies by the National Academy of Sciences, federal laws regulating pesticide use generally are inadequate and poorly enforced. A 2015 study by the U.S. General Accounting Office found that the FDA tests less than one-tenth of 1% of all imported fruits and vegetables. The FDA also does not test foods for some pesticide residues that are strictly regulated by the EPA.
Although laws within countries protect citizens to some extent, banned or unregistered pesticides may be manufactured in one country and exported to other countries. For example, U.S. pesticide companies make and export to other countries pesticides that have been banned or severely restricted—or never evaluated—in the United States. Other industrial countries also export banned or unapproved pesticides.
In what environmental scientists call a circle of poison, or the boomerang effect, residues of synthetic pesticides that have been banned in one country but exported to other countries can return to the exporting countries on imported food. Winds can also carry persistent pesticides from one country to another.
In 2000, more than 100 countries developed an international agreement to ban or phase out the use of 12 especially hazardous persistent organic pollutants (POPs)—9 of them persistent hydrocarbon pesticides such as DDT and other chemically similar pesticides. By 2018, the initial list of 12 chemicals had been expanded to 28. In 2004, the POPs treaty went into effect—a legal application of the precautionary principle (see
Chapter 9
). By 2018, it had been signed or ratified by 182 countries, not including the United States.
12.4gAlternatives to Synthetic Pesticides
Many scientists urge us to greatly increase the use of biological, ecological, and other alternatives methods for controlling pests and diseases that affect crops and human health. Here are some alternatives:
· Fool the pest. A variety of cultivation practices can be used to fake out pests. Examples include rotating the types of crops planted in a field each year and adjusting planting times so that major insect pests either starve or are eaten by their natural predators.
· Provide homes for pest enemies. Farmers can increase the use of polyculture, which uses plant diversity to reduce losses to pests by providing habitats for the predators of pest species.
· Implant genetic resistance. Use genetic engineering to speed up the development of pest- and disease-resistant crop strains.
· Bring in natural enemies. Use biological control by importing natural predators (
Figures 12.25
and
12.29
), parasites, and disease-causing bacteria and viruses to help regulate pest populations. This approach is nontoxic to other species and is usually less costly than applying pesticides. However, some biological control agents are difficult to mass-produce and are often slower acting and more difficult to apply than synthetic pesticides are. Sometimes the agents can multiply and become pests themselves.
· Use insect scents. Trace amounts of sex attractants (called pheromones) can be used to lure pests into traps or to attract their natural predators into crop fields. Each of these chemicals attracts only one species. They have little chance of causing genetic resistance and are not harmful to nontarget species. However, they are costly and time-consuming to produce.
· Use insect hormones. Hormones produced by animals control their developmental processes at different stages of life. Scientists have learned how to identify and use hormones that disrupt an insect’s normal life cycle, thereby preventing it from reaching maturity and reproducing. Use of insect hormones has some of the same advantages and disadvantages as use of sex attractants has. In addition, they take weeks to kill an insect, are often ineffective with large infestations of insects, and sometimes break down before they can act.
· Use natural methods to control weeds. Farmers can control weeds by methods such as crop rotation, mechanical cultivation, hand weeding, and the use of cover crops and mulches.
Figure 12.29
Natural Capital: In this example of biological pest control, a wasp is parasitizing a gypsy moth caterpillar.
Scott Bauer/USDA Agricultural Research Service
12.4hIntegrated Pest Management
Many pest control experts and farmers believe the best way to control crop pests is through
integrated pest management (IPM)
, a program in which each crop and its pests are evaluated as parts of an ecosystem. The overall aim of IPM is to reduce crop damage to an economically tolerable level with minimal use of synthetic pesticides.
When farmers using IPM detect an economically damaging level of pests in a field, they start with biological methods (natural predators, parasites, and disease organisms) and cultivation controls (such as altering planting times and growing different crops on fields from year to year to disrupt pests). They apply small amounts of synthetic pesticides only when insect or weed populations reach a threshold where the potential cost of pest damage to crops outweighs the cost of applying the pesticide.
IPM works. In Sweden and Denmark, farmers have used it to cut their synthetic pesticide use by more than half. In Cuba, where organic farming is used almost exclusively, farmers make extensive use of IPM. In Brazil, IPM has reduced pesticide use on soybeans by as much as 90%. In Japan, many farmers save money by using ducks for pest control in rice paddies. The ducks’ droppings also provide nutrients for the rice plants.
According to the U.S. National Academy of Sciences, a well-designed IPM program can reduce synthetic pesticide use and pest control costs by 50–65%, without reducing crop yields and food quality. IPM can also reduce inputs of fertilizer and irrigation water and slow the development of genetic resistance because of reduced use of pesticides. IPM is an important example of pollution prevention that reduces risks to wildlife and human health and applies the biodiversity principle of sustainability.
Despite its important benefits, IPM has some drawbacks. It requires expert knowledge about each pest situation and takes more time than does relying solely on synthetic pesticides. Methods developed for a crop in one area might not apply to areas with even slightly different growing conditions. Initial costs may be higher, although long-term costs typically are lower than the use of conventional pesticides. Widespread use of IPM has been hindered in the United States and other countries by government subsidies that support use of synthetic pesticides, as well as by opposition from pesticide manufacturers, and a shortage of IPM experts. GREEN CAREER: Integrated pest management
A growing number of scientists urge the USDA to use a three-point strategy to promote IPM in the United States. First, add a small sales tax on synthetic pesticides and use the revenue to fund IPM research and education. Second, set up a federally supported IPM demonstration project on at least one farm in every county in the United States. Third, train USDA field personnel and county farm agents in IPM so they can help farmers use this alternative.
Several UN agencies and the World Bank have joined to establish an IPM facility. Its goal is to promote the use of IPM by disseminating information and establishing networks among researchers, farmers, and agricultural extension agents involved in IPM.
12.6bGovernment and Private Programs
Government and private programs aimed at reducing poverty can improve food security. For example, some programs provide small loans at low interest rates to poor people to help them start businesses or buy land to grow their own food.
Some analysts urge governments to establish special programs focused on saving children from the harmful health effects of poverty. Studies by the United Nations Children’s Fund (UNICEF) indicate that one-half to two-thirds of nutrition-related childhood deaths could be prevented at an average annual cost of $5 to $10 per child. This involves simple measures such as immunizing more children against childhood diseases, preventing dehydration due to diarrhea by giving infants a mixture of sugar and salt in their water, and combatting blindness by giving children an inexpensive vitamin A capsule twice a year.
Some farmers and plant breeders are working on preserving a diverse gene pool as another way to improve food security. For example, an organization called the Global Crop Diversity Trust is seeking to prevent the disappearance of 100,000 varieties of food crops. The trust is working with about 50 seed banks around the world to cultivate and store seeds from endangered varieties of many food plant species.
In the quest for food security, some critics recognize the potential benefits of genetically modified (GM) crops (
Figure 12.A
, left). However, they point out that most of the GM crops developed so far have provided very few of these benefits and have potentially serious drawbacks (
Figure 12.A
, right).
Still, many scientists think that GM crops hold great promise. A survey by the Pew Research Center and the American Association for the Advancement of Science (AAAS) indicated that 88% of AAAS scientists polled think it is safe to eat GM foods, while only 37% of the public agreed with this.
Individuals and many private, mostly nonprofit, organizations are working to help individuals, communities, and nations to improve their food security and produce food more sustainably. For example, between 1993 and 2017, long-time farmer Will Allen operated an ecologically-based farm in the city of Milwaukee, Wisconsin. Called Growing Power, it became a model for more sustainable agriculture. Allen showed how 150 varieties of organic crops could be grown sustainability in greenhouses at an affordable price, along with organically raised chickens, turkeys, goats, fish, and honeybees. It was powered partially by solar electricity and solar hot water systems. Wastes from farmed fish were recycled as nutrients for some of the crops. Every year, Growing Power also helped about 1,000 people learn organic farming methods.
Sustainable agriculturalists and National Geographic Explorers Cid Simones and Paola Segura work with small farmers to show them how to grow food more sustainably on small plots in the tropical forests of Brazil. They train one family at a time. In return, each family must teach five other families and thus help to spread more sustainable farming methods.
12.6cGrowing and Buying More Food Locally and Cutting Food Waste
One way to increase food security is to grow more of our food locally or regionally, ideally with USDA 100% certified organic farming practices. A growing number of consumers are becoming locavores, who try to buy as much of their food as possible from local and regional producers in farmers’ markets, which provide access to fresher seasonal foods, many of them grown organically.
In addition, many people participate in community-supported agriculture (CSA) programs. In these programs, people buy shares of a local farmer’s crops and receive a box of fruits or vegetables on a regular basis during the growing season. For many of these people, the organically grown food they get from the urban farm greatly improves their diets and increases their chances of living longer and healthier lives.
By buying locally, people support local economies and farm families. Buying locally also reduces fossil fuel energy costs for food producers, as well as the greenhouse gas emissions from storing and transporting food products over long distances. There are limits to this benefit, however. Food scientists point out that the largest share of carbon footprint for most foods is in production. Thus, for example, an apple grown through high-input agriculture and trucked across North America could have a larger footprint than an apple grown through low-input farming and sent on a ship from South America.
An increase in the demand for locally grown food could result in more small, diversified farms that produce organic, minimally processed food from plants and animals. Such eco-farming could be one of this century’s new careers for many young people. GREEN CAREER: Small-scale sustainable agriculture
Sustainable agriculture entrepreneurs and ordinary citizens who live in urban areas could grow more of their own food. According to the USDA, approximately 15% of the world’s food is grown in urban areas, and this percentage could easily be doubled. Increasingly, people are sharing garden space, labor, and produce in community gardens (
Figure 12.37
) in vacant lots. People are planting gardens and raising chickens in backyards, growing dwarf fruit trees in large containers of soil, and raising vegetables in containers on rooftops, balconies, and patios. One study estimates that converting 10% of American lawns into food-producing gardens would supply one-third of the country’s fresh produce.
Figure 12.37
Community gardens like this one are helping people without much land to grow their own food.
Alison Hancock/ Shutterstock.com
Many urban schools, colleges, and universities are benefitting from having gardens on school grounds. Not only do the students have a ready source of fresh produce, but they also learn about where their food comes from and how to grow food more sustainably.
Finally, we can sharply cut food waste. According to the FAO, about one-third of the food produced for human consumption is lost or wasted. This is enough food to feed all of the world’s 815 million hungry people. It is equivalent to the output of an area of cropland almost half as large as the continental United States.
33%
Percentage of the world’s food that is lost or wasted
In poor countries with unreliable food storage and transportation, much food is lost before it gets to consumers. In wealthy countries, much waste occurs in restaurants, homes, and supermarkets. According to studies by the EPA and the Natural Resources Defense Council, Americans throw away 30–40% of the country’s food supply each year while 40 million Americans experience chronic hunger. An American family of four typically wastes an average $1,484 of edible food a year. Most food waste ends up in landfills, where it decomposes and emits methane, a potent greenhouse gas.
Big Ideas
· About 815 million people have health problems because they do not get enough to eat and 2.1 billion people face health problems from eating too much.
· Modern industrialized agriculture has a greater harmful impact on the environment than any other human activity.
· More sustainable forms of food production could greatly reduce the harmful environmental and health impacts of industrialized food production systems.
Tying It All Together
No-Till Farming and Sustainability
A photo shows several vegetables such as carrots, tomatoes, cucumbers, bottle-guard, onions, capsicums, cabbages, green vegetables, etc. which are placed in separate trays and displayed in a pattern so-as-to ease shopping.
Baloncici/ Shutterstock.com
This chapter began with a look at the promises and tradeoffs of no-till farming. This method of farming preserves topsoil, the base of the food web for most of the earth’s people. It lessens the ecological footprint of farming by reducing the need for water and fossil fuels and it creates a beneficial environmental impact by adding to soil quality and storing carbon in the soil, thus keeping it out of the atmosphere and reducing climate change. In doing so, it applies the biodiversity and chemical cycling principles of sustainability. It is one of many possible ways to shift to more sustainable food production. Making that transition means relying more on solar and other forms of renewable energy and less on fossil fuels. It also means sustaining chemical cycling by conserving topsoil and returning crop residues and animal wastes to the soil. It involves working to sustain natural, agricultural, and aquatic biodiversity by relying on a greater variety of crop and animal strains and seafood, produced by certified organic methods and sold locally in grocery stores and farmers’ markets. Controlling pest populations through broader use of conventional and perennial polyculture and integrated pest management will also help to sustain biodiversity.
Such efforts will be enhanced if we slow the growth of the human population and sharply reduce our wasteful use of food and other resources. Governments could help these efforts by replacing environmentally harmful agricultural and fishing subsidies and tax breaks with more environmentally beneficial ones. Finally, the transition to more sustainable food production would be accelerated for the benefit of the environment as well as current and future generations if we could find ways to include the harmful environmental and health costs of food production in the market prices of food, in keeping with the economic, political, and ethical principles of sustainability.
Chapter Review
Doing Environmental Science
For 1 week, weigh the food that is purchased in your home and the food that is thrown out. Also, keep track of the types of food you eat, using categories such as fruits, vegetables, meats, dairy, and other more specific categories if you wish. Record and compare these numbers and other data from day to day. Develop a plan for cutting your household food waste in half. Consider making a similar study for your school cafeteria and reporting the results and your recommendations to school ofChapter Review
Ecological Footprint Analysis
The following table gives the world’s fish harvest and population data.
World Fish Harvest
Years
Fish Catch (million metric tons)
Aquaculture (million metric tons)
Total (million metric tons)
World Population (in billions)
Per Capita Fish Consumption (kilograms/person)
1990
84.8
13.1
97.9
5.27
1991
83.7
13.7
97.4
5.36
1992
85.2
15.4
100.6
5.44
1993
86.6
17.8
104.4
5.52
1994
92.1
20.8
112.9
5.60
1995
92.4
24.4
116.8
5.68
1996
93.8
26.6
120.4
5.76
1997
94.3
28.6
122.9
5.84
1998
87.6
30.5
118.1
5.92
1999
93.7
33.4
127.1
6.00
2000
95.5
35.5
131.0
6.07
2001
92.8
37.8
130.6
6.15
2002
93.0
40.0
133.0
6.22
2003
90.2
42.3
132.5
6.31
2004
94.6
45.9
140.5
6.39
2005
94.2
48.5
142.7
6.46
2006
92.0
51.7
143.7
6.54
2007
90.1
52.1
142.2
6.61
2008
89.7
52.5
142.3
6.69
2009
90.0
55.7
145.7
6.82
2010
89.0
59.0
148.0
6.90
2011
93.5
62.7
156.2
7.00
2012
90.2
66.5
156.7
7.05
Compiled by the authors using data from UN Food and Agriculture Organization and Earth Policy Institute.
1. Use the world fish harvest and population data in the table to calculate the per capita fish consumption for 1990–2012 in kilograms per person. (Hints: 1 million metric tons equals 1 billion kilograms; the human population data are expressed in billions; and per capita consumption can be calculated directly by dividing the total amount consumed by a population figure for any year.)
2. Did per capita fish consumption generally increase or decrease between 1990 and 2012?
3.
In what years did per capita fish consumption decrease?
ficials.
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20th Edition
12.1a
Food Security and Food
Insecurity
Food security
is the condition under which people have access to enough
safe and nutritious food for a
healthy and active lifestyle. More than 1
billion people work in agriculture to produce food on about 38% of the
earth’s ice
–
free land. They produce more than enough food to meet the
basic nutritional needs of every person on the earth. Despite this food
s
urplus, one of every nine people in the world
—
about 815 million in all
—
is
not getting enough to eat. These people face
food insecurity
by having to
live with chronic hunger and poor nutrition that threaten their ability to
lead healthy and active lifestyles. About 98% of the people facing food
insecurity live in less developed countries, and 60% of them are women. In
the United States, about 41 million people (13 million of them children
under age 5) faced food insecurity in
2017.
Most agricultural experts agree that the root cause of food insecurity
is
poverty
, which prevents poor people from growing or buying enough
nutritious food to live healthy and active lives. This is not surprising given
that in 2018, nearly 28% (2.1
billion) of the world’s people, struggled
to
live on the equivalent of $3.10 a day and 760 million people struggled to
live on the equivalent of less than $1.90 a day, according to the World Bank
and the Global Basic Income Foundation. Other obstacles to f
ood security
are war, corruption, bad weather (such as prolonged drought, flooding, and
heat waves), climate change, and the harmful environmental effects of
modern industrialized agriculture.
Each day, there are about 249,000 more people at the world’s di
nner tables
and many of them will have little or no food on their plates. By 2050, there
will likely be at least 2.3 billion more people to feed. Most of these
newcomers will be born in the major cities of less
–
developed countries. A
critical question is h
ow will we feed the projected 9.9 billion people in
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20th Edition
12.1aFood Security and Food
Insecurity
Food security is the condition under which people have access to enough
safe and nutritious food for a healthy and active lifestyle. More than 1
billion people work in agriculture to produce food on about 38% of the
earth’s ice-free land. They produce more than enough food to meet the
basic nutritional needs of every person on the earth. Despite this food
surplus, one of every nine people in the world—about 815 million in all—is
not getting enough to eat. These people face food insecurity by having to
live with chronic hunger and poor nutrition that threaten their ability to
lead healthy and active lifestyles. About 98% of the people facing food
insecurity live in less developed countries, and 60% of them are women. In
the United States, about 41 million people (13 million of them children
under age 5) faced food insecurity in 2017.
Most agricultural experts agree that the root cause of food insecurity
is poverty, which prevents poor people from growing or buying enough
nutritious food to live healthy and active lives. This is not surprising given
that in 2018, nearly 28% (2.1 billion) of the world’s people, struggled to
live on the equivalent of $3.10 a day and 760 million people struggled to
live on the equivalent of less than $1.90 a day, according to the World Bank
and the Global Basic Income Foundation. Other obstacles to food security
are war, corruption, bad weather (such as prolonged drought, flooding, and
heat waves), climate change, and the harmful environmental effects of
modern industrialized agriculture.
Each day, there are about 249,000 more people at the world’s dinner tables
and many of them will have little or no food on their plates. By 2050, there
will likely be at least 2.3 billion more people to feed. Most of these
newcomers will be born in the major cities of less-developed countries. A
critical question is how will we feed the projected 9.9 billion people in
G.Tyler Miller, Scott E. Spoolman
Living in the Environment
20th Edition
Chapter Introduction
·
Core
Case Study
The Colorado River
· 13.1
Earth’s Water Resources
· 13.1a
We Are Managing Freshwater Poorly
· 13.1b
Most of the Earth’s Freshwater Is Not Available to Us
· 13.1c
Groundwater and Surface Water
· 13.1d
Water Use Is Increasing
· 13.1e
Freshwater Shortages Will Grow
· 13.2
Sustainability of Groundwater
· 13.2a
Aquifer Depletion
· 13.2b
Harmful Effects of Overpumping Aquifers
· 13.2c
Tapping Deep Aquifers
· 13.3
Increasing Freshwater Supplies
· 13.3a
Large Dams
· 13.3b
Removing Salt from Seawater to Provide Freshwater
· 13.4
Water Transfers
· 13.4a
Water Transfers Have Benefits and Drawbacks
· 13.5
Using Freshwater More Sustainably
· 13.5a
Cutting Water Waste
· 13.5b
Improving Irrigation Efficiency
· 1
3.5c
Conserving Water through Low-Tech Methods
· 13.5d
Cutting Freshwater Waste in Industries and Homes
·
13.5e
Using Less Water to Remove Wastes
· 13.6
Flooding
· 13.6a
Some Areas Get Too Much Water
·
13.6b
Reducing Flood Risks
· Tying It All Together
The Colorado River and Sustainability
·
Chapter Review
·
Critical Thinking
·
Doing Environmental Science
·
Ecological Footprint Analysis
· The Colorado River flows 2,300 kilometers (1,400 miles) through seven states to the Gulf of California (
Figure 13.1
). Most of its water comes from snowmelt in the Rocky Mountains. During the past 100 years, this once free-flowing river has been tamed by a gigantic plumbing system consisting of 14 major dams and reservoirs (see
chapter opening photo
) and canals that carry water to farmers, ranchers, industries, and cities.
· Figure 13.1
· The Colorado River basin: The area drained by this river system is more than one-twelfth of the land area of the lower 48 states. This map shows 6 of the river’s 14 dams. The chapter-opening photo shows the Hoover Dam and the Lake Mead reservoir on the Arizona-Nevada border.
·
·
· This system of dams and reservoirs provides electricity from its hydroelectric plants to roughly 40 million people in seven states—about one of every eight people in the United States. The river’s water is used to produce about 15% of the nation’s crops and 13% of its livestock.
· The system supplies water to some of the nation’s driest and hottest cities such as Las Vegas, Nevada, Phoenix, Arizona, and San Diego and Los Angeles, California. Take away the Colorado River’s dam-and-reservoir system, and these cities would become largely uninhabitable desert areas and California’s Imperial Valley would cease producing half of the country’s fruits and vegetables.
· So much water is withdrawn from the Colorado River to grow crops and support cities in a desert-like climate that since 1960, the river has run dry most years before reaching the Pacific Ocean. Since 1999, the river’s watershed has experienced severe
drought
, a prolonged period in which precipitation is lower than normal and evaporation is higher than normal. As a result, the water level in Lake Mead, the largest reservoir in the United States (see
chapter-opening photo
) has been dropping. Climate change is expected to further reduce the river’s flow throughout the remainder of this century
· This overuse of the Colorado River illustrates the challenges faced by governments and people living in arid and semiarid regions with shared river systems. In such areas, increasing population, economic growth, crop irrigation, and climate change are putting increasing demands on limited or decreasing supplies of surface water.
· To many analysts, emerging shortages of water for drinking and irrigation in several parts of the world represent one of the major environmental challenges of this century. In this chapter, we look at where the enormous amount of freshwater that we use comes from, how we can increase the supply of freshwater, how we can use freshwater more sustainably, and how we can reduce the threat of flooding.
· 13.1aWe Are Managing Freshwater Poorly
·
Water is an amazing chemical with unique properties that help to keep us and other species alive (see
Science Focus 3.1
). You could survive for several weeks without food, but only a few days without
freshwater
, or water that contains very low levels of dissolved salts. Water supports the earth’s life and our economies and there is no substitute for this vital form of natural capital. As water expert Sandra Postel puts it, “Water’s gift is life.”
· It takes huge amounts of water to supply food and most of the other things that we use to meet our daily needs and wants. Water also plays a key role in determining the earth’s climates and in removing and diluting some of the pollutants and wastes that we produce. Over eons, water has also sculpted the planet’s surfaces, creating valleys, canyons, and other land features
· Despite its importance, freshwater is one of our most poorly managed resources. We waste it, pollute it, and do not value it highly enough. As a result, it is available at too low a cost to billions of consumers, and this encourages waste and pollution of this resource, for which we have no substitute
· Access to freshwater is a global health issue. The World Health Organization (WHO) has estimated that each year more than 3.4 million die from waterborne infectious diseases—an average of 9,300 deaths each day because they lack access to safe drinking water.
· Access to freshwater is also an economic issue because water is vital for producing food and energy and for reducing poverty. According to the WHO, just 57% of the world’s people have water piped to their homes. The rest have to find and carry it from distant sources or wells. This daily task usually falls to women (
Figure 13.2
), who spend several hours a day collecting freshwater.
· Figure 13.2
· Each day these women carry water to their village in a dry area of India.
·
·
· SHIVJI JOSHI/National Geographic Image Collection
·
Access to freshwater is also a national and global security issue because of increasing tensions within and between some nations over access to limited freshwater resources they share.
Finally, water is an environmental issue. Excessive withdrawal of freshwater from rivers and aquifers has resulted in falling water tables, dwindling river flows (
Core Case Study
), shrinking lakes, and disappearing wetlands. This, in combination with water pollution in many areas of the world, has degraded water quality. It has also reduced fish populations, hastened the extinction of some aquatic species, and degraded aquatic ecosystem services. 13.1bMost of the Earth’s Freshwater Is Not Available to Us
Only 0.024% of the planet’s enormous water supply is readily available to us as liquid freshwater. This water is found in accessible underground deposits and in lakes, rivers, and streams. The rest of the earth’s water is in the salty oceans (about 96.5% of the earth’s volume of liquid water), in frozen polar ice caps and glaciers (1.7%), and underground in deep aquifers (1.7%).
0.024%
Percentage of the earth’s freshwater available to us
Fortunately, the world’s freshwater supply is continually recycled, purified, and distributed in the earth’s hydrologic cycle (see
Figure 3.19
). However, this vital ecosystem service begins to fail when we overload it with water pollutants or withdraw freshwater from underground and surface water supplies faster than natural processes replenish it.
Research indicates that atmospheric warming is altering the water cycle by evaporating more water into the atmosphere. As a result, wet places will get wetter with more frequent and heavier flooding from more rainfall and dry places will get drier with more intense drought.
We have paid little attention to our effects on the water cycle mostly because we think of the earth’s freshwater as a free and infinite resource. As a result, we have placed little or no economic value on the irreplaceable ecosystem services that water provides, a serious violation of the full-cost pricing principle of sustainability.
On a global basis, there is plenty of freshwater, but it is not distributed evenly. Differences in average annual precipitation and economic resources divide the world’s countries and people into water haves and have-nots. For example, Canada, with only 0.5% of the world’s population, has 20% of its liquid freshwater, while China, with 18% of the world’s people, has only 6.5% of the supply.
· 13.1c
· Groundwater and Surface Water
· Much of the earth’s water is stored underground. Some precipitation soaks into the ground and sinks downward through spaces in soil, gravel, and rock until an impenetrable layer of rock or clay stops it. The freshwater in these underground spaces is called groundwater—a key component of the earth’s natural capital (Figure 13.3).
·
· Figure 13.3
· Natural capital: Much of the water that falls in precipitation seeps into the ground to become groundwater, stored in aquifers.
·
· An illustration shows a three-dimensional surface, where a lake is shown and labeled. Several streams arising from the lakes are shown and labeled. Vegetation is found around the streams. Clouds are shown above the surface and water precipitates and falls from it and it is labeled as, “precipitation.” Evaporation and Transpiration and separately another Evaporation are indicated as arrow marks pointing upwards. Below the vegetation on the ground level is the water table and infiltration is indicated by downward arrow marks from the water table to the unconfined aquifer (a layer of water) which is located below the water table and confined aquifer is a layer of water below the unconfined aquifer. The layer of soil between the unconfined and confined aquifer is the less permeable material such as clay. Below the confined aquifer is the layer which is confining impermeable rock layer. Run-off is also labelled in the vegetation. The drinking water well is dug until the unconfined aquifer layer and the artesian well is dug until the confined aquifer layer.Enlarge Image
· The spaces in soil and rock close to the earth’s surface hold little moisture. However, below a certain depth, in the zone of saturation, these spaces are completely filled with freshwater. The top of this groundwater zone is the water table. The water table rises in wet weather. It falls in dry weather or when we remove groundwater from this zone faster than nature can replenish it.
·
· Deeper down are geological layers called aquifers, caverns and porous layers of sand, gravel or rock through which groundwater flows. Some aquifers contain caverns with rivers of groundwater flowing through them. Most aquifers are like large, elongated sponges through which groundwater seeps—typically moving only a meter or so (about 3 feet) per year and rarely more than 0.3 meter (1 foot) per day. Watertight (impermeable) layers of rock or clay below such aquifers keep the freshwater from escaping deeper into the earth. We use pumps to bring this groundwater to the surface for irrigating crops, supplying households, and meeting the needs of industries.
·
· Most aquifers are replenished, or recharged, naturally by precipitation that sinks downward through exposed soil and rock. Others are recharged from the side from nearby lakes, rivers, and streams.
·
· According to the U.S. Geological Survey (USGS), groundwater makes up 95% of the freshwater available to us and other forms of life. However, most aquifers recharge slowly and in urban areas so much of the landscape has been built on or paved over that freshwater can no longer penetrate the ground to recharge aquifers. In dry areas of the world, there is little precipitation available to recharge aquifers. Aquifers lying beneath the recharge zone are called deep aquifers. They either cannot be recharged or take thousands of years to recharge. On a human timescale, deep aquifers are nonrenewable deposits of freshwater.
·
· Another crucial resource is surface water, the freshwater from rain and melted snow that flows or is stored in lakes, reservoirs, wetlands, streams, and rivers. Precipitation that does not soak into the ground or return to the atmosphere by evaporation is called surface runoff. The land from which surface runoff drains into a particular stream, lake, wetland, or other body of water is called its watershed, or drainage basin. The drainage basin for the Colorado River is shown in yellow and green on the map in Figure 13.1 (Core Case Study).
·
· Connections
· Groundwater and Surface Water
There is usually a connection between surface water and groundwater because much groundwater flows into rivers, lakes, estuaries, and wetlands. Thus, if we remove groundwater in a particular location faster than it is replenished, nearby streams, lakes, and wetlands can dry up. This process degrades aquatic biodiversity and other ecosystem services. 13.1dWater Use Is Increasing
According to hydrologists, scientists who study water and its properties and movement, two-thirds of the annual surface runoff of freshwater into rivers and streams is lost in seasonal floods and is not available for human use. The remaining one-third is
reliable surface runoff
—defined as the portion of runoff that is regarded as a stable source of freshwater from year to year. GREEN CAREER: Hydrologist
Since 1900, the human population tripled, global water withdrawals increased sevenfold, and per capita water withdrawals quadrupled. As a result, we now withdraw an estimated 34% of the world’s reliable runoff. This is a global average. In the arid American southwest, up to 70% of the reliable runoff is withdrawn for human purposes, mostly for irrigation. Some water experts project that because of population growth, rising rates of water use per person, longer dry periods in some areas, and unnecessary water waste, we are likely to be withdrawing up to 90% of the world’s reliable freshwater runoff by 2025.
Worldwide, we use 70% of the freshwater we withdraw each year from rivers, lakes, and aquifers to irrigate cropland and raise livestock. In arid regions, up to 90% of the regional water supply is used for food production. Industry uses roughly another 20% of the water withdrawn globally each year. Cities and residences use the remaining 10%.
Your
water footprint
is a rough measure of the volume of freshwater that you use directly or indirectly. Your daily water footprint includes the freshwater you use directly (for example, to drink, bathe, or flush a toilet) and the water you use indirectly through the food, energy, and products you consume. (See the Case Study that follows for information on U.S. water use.) The three largest water footprints in the world belong to India, the United States, and China, in that order.
Case Study
Freshwater Resources in the United States
According to the U.S. Geological Survey (USGS), the major uses of groundwater and surface freshwater in the United States are the cooling of electric power plants, irrigation, public water supplies, industry, and livestock production (
Figure 13.5
, left). The average American directly uses about 370 liters (98 gallons) of freshwater a day—enough water to fill 2.5 typical bathtubs. (The average bathtub can contain about 151 liters or 40 gallons of water.) Household water is used mostly for flushing toilets, washing clothes, taking showers, and running faucets, or is lost through leaking pipes, faucets, and other fixtures (Figure 13.5, right).
Figure 13.5
Comparison of primary uses of water in the United States (left) and uses of water in a typical U.S. household (right).
Data Analysis:
1. In the right-hand chart, which three categories, added together, are smaller than the amount of water lost in leaks?
(Compiled by the authors using data from U.S. Geological Survey, World Resources Institute, and American Water Works Association.)
The United States has more than enough renewable freshwater to meet its needs. However, it is unevenly distributed and much of it is contaminated by agricultural and industrial practices. The eastern states usually have ample precipitation, whereas many western and southwestern states have little (
Figure 13.6
).
Figure 13.6
Long-term average annual precipitation and major rivers in the continental United States.
(Compiled by the authors using data from U.S. Water Resources Council and U.S. Geological Survey.)
In the eastern United States, most water is used for manufacturing and for cooling power plants (with most of the water heated and returned to its source). In many parts of this area, the most serious water problems are flooding, occasional water shortages because of drought, and pollution.
In the arid and semiarid regions of the western half of the United States (Core Case Study), irrigation counts for as much as 85% of freshwater use. Much of it is lost to evaporation and a great deal of it is used to grow crops that require a lot of water. The major water problem is a shortage of freshwater runoff caused by low precipitation (Figure 13.6), high evaporation, and recurring prolonged drought.
Groundwater is one of the most precious of all U.S. resources. About half of all Americans (and 95% of all rural residents) rely on it for drinking water. It makes up about half of all irrigation water, feeds about 40% of the country’s streams and rivers, and provides about one-third of the water used by U.S. industries.
Water tables in many water-short areas, especially in the dry western states, are dropping as farmers and rapidly growing urban areas draw down many aquifers faster than they can be recharged. The U.S. Department of the Interior has mapped out water scarcity hotspots in 17 western states (
Figure 13.7
). In these areas, there is competition for scarce freshwater to support growing urban areas, irrigation, recreation, and wildlife. This competition for freshwater could trigger intense political and legal conflicts between states and between rural and urban areas within states. In addition, Columbia University climate researchers led by Richard Seager used well-tested climate models to project that the southwestern United States is very likely to have long periods of extreme drought throughout most of the rest of this century.
Figure 13.7
Water scarcity hotspots in 17 western states that, by 2025, could face intense conflicts over scarce water needed for urban growth, irrigation, recreation, and wildlife.
Question:
1. Which, if any, of these areas are found in the Colorado River basin (Core Case Study)?
(Compiled by the authors using data from U.S. Department of the Interior and U.S. Geological Survey.)
The Colorado River system (Figure 13.1) is directly affected by such drought. There are three major problems associated with the use of freshwater from this river (Core Case Study). First, the Colorado River basin includes some of the driest lands in the United States and Mexico. Second, long-standing legal agreements between Mexico and the affected western states allocated more freshwater for human use than the river can supply, even in rare years when there is no drought. These pacts allocated no water for protecting aquatic and terrestrial wildlife. Third, since 1960, because of drought, damming, and heavy withdrawals, the river has rarely flowed all the way to the Gulf of California and this has degraded the river’s aquatic ecosystems and dried up its delta (which we discuss later in this chapter).
Freshwater that is not directly consumed but is used to produce food and other products is called
virtual water
. It makes up a large part of the water footprints of individuals, especially in more-developed countries. Agriculture accounts for the largest share of humanity’s water footprint. Producing and delivering a typical quarter-pound hamburger, for example, takes about 2,400 liters (630 gallons or 16 bathtubs) of freshwater—most of it used to grow grain to feed cattle. Producing a smart phone requires about 910 liters (240 gallons or 6 bathtubs) of freshwater.
Figure 13.4
shows one way to measure the amounts of virtual water used for producing and delivering products. These values can vary depending on how much of the supply chain is included, but they give us a rough estimate of the size of our water footprints.
Figure 13.4
Producing and delivering a single one of each of the products listed here requires the equivalent of nearly one and usually many bathtubs full of freshwater, called virtual water.
(Compiled by the authors using data from UN Food and Agriculture Organization, UNESCO-IHE Institute for Water Education, World Water Council, and Water Footprint Network.); Bathtub: Baloncici/ Shutterstock.com.
Coffee
: Aleksandra Nadeina/ Shutterstock.com.
Bread
: Alexander Kalina/ Shutterstock.com. Hamburger: Joe Belanger/ Shutterstock.com. T-shirt: grmarc/ Shutterstock.com. Jeans: Eyes wide/ Shutterstock.com. Car: L Barnwell/ Shutterstock.com. House: Rafal Olechowski/ Shutterstock.com
Note: .
Because of global trade, the virtual water used to produce and transport products such as coffee and wheat (also called embedded water) is often withdrawn as groundwater or surface water in another part of the world. Thus, water can be imported in the form of products, often from countries that are short of water.
Large exporters of virtual water—mostly in the form of wheat, corn, soybeans, and other foods—are the European Union, the United States, Canada, Brazil, India, and Australia. Indeed, Brazil’s supply of freshwater per person is more than 8 times the U.S. supply per person, 14 times China’s supply, and 29 times India’s supply. Brazil is becoming one of the world’s largest exporters of virtual water. However, prolonged severe droughts in parts of Australia, the United States, and the European Union are stressing the abilities of these countries to meet the growing global demand for their food exports.
· 13.1dWater Use Is Increasing
· According to hydrologists, scientists who study water and its properties and movement, two-thirds of the annual surface runoff of freshwater into rivers and streams is lost in seasonal floods and is not available for human use. The remaining one-third is reliable surface runoff—defined as the portion of runoff that is regarded as a stable source of freshwater from year to year. GREEN CAREER: Hydrologist
· Since 1900, the human population tripled, global water withdrawals increased sevenfold, and per capita water withdrawals quadrupled. As a result, we now withdraw an estimated 34% of the world’s reliable runoff. This is a global average. In the arid American southwest, up to 70% of the reliable runoff is withdrawn for human purposes, mostly for irrigation. Some water experts project that because of population growth, rising rates of water use per person, longer dry periods in some areas, and unnecessary water waste, we are likely to be withdrawing up to 90% of the world’s reliable freshwater runoff by 2025.
· Worldwide, we use 70% of the freshwater we withdraw each year from rivers, lakes, and aquifers to irrigate cropland and raise livestock. In arid regions, up to 90% of the regional water supply is used for food production. Industry uses roughly another 20% of the water withdrawn globally each year. Cities and residences use the remaining 10%.
· Your water footprint is a rough measure of the volume of freshwater that you use directly or indirectly. Your daily water footprint includes the freshwater you use directly (for example, to drink, bathe, or flush a toilet) and the water you use indirectly through the food, energy, and products you consume. (See the Case Study that follows for information on U.S. water use.) The three largest water footprints in the world belong to India, the United States, and China, in that order.
· Case Study
· Freshwater Resources in the United States
· According to the U.S. Geological Survey (USGS), the major uses of groundwater and surface freshwater in the United States are the cooling of electric power plants, irrigation, public water supplies, industry, and livestock production (Figure 13.5, left). The average American directly uses about 370 liters (98 gallons) of freshwater a day—enough water to fill 2.5 typical bathtubs. (The average bathtub can contain about 151 liters or 40 gallons of water.) Household water is used mostly for flushing toilets, washing clothes, taking showers, and running faucets, or is lost through leaking pipes, faucets, and other fixtures (Figure 13.5, right).
· Figure 13.5
· Comparison of primary uses of water in the United States (left) and uses of water in a typical U.S. household (right).
· Data Analysis:
· In the right-hand chart, which three categories, added together, are smaller than the amount of water lost in leaks?
·
· (Compiled by the authors using data from U.S. Geological Survey, World Resources Institute, and American Water Works Association.)
· The United States has more than enough renewable freshwater to meet its needs. However, it is unevenly distributed and much of it is contaminated by agricultural and industrial practices. The eastern states usually have ample precipitation, whereas many western and southwestern states have little (Figure 13.6).
· Figure 13.6
· Long-term average annual precipitation and major rivers in the continental United States.
·
· (Compiled by the authors using data from U.S. Water Resources Council and U.S. Geological Survey.)
· In the eastern United States, most water is used for manufacturing and for cooling power plants (with most of the water heated and returned to its source). In many parts of this area, the most serious water problems are flooding, occasional water shortages because of drought, and pollution.
· In the arid and semiarid regions of the western half of the United States (Core Case Study), irrigation counts for as much as 85% of freshwater use. Much of it is lost to evaporation and a great deal of it is used to grow crops that require a lot of water. The major water problem is a shortage of freshwater runoff caused by low precipitation (Figure 13.6), high evaporation, and recurring prolonged drought.
· Groundwater is one of the most precious of all U.S. resources. About half of all Americans (and 95% of all rural residents) rely on it for drinking water. It makes up about half of all irrigation water, feeds about 40% of the country’s streams and rivers, and provides about one-third of the water used by U.S. industries.
· Water tables in many water-short areas, especially in the dry western states, are dropping as farmers and rapidly growing urban areas draw down many aquifers faster than they can be recharged. The U.S. Department of the Interior has mapped out water scarcity hotspots in 17 western states (Figure 13.7). In these areas, there is competition for scarce freshwater to support growing urban areas, irrigation, recreation, and wildlife. This competition for freshwater could trigger intense political and legal conflicts between states and between rural and urban areas within states. In addition, Columbia University climate researchers led by Richard Seager used well-tested climate models to project that the southwestern United States is very likely to have long periods of extreme drought throughout most of the rest of this century.
· Figure 13.7
· Water scarcity hotspots in 17 western states that, by 2025, could face intense conflicts over scarce water needed for urban growth, irrigation, recreation, and wildlife.
· Question:
· Which, if any, of these areas are found in the Colorado River basin (Core Case Study)?
·
· (Compiled by the authors using data from U.S. Department of the Interior and U.S. Geological Survey.)
· The Colorado River system (Figure 13.1) is directly affected by such drought. There are three major problems associated with the use of freshwater from this river (Core Case Study). First, the Colorado River basin includes some of the driest lands in the United States and Mexico. Second, long-standing legal agreements between Mexico and the affected western states allocated more freshwater for human use than the river can supply, even in rare years when there is no drought. These pacts allocated no water for protecting aquatic and terrestrial wildlife. Third, since 1960, because of drought, damming, and heavy withdrawals, the river has rarely flowed all the way to the Gulf of California and this has degraded the river’s aquatic ecosystems and dried up its delta (which we discuss later in this chapter).
· Freshwater that is not directly consumed but is used to produce food and other products is called virtual water. It makes up a large part of the water footprints of individuals, especially in more-developed countries. Agriculture accounts for the largest share of humanity’s water footprint. Producing and delivering a typical quarter-pound hamburger, for example, takes about 2,400 liters (630 gallons or 16 bathtubs) of freshwater—most of it used to grow grain to feed cattle. Producing a smart phone requires about 910 liters (240 gallons or 6 bathtubs) of freshwater. Figure 13.4 shows one way to measure the amounts of virtual water used for producing and delivering products. These values can vary depending on how much of the supply chain is included, but they give us a rough estimate of the size of our water footprints.
· Figure 13.4
· Producing and delivering a single one of each of the products listed here requires the equivalent of nearly one and usually many bathtubs full of freshwater, called virtual water.
·
·
· (Compiled by the authors using data from UN Food and Agriculture Organization, UNESCO-IHE Institute for Water Education, World Water Council, and Water Footprint Network.); Bathtub: Baloncici/ Shutterstock.com. Coffee: Aleksandra Nadeina/ Shutterstock.com. Bread: Alexander Kalina/ Shutterstock.com. Hamburger: Joe Belanger/ Shutterstock.com. T-shirt: grmarc/ Shutterstock.com. Jeans: Eyes wide/ Shutterstock.com. Car: L Barnwell/ Shutterstock.com. House: Rafal Olechowski/ Shutterstock.com
· Note: .
· Because of global trade, the virtual water used to produce and transport products such as coffee and wheat (also called embedded water) is often withdrawn as groundwater or surface water in another part of the world. Thus, water can be imported in the form of products, often from countries that are short of water.
· Large exporters of virtual water—mostly in the form of wheat, corn, soybeans, and other foods—are the European Union, the United States, Canada, Brazil, India, and Australia. Indeed, Brazil’s supply of freshwater per person is more than 8 times the U.S. supply per person, 14 times China’s supply, and 29 times India’s supply. Brazil is becoming one of the world’s largest exporters of virtual water. However, prolonged severe droughts in parts of Australia, the United States, and the European Union are stressing the abilities of these countries to meet the growing global demand for their food exports.
13.2aAquifer Depletion
Aquifers provide drinking water for nearly half of the world’s people and surface water provides drinking water for the other half. In the United States, aquifers supply almost all drinking water in rural areas (but just 20% in urban areas) and 43% of the country’s irrigation water, according to the U.S. Geological Survey (USGS). Most aquifers are renewable resources unless the groundwater they contain is removed faster than it is replenished from rainfall and snowmelt. This practice is referred to as overpumping (see
Case Study that follows). Relying more on groundwater has advantages and disadvantages (
Figure 13.9
).
Case Study
Overpumping the Ogallala Aquifer
In the United States, groundwater is being withdrawn from aquifers, on average, four times faster than it is replenished, according to the USGS.
Figure 13.11
shows the areas of greatest aquifer depletion in the continental United States. One of the most serious cases of overpumping of groundwater is occurring in the lower half of the Ogallala Aquifer. It is one of the world’s largest aquifers, stretching beneath eight states from southern South Dakota to Texas (blowup section of Figure 13.11).
Figure 13.11
Natural capital degradation: Areas of greatest aquifer depletion from groundwater overdraft in the continental United States. The blowup section (right) shows where water levels in the Ogallala Aquifer have dropped sharply at its southern end beneath parts of Kansas, Oklahoma, Texas, and New Mexico.
Critical Thinking:
1. Should the amount of water that farmers can withdraw from the Ogallala Aquifer be restricted? How would you enforce this? How might this affect U.S. food production?
(Compiled by the authors using data from U.S. Water Resources Council and U.S. Geological Survey.)
The Ogallala Aquifer supplies one-third of all the groundwater used in the United States. This aquifer helped make the Great Plains one of world’s most productive irrigated agricultural regions (
Figure 13.12
). However, the Ogallala is a deposit of liquid natural capital with a slow rate of recharge. Scientists estimate that since 1960, we have withdrawn between a third and half the Ogallala’s water and that if it were to be depleted, it could take 6,000 years to recharge naturally.
Figure 13.12
Satellite photo of crop fields in the U.S. state of Kansas. Center-pivot irrigation uses long, suspended pipes that swing around a central point in each field. Dark green circles are irrigated fields of corn, light green circles are sorghum, and light yellow circles are wheat. Brown areas are fields that have been recently harvested and plowed under. The water used to irrigate these crops is pumped from the Ogallala Aquifer.
NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
The Ogallala took about 6,000 years to fill but since 1940s when large-scale irrigation began, its water table levels have declined dramatically. In parts of the southern half of the Ogallala, groundwater is being pumped out 10–40 times faster than the slow natural recharge rate. This has lowered water tables and raised pumping costs, especially in parts of Texas (blowup map in Figure 13.11). The overpumping of this aquifer, along with urban development, restricted access to Colorado River water (Core Case Study), and population growth, have led to a reduced area of irrigated croplands in Texas, Arizona, Colorado, and California. It has also increased competition for water among farmers, ranchers, and growing urban areas.
Government subsidies—payments or tax breaks designed to increase crop production—have encouraged farmers to grow water-thirsty crops in dry areas, which has accelerated depletion of the Ogallala Aquifer. In particular, corn—a very thirsty crop—has been planted widely on fields watered by the Ogallala. Serious aquifer depletion is also taking place in California’s semiarid Central Valley, the long red area in the California portion of Figure 13.11, which supplies half of the country’s fruits and vegetables.
The aquifer also supports biodiversity. In various places, groundwater from the Ogallala flows out of the ground onto land or onto lake bottoms through exit points called springs. In some cases, springs feed wetlands, which are vital habitats for many species, especially birds. When the water tables fall, many of these aquatic oases of biodiversity dry out.
Figure 13.9
Withdrawing groundwater from aquifers has advantages and disadvantages.
Critical Thinking:
1. Do the advantages outweigh the disadvantages? Why or why not?
Top: Ulrich Mueller/ Shutterstock.com
Every day, the world withdraws enough freshwater from aquifers to fill a convoy of large tanker trucks that could stretch 480,000 kilometers (300,000 miles)—well beyond the distance to the moon. Test wells and satellite data (
Science Focus 13.1
) indicate that water tables are falling in many areas of the world because of overpumping. The world’s three largest grain producers—China, the United States, and India—as well as Mexico, Saudi Arabia, Iran, Iraq, Egypt, Pakistan, Spain, and other countries are overpumping many of their aquifers. Much of the Middle East is facing a growing water and food crisis and increasing tensions among its nations, brought on mostly by falling water tables, rapid population growth, and disagreements over access to shared water supplies from the region’s rivers.
As water tables fall from overpumping, farmers drill deeper wells and buy larger pumps to bring more water to the surface. This process eventually depletes the groundwater in some aquifers or at least removes all the water that can be pumped at an affordable cost.
For decades, Saudi Arabia has pumped freshwater from a nonrenewable, deep, aquifer. This water is used to irrigate crops such as wheat grown on desert land (
Figure 13.10
) and to fill fountains and swimming pools, which lose a great deal of water through evaporation into the dry desert air. In 2008, Saudi Arabia announced that irrigated wheat production had largely depleted this major deep aquifer. In 2016, the country stopped producing wheat and imported grain (virtual water) to help feed its 33 million people.
Figure 13.10
Natural capital degradation: Satellite photos of farmland irrigated by groundwater pumped from a deep aquifer in a vast desert region of Saudi Arabia between 1986 (left) and 2004 (right). Irrigated areas appear as green dots (each representing a circular spray system). Brown dots show areas where wells have gone dry, and the land has returned to desert. Since 2004, many more wells have gone dry.
Left: U.N. Environment Programme and U.S. Geological Survey. Right: U.N. Environment Programme and U.S. Geological Survey.
Connections
Aquifer Depletion in California and Meat Consumption in China
Serious aquifer depletion is also taking place in California’s Central Valley where farmers grow alfalfa as a supplemental feed for cattle and dairy cows. Alfalfa requires more water than any other crop in California. Because alfalfa growers make more money by shipping most of their crop to China, they export billions of gallons of virtual water from this drought-ridden area of California to China to support its growing consumption of meat and milk.
· 13.2aAquifer Depletion
· Aquifers provide drinking water for nearly half of the world’s people and surface water provides drinking water for the other half. In the United States, aquifers supply almost all drinking water in rural areas (but just 20% in urban areas) and 43% of the country’s irrigation water, according to the U.S. Geological Survey (USGS). Most aquifers are renewable resources unless the groundwater they contain is removed faster than it is replenished from rainfall and snowmelt. This practice is referred to as overpumping (see Case Study that follows). Relying more on groundwater has advantages and disadvantages (Figure 13.9).
· Case Study
· Overpumping the Ogallala Aquifer
· In the United States, groundwater is being withdrawn from aquifers, on average, four times faster than it is replenished, according to the USGS. Figure 13.11 shows the areas of greatest aquifer depletion in the continental United States. One of the most serious cases of overpumping of groundwater is occurring in the lower half of the Ogallala Aquifer. It is one of the world’s largest aquifers, stretching beneath eight states from southern South Dakota to Texas (blowup section of Figure 13.11).
· Figure 13.11
· Natural capital degradation: Areas of greatest aquifer depletion from groundwater overdraft in the continental United States. The blowup section (right) shows where water levels in the Ogallala Aquifer have dropped sharply at its southern end beneath parts of Kansas, Oklahoma, Texas, and New Mexico.
· Critical Thinking
:
· Should the amount of water that farmers can withdraw from the Ogallala Aquifer be restricted? How would you enforce this? How might this affect U.S. food production?
·
·
· (Compiled by the authors using data from U.S. Water Resources Council and U.S. Geological Survey.)
· The Ogallala Aquifer supplies one-third of all the groundwater used in the United States. This aquifer helped make the Great Plains one of world’s most productive irrigated agricultural regions (Figure 13.12). However, the Ogallala is a deposit of liquid natural capital with a slow rate of recharge. Scientists estimate that since 1960, we have withdrawn between a third and half the Ogallala’s water and that if it were to be depleted, it could take 6,000 years to recharge naturally.
· Figure 13.12
· Satellite photo of crop fields in the U.S. state of Kansas. Center-pivot irrigation uses long, suspended pipes that swing around a central point in each field. Dark green circles are irrigated fields of corn, light green circles are sorghum, and light yellow circles are wheat. Brown areas are fields that have been recently harvested and plowed under. The water used to irrigate these crops is pumped from the Ogallala Aquifer.
·
·
· NASA/GSFC/METI/ERSDAC/JAROS, and U.S./Japan ASTER Science Team
· The Ogallala took about 6,000 years to fill but since 1940s when large-scale irrigation began, its water table levels have declined dramatically. In parts of the southern half of the Ogallala, groundwater is being pumped out 10–40 times faster than the slow natural recharge rate. This has lowered water tables and raised pumping costs, especially in parts of Texas (blowup map in Figure 13.11). The overpumping of this aquifer, along with urban development, restricted access to Colorado River water (Core Case Study), and population growth, have led to a reduced area of irrigated croplands in Texas, Arizona, Colorado, and California. It has also increased competition for water among farmers, ranchers, and growing urban areas.
· Government subsidies—payments or tax breaks designed to increase crop production—have encouraged farmers to grow water-thirsty crops in dry areas, which has accelerated depletion of the Ogallala Aquifer. In particular, corn—a very thirsty crop—has been planted widely on fields watered by the Ogallala. Serious aquifer depletion is also taking place in California’s semiarid Central Valley, the long red area in the California portion of Figure 13.11, which supplies half of the country’s fruits and vegetables.
· The aquifer also supports biodiversity. In various places, groundwater from the Ogallala flows out of the ground onto land or onto lake bottoms through exit points called springs. In some cases, springs feed wetlands, which are vital habitats for many species, especially birds. When the water tables fall, many of these aquatic oases of biodiversity dry out.
· Figure 13.9
· Withdrawing groundwater from aquifers has advantages and disadvantages.
· Critical Thinking:
· Do the advantages outweigh the disadvantages? Why or why not?
·
· Top: Ulrich Mueller/ Shutterstock.com
· Every day, the world withdraws enough freshwater from aquifers to fill a convoy of large tanker trucks that could stretch 480,000 kilometers (300,000 miles)—well beyond the distance to the moon. Test wells and satellite data (Science Focus 13.1) indicate that water tables are falling in many areas of the world because of overpumping. The world’s three largest grain producers—China, the United States, and India—as well as Mexico, Saudi Arabia, Iran, Iraq, Egypt, Pakistan, Spain, and other countries are overpumping many of their aquifers. Much of the Middle East is facing a growing water and food crisis and increasing tensions among its nations, brought on mostly by falling water tables, rapid population growth, and disagreements over access to shared water supplies from the region’s rivers.
· As water tables fall from overpumping, farmers drill deeper wells and buy larger pumps to bring more water to the surface. This process eventually depletes the groundwater in some aquifers or at least removes all the water that can be pumped at an affordable cost.
· For decades, Saudi Arabia has pumped freshwater from a nonrenewable, deep, aquifer. This water is used to irrigate crops such as wheat grown on desert land (Figure 13.10) and to fill fountains and swimming pools, which lose a great deal of water through evaporation into the dry desert air. In 2008, Saudi Arabia announced that irrigated wheat production had largely depleted this major deep aquifer. In 2016, the country stopped producing wheat and imported grain (virtual water) to help feed its 33 million people.
· Figure 13.10
· Natural capital degradation: Satellite photos of farmland irrigated by groundwater pumped from a deep aquifer in a vast desert region of Saudi Arabia between 1986 (left) and 2004 (right). Irrigated areas appear as green dots (each representing a circular spray system). Brown dots show areas where wells have gone dry, and the land has returned to desert. Since 2004, many more wells have gone dry.
·
·
· Left: U.N. Environment Programme and U.S. Geological Survey. Right: U.N. Environment Programme and U.S. Geological Survey.
· Connections
· Aquifer Depletion in California and Meat Consumption in China
· Serious aquifer depletion is also taking place in California’s Central Valley where farmers grow alfalfa as a supplemental feed for cattle and dairy cows. Alfalfa requires more water than any other crop in California. Because alfalfa growers make more money by shipping most of their crop to China, they export billions of gallons of virtual water from this drought-ridden area of California to China to support its growing consumption of meat and milk.
· 13.2cTapping Deep Aquifers
· With global shortages of freshwater looming, scientists are evaluating deep aquifers as future sources of freshwater. Preliminary results suggest that some of these aquifers hold enough freshwater to support billions of people for centuries.
·
However, there are five major problems related to tapping these ancient deposits of freshwater. First, they are nonrenewable on a human time scale. Second, little is known about the geological and ecological impacts of pumping large amounts of freshwater from deep aquifers, especially those located under seabeds. Third, no international treaties govern access to deep aquifers that flow beneath more than one country. Without such treaties, wars could break out over this resource. Fourth, the costs of tapping deep aquifers are unknown and could be high. Fifth, recent research indicates that much of this water is salty and contaminated with arsenic and uranium. In addition, recent research indicates that the supply of freshwater available from renewable aquifers not too far underground is smaller than previous estimates. Thus, our current unsustainable use of many of these aquifers is a serious environmental problem that threatens this vital source of freshwater.
· 13.3a
· Large Dams
· A dam is a structure built across a river to control its flow. Usually, dammed water creates an artificial lake, or reservoir, behind the dam (see chapter-opening photo). The purpose of a dam-and-reservoir system is to capture and store the surface runoff from a river’s watershed, and release it as needed to control floods, to generate electricity (hydropower), and to supply freshwater for irrigation and for towns and cities. Reservoirs also provide recreational activities such as swimming, fishing, and boating. Large dams and reservoirs provide benefits but also have drawbacks (Figure 13.15).
·
· Figure 13.15
· Trade-offs: Large dam-and-reservoir systems have advantages (green) and disadvantages (orange).
·
· Critical Thinking:
· Do the advantages outweigh the disadvantages? Why or why not?
·
· An illustration shows a dam site with hydropower generation, on a three-dimensional surface, where the waters from the river is blocked by a wall with sluice openings through which the excess water flows outside. Hydropower generators looking like rods are shown on the walls over the sluice openings and the electricity generated is taken through wires and connected to a transformer shown behind. Vegetation is found on the banks of the river and pure water is tapped in a reservoir on the banks of the river. Ten callouts are shown in the illustration. The first callout on the left side pointing to the arrangement for irrigation reads, “Provides irrigation water above and below the dam.” The second callout pointing to the reservoir reads, “Provides water for drinking.” The third callout pointing to the dam water reads, “Reservoir useful for recreation and fishing.” The fourth callout pointing to the hydropower generators reads, “Can produce cheap electricity (hydropower).” The fifth callout pointing to the water coming out of the sluice openings reads, “Reduces down-stream flooding of cities and farms.” The sixth callout pointing to the road near the dam water on the right side top reads, “Flooded land destroys forests or cropland and displaces people.” The seventh callout pointing to the dam water reads, “Large losses of water through evaporation.” The eighth callout pointing to the reservoir reads, “Deprives downstream cropland and estuaries of nutrient-rich silt.” The ninth callout pointing to the walls that block the water from the reservoir reads, “Risk of failure and devastating downstream flooding.” The tenth callout pointing to the water flowing through the sluice opening reads, “Disrupts migration and spawning of some fish.” Another insight of the illustration is shown below which shows the reservoir and the dam which are labeled. The intake is indicated by an arrow mark from the reservoir and the water passes through Turbine like a ‘Plus’ symbol and labeled, and then flows outside. Powerhouse is shown just above the turbine and the generated power is taken through power lines connected to transformer.Enlarge Image
· The world’s 45,000 large dams capture and store about 14% of the world’s surface runoff. They provide water for almost half of all irrigated cropland and supply more than half of the electricity used in 65 countries. Dams have increased the annual reliable runoff available for human use by nearly 33%. As a result, the world’s reservoirs now hold 3–6 times more freshwater than the total amount flowing at any moment in all of the world’s natural rivers.
·
· However, dam-and-reservoir systems have drawbacks. For example, the world’s reservoirs have displaced 40-80 million people from their homes and flooded large areas of mostly productive land. Dams have also impaired some of the important ecosystem services that rivers provide (see Figure 8.14, left).
·
· Another effect of dams, along with water withdrawals, is a reduction in the flow of rivers. According to a study by the World Wildlife Fund (WWF) only 21 of the planet’s 177 longest rivers consistently run all the way to the sea before running dry. As a result, aquatic habitat along rivers and at their mouths has been severely degraded (see Case Study that follows). Another effect of diminished river flows, according to the WWF study, is that about one out of five of the world’s freshwater fish and plant species are either extinct or endangered. This helps explain why estimated extinction rates for freshwater life are four to six times larger than for marine or terrestrial species.
·
· Case Study
· How Dams Can Kill a Delta
· Since 1905, the amount of water flowing to the mouth of the Colorado River (Core Case Study) has dropped dramatically. In most years since 1960, the river has barely reached the Gulf of California (Figure 13.16).
·
· Figure 13.16
· The measured flow of the Colorado River (Core Case Study) at its mouth has dropped sharply since 1905 because of multiple dams, water withdrawals for agriculture and urban areas, and prolonged drought.
·
· A graphical representation shows the flow of Colorado River. It is represented with year starting with 1910 and ending with 2000 with an interval of 10 years along the x-axis and flow in (billion cubic meters) starting from 0 and ending at 35 with an interval of 5 along the y-axis. The graph is shaky with several peaks and downfalls. The curve starts from 1910 along the x-axis and 24 along the y-axis and shows several ups and downs and reaches a height of 1935 along the x-axis and above 15 along the y-axis and labeled as, “Hoover dam completed 1935.” The graph again shows ups and downs and touches the x-axis just before 1960 and shows slight rise and then slopes down again and touches x-axis at 1963 and labeled above as, “Glen Canyon dam completed 1963.” Then the graph continues over the x-axis until 1980 and then shows ups and downs till it reaches 2000 along the x-axis. In between there is light peak that reaches 15 along the y-axis and above 1980 on x-axis. The curve touches the x-axis again at the end.
· (Compiled by the authors using data from the U.S. Geological Survey)
· The Colorado River once emptied into a vast delta, with forests, lagoons, and marshes rich in plant and animal life. The delta also supported a thriving coastal fishery for hundreds of years. Since the damming of the Colorado River—within one human lifetime—this biologically diverse delta ecosystem has collapsed and is now covered mostly by mud flats and desert.
·
· Historically, about 80% of the water withdrawn from the Colorado has been used to irrigate crops and raise cattle. That is because the U.S. government (taxpayers) paid for the dams and reservoirs and have supplied many farmers and ranchers with water at low prices. These subsidies have led to wasteful use of irrigation water for growing thirsty crops such as rice, cotton, almonds, and alfalfa in dry areas.
·
· In 2014, the floodgates of the Morelos Dam near Yuma, Arizona, were opened for 2 months to send Colorado River water through the delta to the Gulf of California for the first time in years. Researchers are evaluating the effects of this experiment, but short-term results were dramatic, according to National Geographic Fellow and water policy expert Sandra Postel. Thousands of trees began to grow along the river’s banks and groundwater in the delta area was partially recharged for the first time in many years.
·
·
·
· Water experts urge the seven states using the Colorado River to enact and enforce strict water conservation measures. They also call for sharply decreasing or phasing out state and federal government subsidies for agriculture in this region. The goal would be to shift water-thirsty crops to less arid areas and severely restrict the watering of golf courses and lawns in the desert areas of the Colorado River basin. They suggest that the best way to implement such solutions is to sharply raise the historically low price of the river’s freshwater over the next decade—another application of the full-cost pricing principle of sustainability.
·
· In 2019, the seven western states sharing the Colorado River agreed on a plan to voluntarily cut their water use from the river to prevent the federal government from imposing mandatory levels on the amount of water they could withdraw from the river. This is an important step but much more needs to be done according to water experts, as discussed above.
·
· Critical Thinking
· What are three steps you would take to deal with the problems of the Colorado River system?
·
· Reservoirs also have limited lifespans. Within 50 years, reservoirs behind dams typically fill up with sediments (mud and silt), which make them useless for storing water or producing electricity. In the Colorado River system (Core Case Study), the equivalent of roughly 20,000 dump-truck loads of silt are deposited on the bottoms of the Lake Powell and Lake Mead reservoirs every day. Sometime during this century, these two vital reservoirs will very likely be too full of silt to function as designed. About 85% of all U.S. dams will be 50 years old or older by 2025. Some aging dams have been removed because their reservoirs have filled with silt.
·
· If climate change occurs as projected during this century, water shortages will intensify in many parts of the world. For example, mountain snows that feed the Colorado River system will melt faster and earlier, making less freshwater available to the river system when it is needed for irrigation during hot and dry summer months. Agricultural production would drop sharply and the region’s major desert cities such as Las Vegas, Nevada and Phoenix, Arizona, would be challenged to survive.
·
· If some of the Colorado River’s largest reservoirs keep dropping dramatically or become filled with silt during this century, the region will experience costly water and economic disruptions. For example, by 2013, the water level in Lake Mead had dropped below the Hoover Dam’s intake pipes. The city of Las Vegas has spent more than $800 million to build lower intake pipes in order to maintain hydroelectric production.
·
· Dams can also fail and flood downstream areas. According to the U.S. Army Corps of Engineers, 30% of the more than 90,000 dams in the United States are at risk of failure and need repairs.
·
· Nearly 3 billion people in South America, China, India, and other parts of Asia—that is, nearly half the world’s population—depend on river flows fed by mountain glaciers. The glaciers serve as freshwater savings accounts. They store ice and snow in wet periods and release it slowly during dry seasons for use on farms and in cities. In 2015, according to the World Glacier Monitoring Service, many of these mountain glaciers have been shrinking for 24 consecutive years, mostly due to a warming atmosphere.
·
· 13.3b
· Removing Salt from Seawater to Provide Freshwater
· Desalination is the process of removing dissolved salts from ocean water or from brackish (slightly salty) water in aquifers or lakes. It is another way to increase supplies of freshwater.
·
· Currently, the two most widely used methods for desalinating water are distillation and reverse osmosis (Figure 13.17). Distillation involves heating saltwater until it evaporates (leaving behind salts in solid form) and condenses as freshwater. Reverse osmosis (or microfiltration) uses high pressure to force saltwater through a membrane filter with pores small enough to remove the salt and other impurities. Reverse osmosis requires less than a third of the energy needed to distill saltwater.
·
· Figure 13.17
· Desalination: Reverse osmosis (left) involves applying high pressure (a) to force sea water from one chamber into another through a semipermeable membrane (b) that separates the salt (c) producing freshwater (d). Distillation (right) involves heating seawater (a) to produce steam (b) which is then condensed (c) and collected as freshwater (d) while brine is also collected (e) for processing.
·
· An illustration shows two images. The first illustration shows reverse osmosis which shows two chambers separated by a semipermeable membrane. The sea water in one of the chambers on the left side is given high pressure from upward, indicated by arrow marks pointing downward and labeled as a. The sea water is forced through the semi-permeable membrane which is indicated through the arrow marks and labeled as b. Fresh water production on the left, is labeled as c and indicated by arrow mark with opening. The level of water in the next chamber is low and process is continued which is distillation indicated as d with an opening chamber on the right side. The second illustration shows distillation which shows two chambers in a container. In the right chamber, the water is heated which is indicated by a circular rod-like structure in red and labeled as a. The steam generated is condensed which is indicated by a spiral rod moving from the heated water towards upward and then to the next chamber and labeled as b, where the condensation starts above the heating process. Then the water droplets are shown in the next chamber, on left which is the fresh water and labeled as c. The brine which is collected is indicated with an outlet of the chamber is labeled as d. The outlet of the hot chamber shows an arrow mark pointing outward on the right side near the heating rod and labeled as e.Enlarge Image
· The world’s more than 18,400 desalination plants, including more than 320 in the United States, supply less than 1% of the freshwater used in the United States and in the world.
·
· Three major problems hinder the widespread use of desalination.
·
· It is costly because removing salt from seawater requires a lot of energy.
·
· Pumping large volumes of seawater through pipes requires chemicals to sterilize the water and prevent algae growth. This kills many marine organisms and requires large inputs of energy and money.
·
· Desalination produces huge quantities of wastewater that are much saltier than ocean water and that require proper disposal. Dumping the salty waste into coastal ocean waters increases the salinity of those waters, which can threaten food resources and aquatic life. Disposing the salty wastes on land can contaminate groundwater and surface water.
·
· Currently, desalination is practical only for water-short countries and cities that can afford its high cost. However, scientists and engineers are working to develop better and more affordable desalination technologies. (Science Focus 13.2)
·
· Science Focus 13.2
· The Search for Better Desalination Technology
· Reverse osmosis (Figure 13.17, left) is the favored desalination technology because it requires much less energy than distillation, but it is still energy intensive. Much of the scientific research in this field is aimed at improving the membrane and the pre- and post-treatment processes to make desalination more energy efficient. Scientists are working to develop new, more efficient and affordable membranes that can separate freshwater from saltwater under lower pressure, which would require less energy.
·
· One promising material that might serve this purpose is one-atom-thick graphene. Such technological advances have brought the cost of desalination down, but not enough yet to make it affordable or useful for large-scale irrigation or to meet much of the world’s demand for drinking water.
·
·
·
· A team of scientists at the Massachusetts Institute of Technology (MIT), led by Martin Z. Bazant, is evaluating the use of an electric shock to separate saltwater and freshwater. Scientists are also considering ways to use solar and wind energy—applying one of the three scientific principles of sustainability—in combination with conventional power sources to help bring down the cost of desalinating seawater. Saudi Arabia has the world’s largest solar-powered desalination project. It uses concentrated solar energy to power new filtration technology at a plant that will meet the daily water needs of 100,000 people. Two Australian companies, Energetech and H2AU, have joined forces to build an experimental desalination plant that uses the power generated by ocean waves to drive reverse-osmosis desalination. This approach produces no air pollution and uses renewable energy.
·
· Some scientists argue for building fleets of such floating desalination plants. They could operate out of sight from coastal areas and transfer the water to shore through seabed pipelines or in food-grade shuttle tankers. Because of their distance from shore, the ships could draw water from depths below where most marine organisms are found. The resulting brine could be returned to the ocean and diluted far away from coastal waters.
·
· These methods would cut the costs of desalination, but they would still be high. Analysts expect desalination to be used more widely in the future, as water shortages become worse. However, there is still a lot of research to do before desalination can become an affordable major source of freshwater. GREEN CAREER: Desalination engineer
·
· Critical Thinking
· Do you think that improvements in desalination will justify highly inefficient uses of water, such as maintaining swimming pools, fountains, and golf courses in desert areas? Why or why not?
·
·
Learning from Nature
· Scientists are trying to develop more efficient and affordable ways to desalinate seawater by mimicking how our kidneys take salt out of water and how fish in the sea survive in saltwater. 13.4a
· Water Transfers Have Benefits and Drawbacks
· In some heavily populated dry areas of the world, governments have tried to solve water shortage problems by using canals and pipelines to transfer water from water-rich areas to water-poor areas. Much of this water is transferred for irrigating crops. For example, if you eat lettuce in the United States, chances are it was grown in the arid Central Valley of California, partly with the use of irrigation water from snow melting off the tops of the High Sierra Mountains of northeastern California.
·
· The California State Water Project (Figure 13.18) is one of the world’s largest freshwater transfer projects. It uses a maze of giant dams, pumps, and lined canals, or aqueducts (photo in Figure 13.18), to transfer freshwater from the mountains of northern California to heavily populated cities and agricultural regions of water-poor central and southern California.
·
· Figure 13.18
· The California State Water Project transfers huge volumes of freshwater from one watershed to another. The arrows on the map show the general direction of water flow. The photo shows one of the aqueducts carrying water within the system.
·
· Critical Thinking:
· What effects might this system have on the areas from which the water is taken?
·
· A map shows California state water project, where California, Shasta lake, Sacramento river, Sacramento, lake Tahoe, Oroville dam and reservoir, San Luis dam and reservoir, Sierra mountain range, San Joaquin river, Fresno, Santa Barbara, Los Angeles, San Diego, Nevada, San Francisco, and Hoover dam and reservoir are labeled. The Colorado River, the Colorado River aqueduct, North Bay aqueduct, south bay aqueduct, California aqueduct, and Los Angeles aqueduct are shaded with a red line and labeled. A photo on the top of the map, shows a river and dry land on both sides of the river, along with the bridge over it.Enlarge Image
· Sarahleen/National Geographic Image Collection
· This massive water transfer has yielded many benefits. California’s heavily irrigated Central Valley supplies half of the nation’s fruits and vegetables, and the arid cities of San Diego and Los Angeles have grown and flourished because of the water transfer.
·
· However, water transfers can also have high environmental, economic, and social costs (see Case Study that follows). They usually involve large water losses, through evaporation and leaks in the water-transfer systems. They also degrade ecosystems in areas from which the water is taken. For example, the Chinese government is implementing its South–North Water Diversion Project to transfer water from the Yangtze River in southern China to the thirsty north. China’s massive water transfer will displace more than 350,000 villagers who will have to move from lands they have farmed for generations. In addition, scientists warn that removing huge volumes of water from the Yangtze River could severely damage its ecosystem, which has been suffering from its worst drought in 50 years.
·
· Case Study
· The Aral Sea Disaster: An Example of Unintended Consequences
· The shrinking of the Aral Sea (Figure 13.19) is the result of a water transfer project in central Asia. Starting in 1960, enormous amounts of irrigation water were diverted from the two rivers that supply water to the Aral Sea. The goal was to create one of the world’s largest irrigated areas, mostly for raising cotton and rice. The irrigation canal, the world’s longest, stretches more than 1,300 kilometers (800 miles).
·
· Figure 13.19
· Natural capital degradation: The Aral Sea, straddling the borders of Kazakhstan and Uzbekistan, was one of the world’s largest saline lakes. These satellite photos show the sea in 1976 (left) and in 2016 (right). The shrinkage of the southern Aral Sea has continued since 2016.
·
· Critical Thinking:
· What do you think should be done to help prevent further shrinkage of the Aral Sea?
·
· A figure shows two photos. The first photo shows the complete Aral Sea which was in existence during 1976 on the left side. The second photo shows the shrunken Aral Sea which shows only a few portions of the Aral Sea which was in existence during 2015 on the right side.Enlarge Image
· WorldSat International, Inc. All rights reserved; NASA
· This project, coupled with drought and high evaporation rates due to the area’s hot and dry climate, has caused a regional ecological and economic disaster. Since 1961, the sea’s salinity has risen sevenfold and the average level of its water has dropped by an amount roughly equal to the height of a six-story building. The Southern Aral Sea has lost 90% of its volume of water and most of its lake bottom is now a white salt desert (Figure 13.19, right photo). Water withdrawals have reduced the two rivers feeding the sea to mere trickles.
·
· About 85% of the area’s wetlands have been eliminated and about half the local bird and mammal species have disappeared. The sea’s greatly increased salt concentration—three times saltier than ocean water—has caused the presumed local extinction of 26 of the area’s 32 native fish species. This has devastated the area’s fishing industry, which once provided work for more than 60,000 people. Fishing villages and boats once located on the sea’s coastline now sit abandoned in a salty desert.
·
· Winds pick up the sand and salty dust and blow it onto fields as far as 500 kilometers (310 miles) away. As the salt spreads, it pollutes water and kills wildlife, crops, and other vegetation. Aral Sea dust settling on glaciers in the Himalayas is causing them to melt at a faster-than-normal rate.
·
· The shrinkage of the Aral Sea has also altered the area’s climate. The shrunken sea no longer acts as a thermal buffer to moderate the heat of summer and the extreme cold of winter. There is less rain, summers are hotter and drier, winters are colder, and the growing season is shorter. The combination of such climate change and severe salinization has reduced crop yields by 20–50% on almost one-third of the area’s cropland—the opposite of the project’s intended effects.
·
· Since 1999, the UN, the World Bank, and the five countries surrounding the lake have worked to improve irrigation efficiency. They have also partially replaced thirsty crops with other crops that require less irrigation water. Because of a dike built to block the flow of water from the Northern Aral Sea into the southern sea, the level of the northern sea has risen by 2 meters (7 feet), its salinity has dropped, dissolved oxygen levels are up, and it supports a healthy fishery. However, the formerly much larger southern sea is still shrinking and is likely to dry up completely within a few years.
·
· Other large lakes are also drying up. They include Bolivia’s Lake Poopó, Iran’s Lake Urmia, and Lake Chad located in several West African countries.
·
· In California, sending water south has reduced the flow of the Sacramento River, threatening fisheries and reducing the flushing action that helps to cleanse the San Francisco Bay of pollutants. As a result, the bay has suffered from pollution, and the flow of freshwater to its coastal marshes and other ecosystems has dropped. These factors have placed stress on wildlife species that depend on the bay’s many ecosystems. Water was also diverted from streams that flow into Mono Lake, an important feeding stop for migratory birds. This lake experienced an 11-meter (35-foot) drop in its water level before the diversions were stopped. For a while, the lake’s entire ecosystem was in jeopardy.
·
· The federal government and the state of California subsidized this water transfer project. These subsides have promoted inefficient use of large volumes of water to irrigate thirsty crops such as lettuce, alfalfa, and almonds in desert-like areas. In central California, agriculture consumes three-fourths of the water that is transferred. Much of this water is wasted by inefficient irrigation systems. Studies show that making irrigation just 10% more efficient would provide all the water needed for domestic and industrial uses in southern California.
·
According to several studies, climate change during this century will make matters worse in California by reducing surface water availability. California depends on snowpacks, bodies of densely packed, slowly melting snow in the High Sierra Mountains, for more than 60% of its freshwater during summer according to the Sierra Nevada Conservancy. Projected atmospheric warming could shrink the snowpacks by as much as 40% by 2050 and by as much as 90% by the end of this century. This will sharply reduce the amount of freshwater available for northern California residents and ecosystems, as well for the transfer of water to central and southern California. 13.5aCutting Water Waste
According to water resource expert Mohamed El-Ashry of the World Resources Institute, about 66% of the freshwater used in the world and about 50% of the freshwater used in the United States is lost through evaporation, leaks, and inefficient use. El-Ashry estimates that it is economically and technically feasible to reduce such losses to 15%, thereby meeting most of the world’s future freshwater needs.
Why do we have such large losses of freshwater? According to water resource experts, there are two major reasons. First, the cost of freshwater to most users is low due mostly to government subsidies—a violation of the full-cost pricing principle of sustainability. This gives users little or no financial incentive to invest in water-saving technologies.
Higher prices for freshwater encourage water conservation but make it difficult for low-income farmers and city dwellers to buy enough water to meet their needs. When South Africa raised water prices, it dealt with this problem by establishing lifeline rates, which give each household a set amount of free or low-priced water to meet basic needs. When users exceed this amount, they pay increasingly higher prices as their water use increases. This is a user-pays approach.
The second major cause of unnecessary waste of freshwater is a lack of government subsidies for improving the efficiency of water use. Many hydrologists and economists call for replacing current water subsidies that encourage water waste with subsidies that would encourage using water more efficiently. Understandably, farmers and industries that receive subsidies that keep water prices low have vigorously opposed efforts to eliminate or reduce them.
· 13.5b
· Improving Irrigation Efficiency
·
·
· Since 1980, the amount of food that can be grown per drop of water has roughly doubled. In addition, since the 1970s, the amount of water used per person in the United States has dropped by about 33%, after rising for decades. Most of these water savings have come from improvements to irrigation efficiency in the United States and other more-developed countries.
·
· However, there is still a long way to go, especially in less-developed countries. Only about 60% of the world’s irrigation water reaches crops, which means that most irrigation systems are highly inefficient. The least inefficient irrigation is flood irrigation, in which water is pumped from a groundwater or surface water source through unlined ditches where it flows by gravity to the crops being watered (Figure 13.20, left). This method delivers far more water than is needed for crop growth, and typically, about 45% of it is lost through evaporation, seepage, and runoff.
·
· Figure 13.20
· Traditional irrigation methods rely on gravity and flowing water (left). Newer systems such as center-pivot, low-pressure sprinkler irrigation (right) and drip irrigation (center) are far more efficient.
·
· An illustration shows three sections. The first section shows the crops or plants planted on the soil in rows which is shown on a three-dimensional surface and the text below reads, “Gravity Flow (Efficiency 60% and 80% with surge values), Water usually comes from an aqueduct system or a nearby river.” The second section shows the trees being planted in rows and columns and for each tree a circular rod-like structure is placed around and the circular rods are interconnected by horizontal and vertical rods forming a newer system of irrigation called, “drip irrigation.” The text below reads, “Drip Irrigation (efficiency 90-95%), above or below ground pipes or tubes deliver water to individual plant roots.” The third section shows the crops being planted in a circular pattern on a three-dimensional surface and irrigated through pipes from the top which are supported by the pivot at the center. The insight of this illustration is shown above, which is indicated by an arrow mark from the center pivot, shows a plane surface where the crops are planted and the water is sprinkled from above through pipes on each row, from the rod structure which is held in a horizontal position through a vertical rod support. The text below reads, “Centre pivot (efficiency 80% with low pressure sprinkler and 90-95% LEPA sprinkler), Water usually pumped from underground and sprayed from mobile boom with sprinklers.”Enlarge Image
· Another inefficient system is the traditional spray irrigation system, a widely used tool of industrialized crop production. It sprays huge volumes of water onto large fields, and as much as 40% of this water is lost to evaporation, especially in dry and windy areas, according to the U.S. Geological Survey (USGS). These systems are commonly used in the Midwestern United States and have helped to draw down the Ogallala Aquifer (Case Study, this chapter).
·
· More efficient irrigation technologies greatly reduce water losses by delivering water more precisely to crops—a more crop per drop strategy. For example, a center-pivot, low-pressure sprinkler (Figure 13.20, right), which uses pumps to spray water on a crop, allows about 80% of the water to reach crops. An improved center-pivot system that sprays the water closer to the ground puts 90–95% of the water where crops need it.
·
· Drip, or trickle irrigation (Figure 13.20, center), is the most efficient way to deliver small amounts of water precisely to crops. It consists of a network of perforated plastic tubing installed at or below the ground level. Small pinholes in the tubing deliver drops of water at a slow and steady rate, close to the roots of individual plants and 90–95% of the water to reaches the crops.
·
· Drip irrigation is used on less than 5% of the irrigated crop fields in the world and in the United States, largely because most drip irrigation systems are costly. This percentage rises to 13% in the U.S. state of California, 66% in Israel, and 90% in Cyprus. If freshwater were priced closer to the value of the ecosystem services it provides, and if government subsidies for inefficient use of water were reduced or eliminated, drip irrigation could be used to irrigate most of the world’s crops. For farmers receiving irrigation water subsidies, it is cheaper to waste water than to conserve it.
·
· According to the UN, reducing the current global withdrawal of water for irrigation by just 10% would save enough water to grow crops and meet the estimated additional water demands of the earth’s cities and industries through 2025. This would also reduce the need for costly desalination.
3.5c
Conserving Water through Low-Tech Methods
Many of the world’s poor farmers use low-cost, traditional irrigation technologies that are more sustainable than most large-scale irrigation systems. For example, millions of farmers in Bangladesh and other countries where water tables are high use human-powered treadle pumps to bring groundwater up to the earth’s surface and into irrigation ditches (
Figure 13.21
). These wooden devices are inexpensive and easy to build from local materials. One such pump developed by the nonprofit International Development Enterprises (IDE) uses 60–70% less water than a conventional gravity-flow system to irrigate the same amount of cropland at one-tenth the cost of conventional drip systems.
Figure 13.21
Solutions: In areas of Bangladesh and India, where water tables are high, many small-scale farmers use treadle pumps to supply irrigation water to their fields.
A photo shows a field in which men, and women are working and on the left corner, a treadle pump with a girl standing on it and the pump’s water supply is shown.
Courtesy of International Development Enterprises
Other farmers in some less-developed countries use buckets, small tanks with holes, or simple plastic tubing systems for drip irrigation. One ingenious system makes use of solar energy to drive drip irrigation (
Individuals Matter 13.1
).
Individuals Matter 13.1
Jennifer Burney: Environmental Scientist and National Geographic Explorer
A photo shows Jennifer Burney, who is an Environmental Scientist and National Geographic Explorer.
UC San Diego/National Geographic Image Collection
Environmental scientist and National Geographic Explorer Jennifer Burney notes that subsistence farmers represent the majority of the world’s poorest people and need to boost their productivity for better standards of living and health. She is trying to help such farmers in Africa to grow, distribute, and cook their food using resources such as water, fertilizer, and energy as efficiently as possible. She also helps them avoid unsustainable practices such as wasteful irrigation and fertilizer runoff that are the legacy of large-scale industrial farming in the developed world.
For example, in arid sub-Saharan Africa, farmers must depend on rainfall for raising crops on small plots because only 20% of the rainfall flows into streams and aquifers while the rest evaporates. Overpumping can quickly deplete the groundwater. These factors, worsened by drought, make it hard for farmers to feed their families.
To deal with this problem, Burney has helped farmers to connect two technologies—solar energy systems and drip irrigation. Drip irrigation systems sip water and drip it directly onto plant roots instead of pumping and dumping it. Solar-powered pumps work without the need for batteries or fuel. On sunny days, when crops need water more, the solar panels speed the pumping; on cloudy days when there is less evaporation, the pumping slows down. Thus, only the amount of water that is needed is pumped on most days. This has allowed farmers to grow fruits and vegetables on a larger scale and to improve their incomes and food security.
Rainwater harvesting is another simple and inexpensive way to provide water. It involves using pipes from rooftops and channels dug in the ground to direct rainwater that would otherwise run off the land. It can be stored in underground or aboveground storage tanks (cisterns), ponds, and plastic barrels for use during dry seasons. This is especially useful in countries such as India, where much of the rain comes in a short monsoon season.
In dry mountainous coastal areas, such as in Peru, some communities are capturing water from fog that rolls in off the ocean on most days. On the seaward hillsides, they erect large flat nets on which the fog condenses. The resulting water drops roll off the nets into troughs that channel the water into holding tanks.
Other strategies used by poor farmers to increase the amount of crop per drop of rainfall include polyculture farming to create more canopy cover and reduce evaporative water losses; planting deep-rooted perennial crop varieties (see Figure 12.D); controlling weeds; and mulching fields to retain more moisture.
Figure 13.22
summarizes several ways to reduce water losses in crop irrigation. Since 1950, Israel has used many of these techniques to slash irrigation water losses by 84% while irrigating 44% more land. Israel now treats and reuses 30% of its municipal sewage water for crop production and plans to increase this to 80% by 2025. Israel also uses desalination to provide nearly half of its water. The government also gradually eliminated most water subsidies to raise Israel’s price of irrigation water, which is now one of the highest in the world.
Figure 13.22
Ways to reduce freshwater losses in irrigation.
Critical Thinking:
Which two of these solutions do you think are the best ones? Why?
An illustration provides information about Reducing Irrigation Water Losses in bullet points and the text below reads, “Avoid growing thirsty crops in dry areas, import water-intensive crops and meat, encourage organic farming and polyculture to retain soil moisture, monitor soil moisture to add water only when necessary, expand use of drip irrigation and other efficient methods, irrigate at night to reduce evaporation, line canals that bring water to irrigation diches, and irrigate with treated wastewater.”
13.5dCutting Freshwater Waste in Industries and Homes
Producers of chemicals, paper, oil, coal, primary metals, and processed foods consume almost 90% of the freshwater used by industries in the United States. The pulp and paper industry uses more water to produce a ton of product than any other industry. Some of these industries recapture, purify, and recycle water to reduce their water use and water treatment costs. For example, more than 95% of the water used to make steel can be recycled. Even so, most industrial processes could be redesigned to use much less water. GREEN CAREER: Water conservation specialist
Flushing toilets with freshwater—most of it clean enough to drink—is the single largest use of domestic freshwater in the United States and accounts for about one-fourth of home water use. Since 1992, U.S. government standards have required that new toilets use no more than 6.1 liters (1.6 gallons) of water per flush. Even at this rate, just two flushes of such a toilet use more than the daily amount of water available for all uses to many of the world’s poor people living in arid regions.
Other water-saving appliances are widely available. Low-flow showerheads can save large amounts of water by cutting the flow of a shower in half. Front-loading clothes washers use 30% less water than top-loading machines use. According to the American Water Works Association, the typical American household could cut its daily water use and water costs by nearly a third by using water-saving appliances and stopping water leaks.
According to UN studies, 30–60% of the water supplied in nearly all of the world’s major cities in less-developed countries is lost, primarily through leakage from water mains, pipes, pumps, and valves. Water experts say that fixing these leaks should be a high priority for water-short countries, because it would increase water supplies and cost much less than building dams or importing water.
Even in advanced industrialized countries such as the United States, losses to leakage average about 16%. However, leakage losses have been reduced to about 3% in Copenhagen, Denmark, and to less than 3% in Fukuoka, Japan. In one year, a faucet leaking water at the rate of 1 drop per second can waste 10,000 liters (2,650 gallons). Not detecting and fixing water leaks from faucets, pipes, and toilets is equivalent to burning money.
Many homeowners and businesses in water-short areas are using drip irrigation on their properties to cut water losses. Some use smart sprinkler systems with moisture sensors that cut water used for watering lawns by up to 40%. Others are copying nature by replacing green lawns with a mix of native plants that need little or no watering (
Figure 13.23
). Such water-thrifty landscaping saves money by reducing water use by 30–85% and by sharply reducing labor, fertilizer, and fuel requirements. It also can help landowners to reduce polluted runoff, air pollution, and yard wastes.
Figure 13.23
This yard in a dry area of the southwestern United States uses a mix of plants that are native to the arid environment and require little watering.
karolinapatryk/Thinkstock
According to a satellite study by NASA scientist Christina Miles, grass lawns are America’s largest irrigated crops. However, some communities and housing developments in water-short areas in the United States have passed ordinances that require green lawns and prohibit the planting of native vegetation in place of lawns.
Some water used in homes can be reused.
Gray water
is used water from bathtubs, showers, sinks, dishwashers, and clothes washers. About 50-75% of a household’s gray water could be stored in a holding tank and reused to irrigate lawns and nonedible plants, flush toilets, and wash cars. Such efforts mimic the way nature recycles water, and thus they follow the chemical cycling principle of sustainability.
Large-scale harvesting of rainwater in urban areas can increase water supplies and reduce flooding by reducing storm flows. In Singapore, for example, most urban runoff is collected and deposited in reservoirs.
The low cost of water in most communities is one of the major causes of excessive water use and waste. About one-fifth of all U.S. public water systems do not use water meters, which can help track water use and reveal leaks. These public water systems charge a single low annual rate for almost unlimited use of high-quality water.
When the U.S. city of Boulder, Colorado, introduced water meters, water use per person dropped by 40%. In some cities in Brazil, people buy smart cards, each of which contains a certain number of water credits that entitle their owners to measured amounts of freshwater. Brazilian officials say this approach saves water and typically reduces household water bills by 40%. However, an estimated 40% of Brazil’s freshwater is lost to leaks and theft.
Figure 13.24
summarizes various ways to use water more efficiently in industries, homes, and businesses.
Figure 13.24
Ways to reduce freshwater losses in industries, homes, and businesses.
Critical Thinking:
1. Which three of these solutions do you think are the best ones? Why?
Finding more sustainable ways to use freshwater is the subject of some major research efforts (see
Case Study
that follows). One group that is working on this problem is the Global Water Policy Project, founded by the renowned water supply expert and National Geographic Explorer Sandra Postel (
Individuals Matter 13.1
). Each of us can reduce our water footprints by cutting our use and waste of water (
Figure 13.25
).
Figure 13.25
Individuals matter: You can reduce your use and waste of freshwater.
Question:
1. Which of these steps have you taken? Which would you like to take?
Case Study
How Californians Have Dealt with Water Woes
In 2015, the state of California had been experiencing drought for four years and projected climate change is likely to make the state hotter and drier throughout much of this century. California is also likely to have more extreme weather events, including large flooding episodes and more intense droughts.
In some areas of California, the effects of drought include dwindling aquatic ecosystems and municipal water supplies, increasingly frequent wildfires, crop losses, and parched lawns. In 2014, NASA satellite data showed the state’s major river basins to be well below normal (
Figure 13.26
). In 2015, the Sierra Nevada snowpack, which has provided a third to half of the state’s water supply in the past, was just 5% of its historical average size. By late 2015, the drought across 97% of the state was classified as severe or worse.
Figure 13.26
One of California’s major reservoirs, Lake Oroville, dropped dramatically between 2011 (left) and 2014 (right), due largely to drought.
Justin Sullivan/Getty Images News/Getty Images
According to the Natural Resources Defense Council (NRDC), agriculture uses 78% to 80% of California’s available water in most years. Due to water restrictions imposed by the state in 2013, along with water rights laws, some Central Valley farmers have lost their surface water irrigation sources. In turn, many have drilled deeper wells into the valley’s aquifers that require decades to recharge. Hydrologists see this overpumping of the aquifers as unsustainable in the long term.
To deal with these problems, California raised water prices, with heavy users paying more. According to the Public Policy Institute of California, at least 40% of residential water use is for watering lawns. The next three largest uses are for swimming pools, toilets, and showers. Many Californians are replacing their grass lawns with water-saving ground cover or native vegetation adapted to dry conditions (
Figure 13.23
). Others are installing more efficient toilets and showerheads and are showering and washing clothes less frequently. By 2015, California’s urban residents reached a 25% water use reduction goal set by the state government.
Another proposed strategy is for farmers to shift from producing thirsty crops such as alfalfa, lettuce, and almonds, to producing less water-intensive crops. The Public Policy Institute of California estimated that the amount of water used to grow almonds in 2013 was larger than that used by all homes and businesses in San Francisco and Los Angeles combined. In addition, California is the leading dairy state and dairy products are among the most water-intensive. It has been estimated that the average American consumes 1,132 liters (300 gallons) of California water every week by eating foods produced in the state.
Desalination is another option that many are promoting (
Science Focus 13.2
). In 2015, the largest desalination plant in the western hemisphere was opened in Carlsbad, north of San Diego. It was designed to supply 300,000 state residents with freshwater. However, because of current high costs and potentially harmful environmental effects, desalination is a controversial and limited solution to water shortages.
Another strategy is restoring wastewater to drinking water quality. Orange County’s Groundwater Replenishment System takes sewer and other wastewater and processes it to the point where it exceeds all state and federal drinking water standards. It meets the needs of about 600,000 people. Water can also be reused through gray water systems. Many homes in California are equipped with new purple pipes—special pipes built in for this purpose.
13.5e
Using Less Water to Remove Wastes
Currently, we use large amounts of freshwater to flush away industrial, animal, and household wastes. According to the UN Food and Agriculture Organization (FAO), if current growth trends in population and water use continue, within 40 years, the equivalent of the world’s entire reliable flow of river water will be needed just to dilute and transport such wastes.
Recycling and reusing gray water from sewage plants could save much of this freshwater. In Singapore, all sewage water is treated at reclamation plants for reuse by industry. U.S. cities such as Las Vegas, Nevada, and Los Angeles, California, are also beginning to clean up and reuse some of their wastewater. However, less than 10% of the water in the United States is recycled, cleaned up, and reused. Sharply raising this percentage would be a way to apply the chemical cycling principle of sustainability.
Another way to keep freshwater out of the waste stream is to rely more on waterless composting toilets. These devices convert human fecal matter to a small amount of dry and odorless soil-like humus material that can be removed from a composting chamber and returned to the soil as fertilizer. One of the authors (Miller) used a composting toilet for over a decade with no problems, while living and working deep in the woods in a small passive solar home and office used for evaluating solutions to water, energy, and other environmental problems (see p. xxxiii).
As water shortages grow in many parts of the world, people are using methods discussed here to use water more sustainably. Their experiences can be instructive to people who want to avoid water shortages in the first place.
Learning from Nature
The leaves of the Lotus flower do not absorb water. Tiny bumps on a lotus leaf, coated with a natural waxy material, cause water to roll off, taking any dirt particles with it, which makes the leaf self-cleaning. Scientists have mimicked this effect to create a water-, fat-, and oil-repellant sealant that can be sprayed onto a surface. This could allow for making self-cleaning products that would require little or no water for cleaning. 13.6a
Some Areas Get Too Much Water
Some areas have too little freshwater. Other areas sometimes have too much because of natural flooding by streams, caused mostly by heavy rain or rapidly melting snow. A flood happens when freshwater in a stream overflows its normal channel and spills into an adjacent area, called a floodplain.
Natural flooding, which occurs on many streambeds every spring, provides several benefits. It has created some of the world’s most productive farmland by depositing nutrient-rich silt on floodplains. It also helps recharge groundwater and refill wetlands that are commonly found on floodplains, thereby supporting biodiversity and aquatic ecosystem services.
People settle on floodplains to take advantage of their many assets such as fertile soil suitable for crops, but certain human activities have led to increased flooding in many areas. Major floods kill thousands of people every year and cost tens of billions of dollars in property damage (see the Case Study that follows). Such floods are usually considered natural disasters, but since the 1960s, human activities have contributed to a sharp rise in flood deaths and damages, meaning that such disasters are partly caused by human actions.
Case Study
Living Dangerously on Floodplains in Bangladesh
Bangladesh is one of the world’s most densely populated countries. In 2018, its 166 million people were packed into an area roughly the size of the U.S. state of Wisconsin (which has a population of less than 6 million). In addition, the country’s population is projected to increase to 202 million by 2050. Bangladesh is a flat country, only slightly above sea level, and it is one of the world’s poorest countries.
The people of Bangladesh depend on moderate annual flooding during the summer monsoon season to grow rice and help maintain soil fertility in their country’s delta basin region, which is fed by numerous river systems. The annual floods also deposit eroded Himalayan soil on the country’s crop fields. Bangladeshis have adapted to moderate flooding. Most of the houses have flat thatch roofs on which families can take refuge with their belongings in case of rising waters. The roofs can be detached from the walls, if necessary, and floated like rafts. After the waters have subsided, the roof can be reattached to the walls of the house. However, great floods can overwhelm such defenses.
In the past, great floods occurred every 50 years or so. However, between 1987 and 2017 there were eight severe floods, each covering a third or more of the country with water. Bangladesh’s flooding problems begin in the Himalayan watershed, where rapid population growth and unsustainable farming have resulted in deforestation. Monsoon rains now run more quickly off the barren Himalayan foothills, carrying vital topsoil with them (
Figure 13.27
, right).
Figure 13.27
Natural capital degradation: A hillside before and after deforestation.
Question:
How might a drought in this area make these effects even worse?
An illustration shows two models, one for forested hill-side and the other for After Deforestation. An illustration for forested hillside shows a lake, crops cultivated in agricultural land, and a grassland at the base of the hill and along the elevation of the hill-side, numerous trees are shown. Cloud mass is shown above the hill from which raining is shown. Arrow marks pointing upwards from the hillside is shown and the text beside reads, “Evapotranspiration.” The agricultural land is labeled. The text over the hill-side reads, “Diverse Ecological Habitat.” A callout pointing to the tree roots reads the text, “Tree roots stabilize soil.” A callout pointing to the grasslands reads the text, “Vegetation releases water slowly and reduces flooding.” The text beside the model reads, “Trees reduce soil erosion from heavy rain and wind.” An illustration on the right side, shows After Deforestation displaying the hillside which is covered with trees as well as roads and at the base of the hillside are the lake, grasslands, and agricultural land. Along the slope of the hillside, gullies and landslides are shown and labeled. The grasslands are shown as bare lands and labeled as, “Heavy rain erodes top soil.” The lake is labeled as, “Silt from erosion fills rivers and reservoirs.” The region close to the lake-side is labeled as, “rapid runoff causes flooding.” The text on the top of the agricultural land reads, “Agricultural land is flooded and silted up.” The text beside the grassland where the cattle are grazing reads “Overgrazing accelerates soil erosion by water and wind.” Below that it is labeled as, “winds remove fragile topsoil.” The sand path on the sides of the grassland is labeled as, “Gullies and landslides.”Enlarge Image
This increased runoff of topsoil, combined with heavier-than-normal monsoon rains, has led to more severe flooding along Himalayan rivers, as well as downstream in Bangladesh’s delta areas. In 1998, a disastrous flood covered two-thirds of Bangladesh’s land area, in some places for 2 months, drowning at least 2,000 people and leaving 30 million homeless. It also destroyed more than one-fourth of the country’s crops, which caused thousands of people to die of starvation. Another flood in 2017 affected at least 8 million people by leaving hundreds of thousands homeless and destroying crops and access to clean water.
Many of the coastal mangrove forests in Bangladesh (and elsewhere; see Figure 8.8) have been cleared for fuelwood, farming, and shrimp farming ponds. The result: more severe flooding because these coastal wetlands had helped to shelter Bangladesh’s low-lying coastal areas from storm surges, cyclones, and tsunamis. In areas of Bangladesh still protected by mangrove forests, damages and death tolls from cyclones have been much lower than they were in areas where the forests have been cleared.
Projected rises in sea level and storm intensity during this century, primarily due to projected climate change, will likely be a major threat to Bangladeshis who live on the flat delta adjacent to the Bay of Bengal. This would create millions of environmental refugees with no place to go in this already densely populated country.
Bangladesh is one of the few less-developed nations that is implementing plans to adapt to projected rising sea levels. This includes using varieties of rice and other crops that can better tolerate flooding, saltwater, and drought. People are also building ponds to collect monsoon rainwater and a network of earthen embankments to help protect against high tides and storm surges. Bangladesh has been praised in recent years for its work on disaster preparedness, including construction of storm shelters and improved evacuation procedures. Such measures have resulted in declining death tolls and property damage despite more frequent storms and flooding.
Human activities contribute to flooding in several ways. First, in efforts to reduce the threat of flooding on floodplains, some rivers have been narrowed and straightened, banked by protective dikes and levees (long mounds of earth along their banks), and dammed to create reservoirs that store and release water as needed. However, such measures can lead to greatly increased flood damage when heavy snowmelt or prolonged rains overwhelm dikes and levees.
Second, some human activities include the removal of water-absorbing vegetation, especially on hillsides (Figure 13.27). Once the trees on a hillside have been cut for timber, fuelwood, livestock grazing, or farming, freshwater from precipitation rushes down the naked slopes, eroding precious topsoil. This practice can increase flooding and pollution in local streams. Such deforestation can also make landslides and mudflows more likely.
A third human activity that increases the severity of flooding is the draining of wetlands that naturally absorb floodwaters. These areas often end up covered with pavement and buildings. This leads to greatly increased runoff, which contributes to flooding and pollution of surface water. When Hurricane Katrina struck the Gulf Coast of the United States in August 2005 and flooded the city of New Orleans, Louisiana, the damage was intensified because of the degradation or removal of coastal wetlands. These wetlands had historically helped to absorb water and buffer this low-lying land from storm surges. For this reason, Louisiana officials are now working to restore some coastal wetlands.
A fourth human-related factor likely to increase flooding is a rise in sea levels, projected to occur during this century mostly because of climate change related to human activities. Climate change models project that, by 2075, as many as 150 million people living in the world’s largest coastal cities could be flooded out by rising sea levels.
According to many scientists, we can reduce flooding and water pollution by relying less on engineered devices such as dams and levees and more on nature’s systems. By preserving existing wetlands and restoring degraded wetlands that lie in floodplains, we can take advantage of the natural flood control they provide. These and other ways to reduce our contribution to flooding are listed in
Figure 13.28
.
Figure 13.28
Methods for preventing or reducing the harmful effects of flooding.
Critical Thinking:
Which two of these solutions do you think are the best ones? Why?
An illustration shows information about Reducing Flood Damage in three columns. The text in the first column provides information about Prevention which reads, “Preserve forests in watersheds, preserve and restore wetlands on floodplains, tax development on floodplains, increase use of flood plains for sustainable agriculture and forestry.” The second column shows the photo of a river, flowing along with green vegetation on the sides, and another photo which shows a dam site comprising of the river and dam construction. The third column provides information about Control that reads the text, “Strengthen and deepen streams (channelization), build levees or floodwalls along the streams, and build dams.”
Top: allensima/ Shutterstock.com. Bottom: Zeljko Radojko/ Shutterstock.com.
13.6b
Reducing Flood Risks
Many scientists argue that we could improve flood control by relying less on engineered devices such as dams and levees and more on nature’s systems such as wetlands and forests in watersheds.
One engineering approach is the channelizing of streams, which does reduce upstream flooding. However, it also eliminates the aquatic habitats that lie along a meandering stream by taking the water from those systems and sending it in a faster flow straight down a channel. It also reduces groundwater recharge and often leads to downstream flooding.
Similarly, levees or floodwalls along the banks of a river contain and speed up stream flow and can lead to flooding downstream. They also do not protect against unusually high and powerful floodwaters such as those that occurred in 1993 when water flowed over two-thirds of the levees along the Mississippi River.
Damming, the most common engineering approach, can reduce the threat of flooding by storing water in a reservoir and releasing it gradually. However, dams also have a number of drawbacks (Figure 13.15).
An ecologically oriented approach to reducing flooding is to preserve existing wetlands and restore degraded wetlands that lie in floodplains to take advantage of the natural flood control they provide. We would also be wise to sharply reduce emissions of greenhouse gases that contribute to atmospheric warming and climate change, which will likely raise sea levels and flood many of the world’s coastal areas during this century.
Figure 13.28 summarizes these various ways to reduce flooding risks.
Big Ideas
One of the major global environmental problems is the growing shortage of freshwater in many parts of the world.
We can expand water supplies in water-short areas in a number of ways, but the most important ways are to reduce overall water use and to use water much more efficiently.
We can use water more sustainably by reducing water use, using water more efficiently, cutting water losses, raising water prices, and protecting aquifers, forests, and other ecosystems that store and release water. This chapter’s Core Case Study discusses the problems and tensions that can occur when a large number of U.S. states share a limited river water resource in a water-short region. Such problems are representative of those faced by many other dry regions of the world, especially areas where the population is growing rapidly and water resources are dwindling for various reasons.
Large dams, river diversions, levees, and other big engineering schemes have helped to provide much of the world with electricity, food from irrigated crops, drinking water, and flood control. However, they have also degraded the aquatic natural capital necessary for long-term economic and ecological sustainability by seriously disrupting rivers, streams, wetlands, aquifers, and other aquatic systems.
The three scientific principles of sustainability can guide us in using water more sustainably during this century. Scientists hope to use solar energy to desalinate water and expand freshwater supplies. Recycling more water and reducing water waste will help reduce water losses. Preserving biodiversity by avoiding disruption of aquatic systems and their bordering terrestrial systems is a key factor in maintaining water supplies and water quality. Chapter Review
Doing Environmental Science
1. Investigate water use at your school. Try to determine all specific sources of any water losses, taking careful notes and measurements for each of them, and estimate how much water is lost per hour, per day, and per year from each source. Sum these estimated amounts to arrive at an estimate of total water losses for a year at your school. Develop a water conservation plan for your school and submit it to school officials.
Chapter Review
Ecological Footprint Analysis
The following table is based on data from the Water Footprint Network, a science-based organization that promotes the sustainable use of water through sharing knowledge and building awareness of how water is used. It shows the amounts of virtual water (also called embedded water), or water required to produce each of the products listed in the first column. Study the table and then answer the questions that follow.
Product
Liters per kilogram (kg) or product
Gallons per pound (lb) or product
Beef
15,400/kg
1,855/lb
Pork
5,990/kg
722/lb
Chicken
4,325/kg
521/lb
Milk
255/glass (250 ml)
68/glass (8 oz)
Eggs
196/egg
52/egg
Coffee
132/cup
35/cup
Beer
74/glass (250 ml)
20/glass (8 oz)
Wine
54/glass (250 ml)
14/glass (8 oz)
Apple
125/average size apple
33/apple
Banana
160/large banana
42/banana
Tomato
50/medium tomato
13/tomato
Rice
2,500/kg
301/lb
Bread
1,608/kg
426/lb
Cotton t-shirt
2,495/shirt
661/shirt
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20
th
Edition
Chapter Introduction
·
Core Case Study
The Colorado River
·
13.1
Earth’s Water
Resources
·
13.1a
We Are Managing Freshwater Poorly
·
13.1b
Most of the Earth’s Freshwater Is Not Available to Us
·
13.1c
Groundwater and Surface Water
·
13.1d
Water Use Is Increasing
·
13.1e
Freshwater Shortages Will Grow
·
13.2
Sustainability of Groundwater
·
13.2a
Aquifer Depletion
·
13.2b
Harmful Effects of Overpumping Aquifers
·
13.2c
Tapping Deep Aquifers
·
13.3
Increasing Freshwater Supplies
·
13.3a
Large Dams
·
13.3b
Removing Salt from Seawater to Provide Freshwater
·
13.4
Water Transfers
·
13.4a
Water Transfers Have Benefits and Drawbacks
·
13.5
Using Freshwater More Sustainably
·
13.5a
Cutting Water Waste
·
13.5b
Improving Irrigation Efficiency
·
13.5c
Conserving Water through Low
–
Tech Met
hods
·
13.5d
Cutting Freshwater Waste in Industries and Homes
·
13.5e
Using Less Water to Remove Wastes
·
13.6
Flooding
·
13.6a
Some Areas Get Too M
uch Water
·
13.6b
Reducing Flood Risks
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20
th
Edition
Chapter Introduction
Core Case StudyThe Colorado River
13.1Earth’s Water Resources
13.1aWe Are Managing Freshwater Poorly
13.1bMost of the Earth’s Freshwater Is Not Available to Us
13.1cGroundwater and Surface Water
13.1dWater Use Is Increasing
13.1eFreshwater Shortages Will Grow
13.2Sustainability of Groundwater
13.2aAquifer Depletion
13.2bHarmful Effects of Overpumping Aquifers
13.2cTapping Deep Aquifers
13.3Increasing Freshwater Supplies
13.3aLarge Dams
13.3bRemoving Salt from Seawater to Provide Freshwater
13.4Water Transfers
13.4aWater Transfers Have Benefits and Drawbacks
13.5Using Freshwater More Sustainably
13.5aCutting Water Waste
13.5bImproving Irrigation Efficiency
13.5cConserving Water through Low-Tech Methods
13.5dCutting Freshwater Waste in Industries and Homes
13.5eUsing Less Water to Remove Wastes
13.6Flooding
13.6aSome Areas Get Too Much Water
13.6bReducing Flood Risks
G.
Tyler Miller, Scott E. Spoolman
Living in
th
e Environment
20
th
Edition
·
Chapter Introduction
·
Core
Case Study
The Real Cost of Gold
·
14.1
Geology and Mineral
Resources
·
14.1a
The Earth Is a Dynamic Planet
·
14.1b
Minerals and Rocks
·
14.1c
The Rock Cycle
·
14.1d
Nonrenewable Mineral Resources
·
14.2
Supplies of Nonrenewable Mineral Resources
·
14.2a
Nonrenewable Mineral Resources Can Be Economically Depleted
·
14.2b
Market Prices and Supplies of Mineral Resources
·
14.2c
Mining Lower
–
Grade Ores
·
14.2d
Minerals from the Oceans
·
14.3
Environmental Effects of Using Nonrenewable Mineral Resources
·
14.3a
Harmful Envir
onmental Effects of Extracting Minerals
·
14.3b
Environmental Effects of Removing Metals from Ores
·
14.4
Using Mineral Resources More Sustainably
·
14.4a
Finding Substitutes for Scarce Mineral Resources
·
14.4b
Using Mineral Resources More Sustainably
·
14.5
Geological Hazards
·
14.5a
The Earth Benea
th Your Feet Is Moving
·
14.5b
Volcanic Eruptions
·
14.5c
Earthquakes and Tsunamis
·
Tying It All Together
The Real Cost of Gold and Sustainability
·
Chapter Review
·
Critical Thinking
·
Doing Environmental Science
·
Data Analysis
14.2a
Nonrenewable Mineral Resources Can Be Economically Depleted
Most published estimates of the supply of a given nonrenewable mineral resource refer to its reserves: identified deposits from which we can extract the mineral profitably at current prices. Reserves can be expanded when we find new, profitable deposits or when higher prices or improved mining technologies make it profitable to extract deposits that previously were too expensive to remove.
The future supply of any nonrenewable mineral resource depends on the actual or potential supply of the mineral and the rate at which it is used. Society has never completely run out of a nonrenewable mineral resource. However, a mineral becomes economically depleted when it costs more than it is worth to find, extract, transport, and process the remaining deposits. At that point, there are five choices: recycle or reuse existing supplies, waste less, use less, find a substitute, or do without.
Depletion time is the time it takes to use up a certain proportion—usually 80%—of the reserves of a mineral at a given rate of use. When experts disagree about depletion times, it is often because they are using different assumptions about supplies and rates of use (
Figure 14.4
).
Figure 14.4
Natural capital depletion: Each of these depletion curves for a mineral resource is based on a different set of assumptions. Dashed vertical lines represent the times at which 80% depletion occurs.
A graph with three curves indicating the depletion of mineral resources. The graph is plotted with time on X-axis and the production on Y-axis. Curve A indicates a great increase in production within a very short time period and then falls drastically to zero level within a short time period. The supporting text associated with the curve reads “Mine, use, throw away; no new discoveries; rising prices”. About 80 percent of depletion of the mineral resources is indicated at a time just after the production begins to fall and is labeled “Depletion time A”. Curve B depicts a gradual increase in production with time and similarly the decrease in production is observed gradually with time. The supporting text associated with the curve reads “Recycle, increase reserves by improved mining technology, higher prices and new discoveries”. About 80 percent depletion of the resources is indicated at a time when the production drops to nearly half compared to the peak production and is labeled “Depletion time B”. Curve C depicts a very slow increase in production with time and the drop in production is also very slow. The supporting text associated with the curve reads “Recycle, reuse, reduce consumption; increase reserves by improved mining technology, higher prices and new discoveries”. About 80 percent depletion of resources is indicated at a time when the production drops to about 75 percent compared to the peak and is labeled “Depletion time C”.
The shortest depletion-time estimate assumes no recycling or reuse and no increase in the reserve (curve A, Figure 14.4). A longer depletion-time estimate assumes that recycling will stretch the existing reserve and that better mining technology, higher prices, or new discoveries will increase the reserve (curve B). The longest depletion-time estimate (curve C) makes the same assumptions as those for curve B and assumes that people will reuse and reduce consumption to expand the reserve further. Finding a substitute for a resource leads to a new set of depletion curves for the new mineral.
The earth’s crust contains abundant deposits of nonrenewable mineral resources such as iron and aluminum. However, concentrated deposits of important mineral resources such as manganese, chromium, cobalt, platinum, and rare earth elements (see the Case Study that follows) are relatively scarce. In addition, deposits of many mineral resources are not distributed evenly among countries. Five nations—the United States, Canada, Russia, South Africa, and Australia—supply most of the nonrenewable mineral resources that modern societies use.
Since 1900, and especially since 1950, there has been a sharp rise in the total and per capita use of mineral resources in the United States. According to the USGS, each American directly and indirectly uses an average of 18.4 metric tons (20.3 tons) of mineral resources per year.
The United States has economically depleted some of its once-rich deposits of metals such as lead, aluminum, and iron. In 2018, the United States imported all of its supplies of 21 key nonrenewable mineral resources and for 32 other minerals and relied on imports for more than half of its supplies. Most of these mineral imports come from reliable and politically stable countries. However, there are serious concerns about access to adequate supplies of four strategic metal resources—manganese, cobalt, chromium, and platinum—that are essential for the country’s economic and military strength. The United States has little or no reserves of these metals. China is a major global supplier of crucial minerals such as arsenic to make semiconductors, tungsten found in heating elements and light bulbs, and cadmium used in rechargeable batteries.
Lithium (Li), the world’s lightest metal, is a vital component of lithium-ion batteries, which are used in cell phones, iPads, laptop computers, electric cars, and a growing number of other products. The problem is that some countries, including the United States, do not have large supplies of lithium. Bolivia has about 50% of these reserves, whereas the United States holds only about 3%.
Japan, China, South Korea, and the United Arab Emirates have been buying up access to global lithium reserves to ensure their ability to sell lithium and lithium-ion batteries to the rest of the world. Within a few decades, the United States may be heavily dependent on expensive imports of lithium and lithium-ion batteries. A company is building a plant in California that is designed to extract lithium from brine waste produced by geothermal power plants. If it is successful, this process could lessen some U.S. dependence on imported lithium.
The demand for cobalt, which is widely used in lithium-ion electric-car batteries, magnets, and smartphones has been rising sharply. According to the Bank of America, electric vehicles will account for 34% of all global vehicle sales by 2030, which is expected to triple the global demand for cobalt. In 2019, the three largest producers of cobalt, in order, were the Democratic Republic of Congo (by far the largest producer), Russia, and Cuba. Because China is the world’s largest producer of electric cars and lithium ion batteries, it is buying up access to much of the world’s current and future cobalt production from the Democratic Republic of Congo.
Case Study
The Importance of Rare Earth Metals
Some mineral resources are familiar, such as gold, copper, aluminum, sand, and gravel. Less well known are the rare earth metals and oxides, which are crucial to many technologies that support modern lifestyles and economies.
The 17 rare earth metals, also known as rare earths, include scandium, yttrium, and 15 lanthanide chemical elements, including lanthanum. Because of their superior magnetic strength and other unique properties, these elements and their compounds are important for a number of widely used technologies.
Rare earths are used to make liquid crystal display (LCD) flat screens for computers and television sets, energy-efficient light-emitting diode (LED) light bulbs, solar cells, fiber-optic cables, smart phones, and digital cameras. Rare earths are also part of batteries and motors for electric and hybrid-electric cars (
Figure 14.5
), catalytic converters in car exhaust systems, jet engines, and the powerful magnets in wind turbine generators. Rare earths also go into missile guidance systems, smart bombs, aircraft electronics, and satellites.
Figure 14.5
Manufacturers of all-electric and hybrid-electric cars and other products use a variety of rare earth metals.
An illustration depicting various metals used in the manufacture of electric and hybrid electric cars and other products. An image of car depicting the internal parts of the car has three call outs. A call out pointing to the motor region (represented as a two interconnected drums near the front wheel region) reads, “Electric motors and generator: Dysprosium, Neodymium, Praseodymium, and Terbium.” A call out pointing to the battery (represented as a long yellow rectangle laid flat near the back wheel region) reads, “Battery” Lanthanum, Cerium.” A call out pointing the catalytic converter (represented as small blue rectangle laid flat near the back wheel region) reads, “Catalytic converter: Cerium, Lanthanum”. An image of the windmill (represented as a long pole with three huge blades attached at the tip) reads, “Neodymium.” An image of the camera (represented as a small rectangle with multiple sections and a projection in the front) reads, “Praseodymium.” An image of the monitor (represented as a black rectangle with bright white black center mounted on a small stand) reads, “Europium, Yttrium.”
Without affordable supplies of these metals, industrialized nations could not develop the current versions of cleaner energy technology and other high-tech products that will be major sources of economic growth during this century. Many nations also need these metals to maintain their military strength.
Most rare earth elements are not actually rare, but they are hard to find in concentrations high enough to extract and process at an affordable price. China has the largest share (37%) of the world’s known rare-earth reserves. In 2018, it accounted for 96% of the global mining output of rare-earth metals and in 2019 China gained control of the remaining 4% rare-earth production by acquiring the Molycorp rare-earth mine in Mountain Pass, California. This gives China control over the global price of its rare earth metal exports. China also dominates research and development of rare earth metals. The United States and Japan are heavily dependent on rare earths and their oxides. However, the United States produces no rare earths and has only 1.2% of the global rare-earth reserves. Japan has no rare-earth reserves.
One way to increase supplies of rare earths is to extract and recycle them from the massive amounts of electronic wastes that are being produced. It can also be extracted from large piles of phosphogypsum, a waste product of fertilizer manufacturing. So far, however, less than 1% of rare earth metals are recovered and recycled. Another approach is to find substitutes for rare earth metals. In 2016, Honda produced a hybrid electric car engine with magnets that do not need heavy rare-earth metals and that are 10% cheaper and 8% lighter. 14.2bMarket Prices and Supplies of Mineral Resources
Geological processes determine the quantity and location of a mineral resource in the earth’s crust, but economics determines what part of the known supply is extracted and used. According to standard economic theory, in a competitive market system when a resource becomes scarce, its price rises. Higher prices can encourage exploration for new deposits, stimulate development of better mining technology, and make it profitable to mine lower-grade ores. Higher prices can also promote resource conservation and a search for substitutes.
According to some economists, this price effect may no longer apply completely in most more-developed countries. Governments in such countries often use subsidies, tax breaks, and import tariffs to control the supply, demand, and prices of key mineral resources. In the United States, for instance, mining companies get various types of government subsidies, including depletion allowances—which allow the companies to deduct the costs of developing and extracting mineral resources from their taxable incomes. These allowances amount to 5–22% of their gross income gained from selling the mineral resources.
Connections
High Metal Prices and Thievery
Resource scarcity can promote theft. For example, copper prices have risen sharply in recent years because of increasing demand. As a result, in many U.S. communities, thieves have been stealing copper to sell it. They strip abandoned houses of copper pipe and wiring and steal outdoor central air conditioning units for their copper coils. They also steal wiring from beneath city streets and copper piping from farm irrigation systems. In 2015, thieves stole copper wiring from New York City’s subway system, temporarily shutting down two of the city’s busiest lines.
Generally, the mining industry maintains that they need subsidies and tax breaks to keep the prices of minerals low for consumers. They also claim that, without subsidies and tax breaks, they might move their operations to other countries where they would not have to pay taxes or comply with strict mining and pollution control regulations.
14.2cMining Lower-Grade Ores
Some analysts contend that we can increase supplies of some minerals by extracting them from lower-grade ores. They point to the development of new earth-moving equipment, improved techniques for removing impurities from ores, and other technological advances in mineral extraction and processing that can make lower-grade ores more accessible, sometimes at lower costs. For example, in 1900, the copper ore mined in the United States was typically about 5% copper by weight. Today, it is typically about 0.5%, yet copper costs less (when prices are adjusted for inflation).
Several factors can limit the mining of lower-grade ores. For example, it requires mining and processing larger volumes of ore, which takes much more energy and costs more. Another factor is the dwindling supplies of freshwater needed for the mining and processing of some minerals, especially in dry areas. A third limiting factor is the growing environmental impacts of land disruption, along with waste material and pollution produced during the mining and processing of minerals.
One way to improve mining technology and reduce its environmental impact is to use a biological approach, sometimes called biomining. Miners use naturally occurring or genetically engineered bacteria to remove desired metals from ores through wells bored into the deposits. This leaves the surrounding environment undisturbed and reduces the air and water pollution associated with removing the metal from metal ores. On the downside, biomining is slow. It can take decades to remove the same amount of material that conventional methods can remove within months or years. So far, biomining methods are economically feasible only for low-grade ores for which conventional techniques are too expensive.
14.2dMinerals from the Oceans
Most of the minerals found in seawater occur in such low concentrations that recovering them takes more energy and money than they are worth. Currently, only magnesium, bromine, and sodium chloride are abundant enough to be extracted profitably from seawater. On the other hand, sediments along the shallow continental shelf and adjacent shorelines contain significant deposits of minerals such as sand, gravel, phosphates, copper, iron, silver, titanium, and diamonds.
Another potential ocean source of some minerals is hydrothermal ore deposits that form when superheated, mineral-rich water shoots out of vents in volcanic regions of the ocean floor. As the hot water meets cold seawater, black particles of various metal sulfides precipitate out and accumulate as chimney-like structures, called black smokers, near the hot water vents (
Figure 14.6
). These deposits are especially rich in minerals such as copper, lead, zinc, silver, gold, and some of the rare earth metals. Exotic communities of marine life—including giant clams, six-foot tubeworms, and eyeless shrimp—live in the dark depths around black smokers. Companies from Australia, the United States, and China have been exploring the possibility of mining black smokers in several areas.
Figure 14.6
Natural capital: Hydrothermal deposits, or black smokers, are rich in various minerals.
Because of the rapidly rising prices of many of these metals, interest in deep-sea mining is growing. According to some analysts, seafloor mining is less environmentally harmful than mining on land. Other scientists, however, are concerned sediment stirred up by such mining could harm or kill organisms that feed by filtering seawater. Supporters of seafloor mining say that the number of potential mining sites, and thus the overall environmental impact, will be small.
Another possible source of metals is the potato-size manganese nodules that cover large areas of the Pacific Ocean floor and smaller areas of the Atlantic and Indian Ocean floors. They also contain low concentrations of various rare earth minerals. These modules could be sucked up through vacuum pipes or scooped up by underwater mining machines.
The United Nations International Seabed Authority, established to manage seafloor mining in international waters, began issuing mining permits in 2011. However, mining on the ocean floor has been hindered by the high costs involved, the potential threat to marine ecosystems, and arguments over rights to the minerals in deep ocean areas that do not belong to any specific country.
Learning from Nature
A bacterium that lives in the manganese nodules on the ocean floor is being used to make mining of these nodules less costly. Scientists from India have learned how to employ the bacterium to remove the precious metals from the nodules at room temperature. This could also help to lessen the harmful environmental effects of separating metals from their ores.
14.3aHarmful Environmental Effects of Extracting Minerals
Every metal product has a life cycle that includes mining the mineral, processing it, manufacturing the product, and disposal or recycling of the product (
Figure 14.7
). This process makes use of large amounts of energy and water, and produces pollution and waste at every step of the life cycle.
Figure 14.7
Each metal product that we use has a life cycle.
Left: kaband/ Shutterstock.com. Second to left: Andrey N Bannov/ Shutterstock.com. Center left: Vladimir Melnik/ Shutterstock.com. Center: mares/ Shutterstock.com. Center right: Zhu Difeng/ Shutterstock.com. Second to right: Michael Shake/ Shutterstock.com. Right: Pakhnyushchy/ Shutterstock.com.
The environmental impacts of mining a metal ore are determined partly by the ore’s percentage of metal content, or grade. The more accessible higher-grade ores are usually exploited first. Mining lower-grade ores takes more money, energy, water, and other resources, and leads to more land disruption, mining waste, and pollution.
Several mining techniques are used to remove mineral deposits. Shallow mineral deposits are removed by
surface mining
, in which vegetation, soil, and rock overlying a mineral deposit are cleared away. This waste material is called
overburden
and is usually deposited in piles called
spoils
(
Figure 14.8
). Surface mining is used to extract about 90% of the nonfuel mineral resources and 60% of the coal used in the United States.
Figure 14.8
Natural capital degradation: This spoils pile in Zielitz, Germany, is made up of waste material from the mining of potassium salts used to make fertilizers.
LianeM/ Shutterstock.com
Different types of surface mining can be used, depending on two factors: the resource being sought and the local topography. In
open-pit mining
, machines are used to dig large pits and remove metal ores containing copper, gold (
Core Case Study
), or other metals, or sand, gravel, or stone. The open-pit copper mine shown in the opening photo for this chapter is almost 5 kilometers (3 miles) wide and 1,200 meters (4,000 feet) deep, and is getting deeper.
9 Million
Number of people who could sit in Bingham Copper Mine (see
chapter-opening photo
) if it were a stadium
Strip mining involves extracting mineral deposits that lie in large horizontal beds close to the earth’s surface. In
area strip mining
, used on flat terrain, a gigantic earthmover strips away the overburden, and a power shovel—which can be as tall as a 20-story building—removes a mineral resource such as gold (
Figure 14.9
). The resulting trench is filled with overburden, and a new cut is made parallel to the previous one. This process is repeated over the entire site.
Figure 14.9
Natural capital degradation: Area strip-mining for gold in Yukon Territory, Canada.
Paul Nicklen/National Geographic Image Collection
Contour strip mining
(
Figure 14.10
) is used mostly to mine coal and various mineral resources on hilly or mountainous terrain. Huge power shovels and bulldozers cut a series of terraces into the side of a hill. Then, earthmovers remove the overburden, an excavator or power shovel extracts the coal, and the overburden from each new terrace is dumped onto the one below. Unless the land is restored, this leaves a series of spoils banks and a highly erodible hill of soil and rock called a highwall.
Figure 14.10
Natural capital degradation: Contour strip mining is used in hilly or mountainous terrain.
Another surface mining method is
mountaintop removal
, in which explosives are used to remove the top of a mountain to expose seams of coal that are then extracted (
Figure 14.11
). After a mountaintop is blown apart, enormous machines plow waste rock and dirt into valleys below the mountaintops. This destroys forests, buries mountain streams, and increases the risk of flooding. Wastewater and toxic sludge, produced when the coal is processed, are often stored behind dams in these valleys. Some dams have overflowed or collapsed and released toxic substances such as arsenic and mercury.
Figure 14.11
Natural capital degradation: Mountaintop removal coal mining near Whitesville, West Virginia.
Jim West/Age Fotostock
In the United States, more than 500 mountaintops in West Virginia and other Appalachian states have been removed to extract coal (Figure 14.11). According to the U.S. Environmental Protection Agency (EPA), the resulting spoils have buried more than 1,100 kilometers (700 miles) of streams.
The U.S. Surface Control and Reclamation Act of 1997 requires mining companies to restore mines abandoned before 1977 and companies are required to restore active mines and mines abandoned after 1977. However, the program is greatly underfunded and many mines have not been reclaimed.
Deep deposits of minerals are removed by
subsurface mining
, in which underground mineral resources are removed through tunnels and shafts (
Figure 14.12
). This method is used to remove metal ores and coal that are too deep to be extracted by surface mining. Miners dig a deep, vertical shaft and blast open subsurface tunnels and chambers to reach the deposit. Then they use machinery to remove the resource and transport it to the surface.
Figure 14.12
Subsurface mining of coal.
Subsurface mining disturbs less than one-tenth as much land as surface mining, and usually produces less waste material. However, the environmental damage is significant and can lead to other hazards such as cave-ins, explosions, and fires for miners. Miners often get lung diseases caused by prolonged inhalation of mineral or coal dust in subsurface mines. Another problem is subsidence—the collapse of land above some underground mines. It can damage houses, crack sewer lines, break natural gas mains, and disrupt groundwater systems. Subsurface mining also requires large amounts of water and energy to process and transport the mined material.
Collectively, surface and subsurface mining operations produce three-fourths of all U.S. solid waste and cause major water and air pollution. For example, acid mine drainage occurs when rainwater seeps through an underground mine or a spoils pile from a surface mine. Such water can contain sulfuric acid , produced when aerobic bacteria act on minerals in the spoils. This toxic runoff can pollute nearby streams and groundwater—one of the problems often associated with gold mining (Core Case Study).
According to the EPA, mining has polluted mountain streams in 40% of the western watersheds in the United States. It also accounts for half of all the country’s emissions of toxic chemicals into the atmosphere. In fact, the mining industry produces more of such toxic emissions than any other U.S. industry.
Mining can be even more harmful to the environment in countries where environmental regulations are lacking or not reliably enforced. In China, for instance, the mining and processing of rare earth metals and oxides has stripped land of its vegetation and topsoil. It also has polluted the air, acidified streams, and left toxic and radioactive waste piles.
14.3bEnvironmental Effects of Removing Metals from Ores
Ore extracted by mining typically has two components: the ore mineral that contains the desired metal and waste material. Removing the waste material from ores produces
tailings
—rock wastes that are left in piles or put into ponds where they settle out. Particles of toxic metals in tailings piles can be blown by the wind, washed out by rain, or leak from holding ponds, which can contaminate surface water and groundwater.
After the waste material is removed, heat or chemical solvents are used to extract the metals from mineral ores. Heating ores to release metals is called
smelting
(
Figure 14.7
). Without effective pollution control equipment, a smelter emits large quantities of air pollutants. These pollutants include sulfur dioxide and suspended toxic particles that damage vegetation and acidify soils in the surrounding area. Smelters also cause water pollution and produce liquid and solid hazardous wastes that require safe disposal. A 2012 study found that lead smelting is the world’s second most toxic industry after the recycling of lead-acid batteries.
Using chemicals to extract metals from their ores can also create pollution and health problems, as we saw in the case of using cyanide to remove gold (
Core Case Study
). Millions of poverty-stricken miners in less-developed countries have gone into tropical forests in search of gold. They have cleared trees to get access to gold, and such illegal deforestation has increased rapidly, especially parts of the Amazon Basin and in Africa (
Figure 14.13
). In these small-scale and illegal gold mines, miners use toxic mercury to separate gold from its ore. They heat the mixture of gold and mercury to vaporize the mercury and leave the gold, causing dangerous air and water pollution. They leave behind land stripped of vegetation and topsoil loaded with toxic mercury. Many of the miners and villagers living near the mines eventually inhale toxic mercury vapor, drink mercury-laden water, or eat fish contaminated with mercury.
Figure 14.13
Illegal gold mining on the banks of the Pra River in Ghana, Africa.
Randy Olson/National Geographic Image Collection
14.4aFinding Substitutes for Scarce Mineral Resources
Some analysts believe that even if supplies of key minerals become too expensive or too scarce due to unsustainable use, human ingenuity will find substitutes. They point to the current materials revolution in which silicon and other materials are replacing some metals for common uses. They also point out the possibilities of finding substitutes for scarce minerals through nanotechnology (
Science Focus 14.1
), and other emerging technologies (see
Case Study
that follows).
Science Focus 14.1
The Nanotechnology Revolution
Nanotechnology
uses science and engineering to manipulate and create materials out of atoms and molecules at the ultra-small scale of less than 100 nanometers. The diameter of the period at the end of this sentence is about a half million nanometers.
Currently, nanomaterials are used in more than 1,300 consumer products and the number is growing. Such products include certain batteries, stain-resistant and wrinkle-free clothes, self-cleaning glass surfaces, self-cleaning sinks and toilets, sunscreens, waterproof coatings for cell phones, some cosmetics, some foods, and food containers that release nanosilver ions to kill bacteria, molds, and fungi.
Nanotechnologists envision innovations such as a supercomputer smaller than a grain of rice, thin and flexible solar cell films that could be attached to or painted onto almost any surface, and materials that would make our bones and tendons super strong. Some nanomolecules could be designed to seek out and kill cancer cells or to eliminate the need for allergy shots. Scientists are working on a wearable graphene patch that would help diabetics manage their blood glucose levels without the use of needles. It would measure blood sugar levels in sweat and maintain acceptable levels by delivering a dose of a diabetes drug through the skin without the use of needles. Nanotechnology allows us to make materials from the bottom up, using atoms of abundant elements (primarily hydrogen, oxygen, nitrogen, carbon, silicon, and aluminum) as substitutes for scarcer elements, such as copper, cobalt, and tin.
Nanotechnology has many potential environmental benefits. Designing and building products on the molecular level would greatly reduce the need to mine many materials. It would also require less matter and energy. Nanofilters might someday be used to desalinate and purify seawater at an affordable cost, thereby helping to increase drinking water supplies. GREEN CAREER: Environmental nanotechnology
What is the catch? The main problem is serious concerns about the possible harmful health effects of nanotechnology. Because of their tiny size, nanoparticles are potentially more toxic to humans and other animals than many conventional materials.
Laboratory studies involving mice and other test animals reveal that nanoparticles can be inhaled deeply into the lungs and absorbed into the bloodstream. Nanoparticles can also penetrate cell membranes, including those in the brain, and move across the placenta from a mother to her fetus.
A panel of experts from the U.S. National Academy of Sciences has said that the U.S. government is not doing enough to evaluate the potential health and environmental risks of using nanomaterials. For example, the U.S. Food and Drug Administration does not maintain a list of the food products and cosmetics that contain nanomaterials. By contrast, the European Union takes a precautionary approach to the use of nanomaterials, requiring manufacturers to demonstrate the safety of their products before they can enter the marketplace. Many analysts call for greatly increased research on the potential harmful health effects of nanoparticles and for labeling all products that contain nanoparticles.
Critical Thinking
1. Do you think the potential benefits of nanotechnology products outweigh their potentially harmful effects? Explain.
Case Study
Graphene and Phosphorene: New Revolutionary Materials
Graphene is made from graphite—a form of carbon that occurs as a mineral in some rocks. Ultrathin graphene consists of a single layer of carbon atoms packed into a two-dimensional hexagonal lattice (somewhat like chicken wire) that can be applied as a transparent film to surfaces (
Figure 14.14
).
Figure 14.14
Graphene, which consists of a single layer of carbon atoms linked together in a hexagonal lattice, is a revolutionary new material.
Vincenzo Lombardo/Photographer’s Choice/Getty Images
Graphene is one of the world’s thinnest and strongest materials and is light, flexible, and stretchable. A single layer of graphene is 150,000 times thinner than a human hair and 100 times stronger than structural steel. A sheet of this amazing material stretched over a coffee mug could support the weight of a car. It is also a better conductor of electricity than copper and conducts heat better than any known material.
The use of graphene could revolutionize the electric car industry by leading to the production of batteries that can be recharged 10 times faster and hold 10 times more power than current car batteries. Graphene composites can also be used to make stronger and lighter plastics, lightweight aircraft and motor vehicles, flexible computer tablets, and TV screens as thin as a magazine. It might also be used to make flexible, more efficient, less costly solar cells that can be attached to almost anything. In addition, engineers hope to make advances in desalination by using graphene to make the membrane used in reverse osmosis (see
Figure 13.17
, left).
Researchers are looking into possible harmful effects of graphene production and use. A study led by Sharon Walker at the University of California–Riverside found graphene oxide in lakes and drinking water storage tanks. This could increase the chances that animals and humans could ingest the chemical, which was found in some early studies to be toxic to mice and human lung cells.
Graphene is made from very high purity and expensive graphite. According to the USGS, China controls about two-thirds of the world’s high-purity graphite production. The United States mines very little natural graphite and imports most of its graphite from Mexico and China, which could restrict U.S. product exports as the use of graphene grows.
Geologists are looking for deposits of graphite in the United States. However, a team of Rice University chemists, led by James M. Tour, found ways to make large sheets of high-quality graphene from inexpensive materials found in garbage and from dog feces. If such a process becomes economically feasible, this could reduce concern over supplies of graphite, along with any harmful environmental effects of the mining and processing of graphite.
In 2014, a team of researchers at Purdue University was able to isolate a single layer of black phosphorus atoms—a new material known as phosphorene. As a semiconductor, it is more efficient than silicon transistors that are used as chips in computers and other electronic devices. Replacing them with phosphorene transistors could make almost any electronic device run much faster while using less power. This could revolutionize computer technology. However, phosphorene must be sealed in a protective coating because it breaks down when exposed to air.
For example, fiber-optic glass cables that transmit pulses of light are replacing copper and aluminum wires in telephone cables, and nanowires may eventually replace fiber-optic glass cables. High-strength plastics and materials, strengthened by lightweight carbon, hemp, and glass fibers, are beginning to transform the automobile and aerospace industries. These new materials do not need painting (which reduces pollution and costs) and can be molded into any shape. Use of such materials in manufacturing motor vehicles and airplanes could greatly increase vehicle fuel efficiency by reducing vehicle weights.
Learning from Nature
Without using toxic chemicals, spiders rapidly build their webs by producing threads of silk strong enough to capture insects flying at high speeds. Learning how spiders do this could revolutionize the production of high-strength fibers with a very low environmental impact.
We can also find substitutes for rare earths. For example, electric car battery makers are beginning to switch from making nickel-metal-hydride batteries, which require the rare earth metal lanthanum, to manufacturing lighter-weight lithium-ion batteries, which researchers are trying to improve (
Individuals Matter 14.1
).
Individuals Matter 14.1
Yu-Guo Guo: Designer of Nanotechnology Batteries and National Geographic Explorer
© Jinsong Hu
Yu-Guo Guo is a professor of chemistry and a nanotechnology researcher at the Chinese Academy of Sciences in Beijing. He has invented nanomaterials that can be used to make lithium-ion battery packs smaller, more powerful, and less costly, which makes them more useful for powering electric cars and electric bicycles. This is an important scientific advance, because the battery pack is the most important and expensive part of any electric vehicle.
Guo’s innovative use of nanomaterials has greatly increased the power of lithium-ion batteries by enabling electric current to flow more efficiently through what he calls “3-D conducting nanonetworks.” With this promising technology, lithium-ion battery packs in electric vehicles can be fully charged in a few minutes, as quickly as filling a car with gas. They also have twice the energy storage capacity of today’s batteries, and thus will extend the range of electric vehicles by enabling them to run longer. Guo is also interested in developing nanomaterials for use in solar cells and fuel cells that could be used to generate electricity and to power vehicles.
Despite its potential, resource substitution is not a cure-all. Finding acceptable and affordable substitutes for some resources may not always be possible.
14.4bUsing Mineral Resources More Sustainably
Figure 14.15
lists several ways to use mineral resources more sustainably. One strategy is to focus on recycling and reuse of nonrenewable mineral resources, especially valuable or scarce metals such as gold (
Core Case Study
), iron, copper, aluminum, and platinum. Recycling, an application of the chemical cycling principle of sustainability, has a much lower environmental impact than that of mining and processing metals from ores.
Figure 14.15
Ways to use nonrenewable mineral resources more sustainably.
Critical Thinking:
1. Which two of these solutions do you think are the most important? Why?
For example, recycling aluminum beverage cans and scrap aluminum produces 95% less air pollution and 97% less water pollution, and uses 95% less energy, than mining and processing aluminum ore. We can also extract and recycle valuable gold (
Core Case Study
) from discarded cell phones. Cleaning up and reusing items instead of breaking them down and recycling them has an even lower environmental impact.
Using mineral resources more sustainably is a major challenge in the face of rising demand for many minerals. For example, one way to increase supplies of rare earths is to extract and recycle them from the massive amounts of electronic wastes that are being produced. So far, however, less than 1% of rare earth metals are recovered and recycled.
Another way to use minerals more sustainably is to find substitutes for rare minerals, ideally, substitutes without serious environmental impacts. For example, electric car battery makers are beginning to switch from making nickel-metal-hydride batteries, which require the rare earth metal lanthanum, to manufacturing lighter-weight lithium-ion batteries, which researchers are now trying to improve (
Individuals Matter 14.1
).
Scientists are also searching for substitutes for rare earth metals that are used to make increasingly important powerful magnets and related devices. In Japan and the United States, researchers are developing a variety of such devices that require no rare earth minerals, are light and compact, and can deliver more power with greater efficiency at a reduced cost.
14.5aThe Earth Beneath Your Feet Is Moving
We tend to think of the earth’s crust as solid and unmoving. However, the flows of energy and heated material within the earth’s convection cells (
Figure 14.2
) are so powerful that they have caused the lithosphere to break up into seven major rigid plates and many minor plates, all called
tectonic plates
, which move extremely slowly atop the asthenosphere (
Figure 14.16
).
Figure 14.16
The earth’s crust has been fractured into 7 major and many minor tectonic plates. White arrows and the bottom of the figure show where plates are sliding past one another at transform faults, colliding at convergent plate boundaries, or moving away from one another at divergent plate boundaries.
Question:
1. Which plate are you riding on?
Tectonic plates are somewhat like the world’s largest and slowest-moving surfboards on which we ride without noticing their movement. Their typical speed is about the rate at which your fingernails grow. Throughout the earth’s history, landmasses have split apart and joined as tectonic plates shifted around, changing the size, shape, and location of the earth’s continents (
Figure 4.B
). This slow movement of the continents across the earth’s surface is called
continental drift
.
Much of the geological activity at the earth’s surface takes place at the boundaries between tectonic plates as they slide past one-another at a transform fault, move toward one another at a convergent plate boundary, or move away from one another at a divergent plate boundary (Figure 14.16, bottom). The tremendous forces produced at these boundaries can form mountains and deep crevices and cause earthquakes and volcanic eruptions.
The boundary that occurs where two plates move away from each other is called a
divergent plate boundary
(
Figure 14.17
). At such boundaries, magma flows up where the plates separate, sometimes hardening and forming new crust and sometimes breaking to the surface and causing volcanic eruptions. Earthquakes can also occur because of divergence of plates, and superheated water can erupt as geysers.
Figure 14.17
The North American Plate and the Pacific Plate slide very slowly against each other in opposite directions along the San Andreas fault (see photo), which runs almost the full length of California (see map). It has been the site of many earthquakes of varying magnitudes.
Kevin Schafer/Age Fotostock
Another type of boundary is the
convergent plate boundary
(Figure 14.16), where two tectonic plates are colliding. This super-slow-motion collision causes one or both plate edges to buckle and rise, forming mountain ranges. In most cases, one plate slides beneath the other, melting and making new magma that can rise through cracks and form volcanoes near the boundary. The overriding plate is pushed up and made into mountainous terrain.
The third major type of boundary is the
transform fault
, or
transform plate boundary
(Figure 14.16), where two plates grind along in opposite directions next to each other. The tremendous forces produced at these boundaries can form mountains or deep cracks and cause earthquakes and volcanic eruptions.
14.5bVolcanic Eruptions
A
volcano
is an opening in the earth’s crust through which magma, gases, and ash are ejected explosively or from which lava flows. An active volcano occurs where magma rising in a plume through the lithosphere reaches the earth’s surface through a central vent or a long crack, called a fissure (
Figure 14.18
). Magma or molten rock that reaches the earth’s surface is called lava.
Figure 14.18
Sometimes, the internal pressure in a volcano is high enough to cause lava, ash, and gases to be ejected into the atmosphere (photo inset) or to flow over land, causing considerable damage.
beboy/ Shutterstock.com
Many volcanoes form along the boundaries of the earth’s tectonic plates when one plate slides under or moves away from another plate (
Figure 14.15, bottom). A volcanic eruption releases chunks of lava rock, liquid lava, glowing hot ash, and gases (including water vapor, carbon dioxide, and sulfur dioxide). Eruptions can be explosive and extremely destructive, causing loss of life and obliterating ecosystems and human communities. They can also be slow and much less destructive with lava gurgling up and spreading slowly across the land or sea floor.
While volcanic eruptions can be destructive, they can also form majestic mountain ranges and lakes, and the weathering of lava contributes to fertile soils. Hundreds of volcanoes have erupted on the ocean floor, building cones that have reached the ocean’s surface, eventually to form islands that have become suitable for human settlement, such as the Hawaiian Islands.
We can reduce the loss of human life and some of the property damage caused by volcanic eruptions by using historical records and geological measurements to identify high-risk areas, so that people can avoid living in those areas. Scientists and engineers are also developing monitoring devices that warn us when volcanoes are likely to erupt.
Connections
Plate Tectonics and the Carbon Cycle
Without plate tectonics, the earth would not have life as we know it. The continual movement of the tectonic plates and resulting volcanoes move carbon from the lithosphere to the hydrosphere and atmosphere and back again, thus playing a key role in the carbon cycle on which life depends.
14.5cEarthquakes and Tsunamis
Forces inside the earth’s mantle put tremendous stress on rock within the crust. Such stresses can be great enough to cause sudden breakage and shifting of the rock, producing a fault, or fracture in the earth’s crust (
Figure 14.17). When a fault forms, or when there is abrupt movement on an existing fault, energy that has accumulated over time is released in the form of vibrations, called seismic waves, which move in all directions through the surrounding rock—an event called an
earthquake
(
Figure 14.19
). Most earthquakes occur at the boundaries of tectonic plates (
Figures 14.16
).
Figure 14.19
An earthquake (left) is one of nature’s most powerful events. The photo shows damage from a 2010 earthquake in Port-au-Prince, Haiti.
AP Images/Jorge Cruz
Seismic waves move upward and outward from the earthquake’s focus like ripples in a pool of water. Scientists measure the severity of an earthquake by the magnitude of its seismic waves. The magnitude is a measure of ground motion (shaking) caused by the earthquake, as indicated by the amplitude, or size of the seismic waves when they reach a recording instrument, called a seismograph.
Scientists use the Richter scale, on which each unit has an amplitude 10 times greater than the next smaller unit. Seismologists, or people who study earthquakes, rate earthquakes as insignificant (less than 4.0 on the Richter scale), minor (4.0–4.9), damaging (5.0–5.9), destructive (6.0–6.9), major (7.0–7.9), and great (over 8.0). The largest recorded earthquake occurred in Chile on May 22, 1960, and measured 9.5 on the Richter scale. Each year, scientists record the magnitudes of more than 1 million earthquakes, most of which are too small to feel.
The primary effects of earthquakes include shaking and sometimes a permanent vertical or horizontal displacement of a part of the crust. These effects can have serious consequences for people and for buildings, bridges, freeway overpasses, dams, and pipelines.
One way to reduce the loss of life and property damage from earthquakes is to examine historical records and make geological measurements to locate active fault zones. We can then map high-risk areas (
Figure 14.20
) and establish building codes that regulate the placement and design of buildings in such areas. Then people can evaluate the risk and factor it into their decisions about where to live. In addition, engineers know how to make homes, large buildings, bridges, and freeways more earthquake resistant, although this is costly.
Figure 14.20
Comparison of degrees of earthquake risk across the continental United States.
Question:
1. What is the earthquake risk where you live or go to school?
Learning from Nature
Because a spider can squeeze through tight spaces and quickly change directions, German researchers used the spider as a model for a new robot that can probe hazardous disaster sites where people cannot safely go, looking for survivors or sending out data to help deal with the disaster. It could be reproduced inexpensively on a 3D printer to be made available for all sorts of natural and industrial catastrophes.
A
tsunami
is a series of large waves generated when part of the ocean floor suddenly rises or drops (
Figure 14.21
). Most large tsunamis are caused when certain types of faults in the ocean floor move up or down because of a large underwater earthquake. Other causes are landslides generated by earthquakes and volcanic eruptions.
Figure 14.21
Formation of a tsunami. The map shows the area affected by a large tsunami in December 2004—one of the largest ever recorded.
Left: Science Source. Right: Science Source.
Tsunamis are often called tidal waves, although they have nothing to do with tides. They can travel across the ocean at the speed of a jet plane. In deep water, the waves are very far apart—sometimes hundreds of kilometers—and their crests are not very high. As a tsunami approaches a coast with its shallower waters, it slows down, its wave crests squeeze closer together, and their heights grow rapidly. It can hit a coast as a series of towering walls of water that can level buildings.
The largest recorded loss of life from a tsunami occurred in December 2004 when a great underwater earthquake in the Indian Ocean with a magnitude of 9.2 caused a tsunami that killed more than 230,000 people and devastated many coastal areas of Indonesia (
Figure 14.22
and map in Figure 14.21), Thailand, Sri Lanka, South India, and eastern Africa. It displaced about 1.7 million people (1.3 million of them in India and Indonesia), and destroyed or damaged about 470,000 buildings and houses. There were no recording devices in place to provide an early warning of this tsunami.
Figure 14.22
The Banda Aceh Shore near Gleebruk, Indonesia on June 23, 2004 (left), and on December 28, 2004 (right), after it was struck by a tsunami.
New York Public Library/Science Source
In 2011, a large tsunami caused by a powerful earthquake off the coast of Japan generated 3-story high waves that killed almost 19,000 people, displaced more than 300,000 people, and destroyed or damaged 125,000 buildings. It also heavily damaged three nuclear reactors, which then released dangerous radioactivity into the surrounding environment.
In some areas, scientists have built networks of ocean buoys and pressure recorders on the ocean floor to collect data that can be relayed to tsunami emergency warning centers. However, these networks are far from complete.
Big Ideas
· Dynamic forces that move matter within the earth and on its surface recycle the earth’s rocks, form deposits of mineral resources, and cause volcanic eruptions, earthquakes, and tsunamis.
· The available supply of a mineral resource depends on how much of it is in the earth’s crust, how fast we use it, the mining technology used to obtain it, its market prices, and the harmful environmental effects of removing and using it.
· We can use mineral resources more sustainably by trying to find substitutes for scarce resources, reducing resource waste, and reusing and recycling nonrenewable minerals.
· Tying It All TogetherThe Real Cost of Gold and Sustainability
·
·
Matt Benoit/ Shutterstock.com
· In this chapter’s
Core Case Study, we considered the harmful effects of gold mining as an example of the impacts of our extraction and use of mineral resources. We saw that these effects make gold much more costly, in terms of environmental and human health costs, than is reflected in the price of gold.
· In this chapter, we looked at technological developments that could help us to expand supplies of mineral resources and to use them more sustainably. For example, if we develop it safely, we could use nanotechnology to make new materials that could replace scarce mineral resources and greatly reduce the environmental impacts of mining and processing such resources. For example, we might use graphene to produce more efficient and affordable solar cells to generate electricity—an application of the solar energy principle of sustainability. We can also use mineral resources more sustainably by reusing and recycling them, and by reducing unnecessary resource use and waste—applying the chemical cycling principle of sustainability. In addition, industries can mimic nature by using a diversity of ways to reduce the harmful environmental impacts of mining and processing mineral resources, thus applying the biodiversity principle of sustainability.
Chapter Review
Critical Thinking
1. Do you think that the benefits we get from gold—its uses in jewelry, dentistry, electronics, and other uses—are worth the real cost of gold (Core Case Study)? If so, explain your reasoning. If not, explain your argument for cutting back on or putting a stop to the mining of gold.
2. You are an igneous rock. Describe what you experience as you move through the rock cycle. Repeat this exercise, assuming you are a sedimentary rock and again assuming you are a metamorphic rock.
3. What are three ways in which you benefit from the rock cycle?
4. Suppose your country’s supply of rare earth metals was cut off tomorrow. How would this affect your life? Give at least three examples. How would you adjust to these changes? Explain.
5. Use the second law of thermodynamics (see
Chapter 2
) to analyze the scientific and economic feasibility of each of the following processes:
1. Extracting certain minerals from seawater
2. Mining increasingly lower-grade deposits of minerals
3. Continuing to mine, use, and recycle minerals at increasing rates.
6. Suppose you were told that mining deep-ocean mineral resources would mean severely degrading ocean bottom habitats and life forms such as giant tubeworms and giant clams (Figure 14.6). Do you think that such information should be used to prevent ocean bottom mining? Explain.
7. List three ways in which a nanotechnology revolution could benefit you and three ways in which it could harm you. Do you think the benefits outweigh the harms? Explain.
8. What are three ways to reduce the harmful environmental impacts of the mining and processing of nonrenewable mineral resources? What are three aspects of your lifestyle that contribute to these harmful impacts?
Chapter Review
Doing Environmental Science
Do research to determine which mineral resources go into the manufacture of each of the following items and how much of each of these resources are required to make each item:
1. a cell phone,
2. a wide-screen TV, and
3. a large pickup truck.
Pick three of the lesser-known mineral materials that you have learned about in this exercise and do more research to find out where in the world most of the reserves for that mineral are located. For each of the three minerals you chose, try to find out what kinds of environmental effects have resulted from the mining of the mineral in at least one of the places where it is mined. You might also find out about steps that have been taken to deal with those effects. Write a report summarizing all of your findings.
Chapter Review
Data Analysis
Rare earth metals are widely used in a variety of important products (see
Case Study
, this chapter). According to the U.S. Geological Survey, China has about 37% of the world’s reserves of rare earth metals. Use this information to answer the following questions.
1. In 2017, China had 44 million metric tons of rare earth metals in its reserves and produced 105,000 metric tons of these metals. At this rate of production, how long will China’s rare earth reserves last?
2. In 2017, the global demand for rare earth metals was about 130,000 metric tons. At this annual rate of use, if China were to produce all of the world’s rare earth metals, how long would their reserves last?
3. The annual global demand for rare earth metals is projected to rise to at least 180,000 metric tons by 2020. At this rate, if China were to produce all of the world’s rare earth metals, how long would its reserves last?
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20
th
Edition
·
Chapter Introduction
·
Core Case Study
The Real Cost of Gold
·
14.1
Geology and Mineral
Resources
·
14.1a
The Earth Is a Dynamic Planet
·
14.1b
Minerals and Rocks
·
14.1c
The Rock Cycle
·
14.1d
Nonrenewable Mineral Resources
·
14.2
Supplies of Nonrenewable Mineral Resources
·
14.2a
Nonrenewable Mineral Resources Can Be Economically Depleted
·
14.2b
Market Prices and Supplies of Mineral Resources
·
14.2c
Mining Lower
–
Grade Ores
·
14.2d
Minerals from the Oceans
·
14.3
Environmental Effects of Using Nonrenewable Mineral Resources
·
14.3a
Harmful Envir
onmental Effects of Extracting Minerals
·
14.3b
Environmental Effects of Removing Metals from Ores
·
14.4
Using Mineral Resources More Sustainably
·
14.4a
Finding Substitutes for Scarce Mineral Resources
·
14.4b
Using Mineral Resources More Sustainably
·
14.5
Geological Hazards
·
14.5a
The Earth Benea
th Your Feet Is Moving
·
14.5b
Volcanic Eruptions
·
14.5c
Earthquakes and Tsunamis
·
Tying It All Together
The Real Cost of Gold and Sustainability
·
Chapter Review
·
Critical Thinking
·
Doing Environmental Science
·
Data Analysis
G. Tyler Miller, Scott E. Spoolman
Living in the Environment
20
th
Edition
Chapter Introduction
Core Case StudyThe Real Cost of Gold
14.1Geology and Mineral Resources
14.1aThe Earth Is a Dynamic Planet
14.1bMinerals and Rocks
14.1cThe Rock Cycle
14.1dNonrenewable Mineral Resources
14.2Supplies of Nonrenewable Mineral Resources
14.2aNonrenewable Mineral Resources Can Be Economically Depleted
14.2bMarket Prices and Supplies of Mineral Resources
14.2cMining Lower-Grade Ores
14.2dMinerals from the Oceans
14.3Environmental Effects of Using Nonrenewable Mineral Resources
14.3aHarmful Environmental Effects of Extracting Minerals
14.3bEnvironmental Effects of Removing Metals from Ores
14.4Using Mineral Resources More Sustainably
14.4aFinding Substitutes for Scarce Mineral Resources
14.4bUsing Mineral Resources More Sustainably
14.5Geological Hazards
14.5aThe Earth Beneath Your Feet Is Moving
14.5bVolcanic Eruptions
14.5cEarthquakes and Tsunamis
Tying It All TogetherThe Real Cost of Gold and Sustainability
Chapter Review
Critical Thinking
Doing Environmental Science
Data Analysis
ENV330 Module 4 AVP Transcript
Title Slide
Narrator: In Module 4, we will consider the impact of food production and distribution and sustainable
food production. The total amount of food grown and produced for humans has increased dramatically
over the past 50 years to meet the growing demands of our human population. Agricultural production,
meat production and fish catch, both wild caught and aquaculture have all increased dramatically. The
world’s three largest grain-producing countries are China, the United States, and India.
What kinds of stresses has this placed on the natural capital and ecosystems of the world?
Slide 2
Title: Impacts of Food Production
Slide content:
[image of a desert]
Narrator: The impacts include loss of biodiversity, soil degradation, wasting and pollution of scarce water
resources, increased greenhouse gas emissions, depletion of fish stocks in the oceans, and human
health problems. According to a 2002 study by the United Nations, nearly 30% of the world’s cropland
has been degraded to some degree by soil erosion, salt buildup, and chemical pollution, and 17% has
been seriously degraded.
There are serious soil erosion problems on every continent of the world, and marine biologists say that
we’ve “fished out” much of the oceans.
Slide 3
Title: Dust Bowl in 1930’s
Slide Content:
[black and white image of a dust cloud taking over a town]
Narrator: Overgrazing, poor agricultural practices including salinization from irrigation can cause erosion,
desertification and dust storms. Deforestation of hillsides can also impact agriculture and ecosystems.
Once a hillside has been deforested for timber, fuelwood, livestock grazing, or unsustainable farming,
water from precipitation rushes down the denuded slopes, erodes precious topsoil, and can increase
flooding and pollution in local streams. Such deforestation can also increase landslides and mudflows. A
3,000-year-old Chinese proverb says, “To protect your rivers, protect your mountains.”
Waste of water is one of the major environmental problems associated with agriculture. The most
efficient (90-95%) way to get water to the roots of crops is through drip irrigation, or Low Energy Precision
Application (LEPA), which you will learn about in this module.
During the Dust Bowl in the US in the 1930’s, terribly unsustainable agricultural practices in the Midwest
breadbasket led to such dire conditions that millions of starving people migrated away from the farmlands.
Many children died from inhaling the dust. The situation got so bad that during a Senate hearing on the
issue in DC, dust from a dust storm leaked into the conference room!
A few inches of top soil is all that keeps civilization from starvation – we need to protect this vital natural
capital.
Slide 4
Title: Industrialized Agriculture
Slide Content:
[image of farm equipment on an empty field]
Narrator: Industrialized agriculture uses about 17% of all commercial energy used in the US. 5% is for
used for transporting food the average 1300 miles from farm to plate in the US. The resulting pollution
degrades the air and water.
What effects do you think industrialized agriculture has on Global Climate Change?
As Rajendra Pachauri, head of the UN Intergovernmental Panel on Climate Change puts it, “We need to
start eating as if Earth’s climate mattered.”
Chemical pesticides used in industrial agriculture are another issue with grave ecological and
environmental effects. Farmers use many tons of them on every crop leading to genetic resistance by
insects and other agricultural pests, pollution of steams and poisoning of wildlife, contamination of food,
and they kill natural pests’ enemies.
Organic farming avoids these problems.
Additionally, there are many ways to protect soil and minimize erosion, including: terracing, contour
plowing, strip cropping, alley cropping, and windbreaks.
You will learn about these and other sustainable farming techniques in this module.
Slide 5
Title: Factory Meat Farming
Slide Content:
[image of pigs in a barn]
Narrator: The US grows and kills nearly 10 billion animals a year despite making up only 4.5% of the
world’s population. The use of animal feedlots has increased dramatically during the last few decades.
In addition to the ethical issues related to animal cruelty in horrendously crowded conditions, many
serious environmental problems are caused by feedlots and factory meat farming. For example, the
concentrated poultry and hog houses produce as much sewage as cities, leading to eutrophication
problems in streams, rivers and coastal areas when the nutrients enter those waters. The excess
nutrients stimulate rapid algal growth, called an algal “bloom”. The water becomes cloudy and blocks the
light leading to massive die-off of the algae. Microbial decomposition uses up most of the dissolved O2 ,
leading to massive “dead zones” in which fish and other animals suffocate.
Meat production also requires much more energy than growing grain. Due again to the 2
nd
Law of
Energy, and the energy pyramid, up to 90% of the energy in grain fed to animals is converted into low
quality waste heat energy. Therefore, it takes 7 lbs. of grain to create 1 lb. of beef, and 4 lbs. of grain to
produce 1 lb. of pork. The efficiency of producing chicken and fish is much higher – a 45% and 50%
conversion of grain energy to meat energy. Of course, a vegetarian diet eliminates all of this lost food
energy.
Aquaculture, the raising of seafood in large enclosures, offers some advantages but also has
disadvantages. You will learn about aquaculture in this module.
QUESTION: Why do most people in poor overpopulated societies subsist mainly on a vegetarian diet?
Yes, it’s much more efficient to feed the crops directly to people and thereby eliminate the inefficient
conversion of plants to meat with up to 90% conversion of plant energy to waste heat energy due to the
2
nd
Law of Energy. You can feed 10-20 times as many people from the same amount of land if you
eliminate the livestock.
ANOTHER QUESTION: Who will eat meat when the human population of the Earth doubles again to 12
or 13 billion?
Answer: Perhaps no one!! It could become a distant memory only remembered in tales told by old
grandfathers.
ETHICAL QUESTION: Is it ethical to eat meat on an overcrowded planet where thousands of children die
from malnutrition each day?
I’m going to let you ponder those questions. And while you are pondering, we can all help by wasting
less food, eating less or no meat, using organic farming to grow some of our own food, buying organic
food, eating locally grown food, and composting .
To create sustainable agriculture we need to mimic nature.
End of Presentation
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