The quiz have 30 question and it will take 80 minute. Most are multiple choice question. I attached the study guide and sample in the field.
ESS 1: Study Guide for Exam 4 2020
Your primary sources of information are the lecture videos and questions, weekly quizzes, and
discussion worksheets with the textbook used only for additional background on an optional
basis. If a term or topic is in the textbook but we did not mention it at all in the lectures then
you will not need to know it for the midterm.
Below is a list of the important topics we have covered – concentrate on understanding and
applying your new knowledge rather than memorizing. I will give you formulae and I will not ask
you to write out definitions (although they may come up in multiple choice questions). You also
do not need to memorize things such as exact amount of warming that has occurred.
We will be using Respondus Lockdown Browser and Monitor to proctor the exam online – you
will therefore need a working webcam and microphone. The exam will consist of a mixture of
short answer and multiple choice questions within Canvas Quizzes. During the exam you can use
as many paper notes as you like but you will not be allowed to use calculators, any other
electronic devices, and you are not allowed to communicate with anyone else.
Some topics from Exams 1, 2, and 3 which I would expect you to be aware of:
– What are the 4 major reservoirs
– Be able to identify/explain/analyse positive and negative feedbacks
– Be able to identify reservoirs, sources, sinks, and calculate residence times
– That plate tectonics has resulted in the occurrence and positions of our continents,
mountain ranges, and ocean basins (i.e. it created land-sea contrasts, mountain ranges
etc.)
– Weathering – chemical (definition, example) and physical (definition, examples)
– Temperature patterns on Earth: Be able to:
o explain why the poles are colder than the Equator
o explain how the mechanics of Earth’s orbit causes seasons
– Be able to describe and explain the 5 factors that control Earth’s energy balance and
surface temperature
o Sun’s luminosity
o Distance from Sun
o Earth’s atmosphere and albedo
o Earth’s temperature (stabilizing blackbody feedback)
o Greenhouse Effect
– Be able to explain/predict how these factors change on different timescales on Earth
and be able to apply the same ideas to other terrestrial planets
– Be aware of the reservoirs and fluxes that make up the hydrologic cycle
– Understand that our oceans are under threat from human activities. Be able to explain
how humans are affecting life in the oceans by:
o Overfishing
o Pollution by fertilizers
o Ocean acidification (due to rising CO2 levels in the atmosphere)
– Be able to explain possible sources of freshwater, the consequences of overusing these
sources, and how climate change will affect their availability
– Be able to explain how ice and snow are being affected by climate change, and in turn
the feedbacks related to ice and permafrost
From Lecture 19 – The Biosphere
– Essential properties of living organisms (metabolism, growth, reproduction, evolution)
– Be able to explain the differences between prokaryotes and eukaryotes
– Be able to explain the differences between autotrophs and heterotrophs and identify
them on a foodweb
– Be able to write/identify the chemical equations for photosynthesis and respiration
– Be able to interpret/draw simple foodchains/foodwebs, identify different trophic levels
and be able to identify primary producers, primary consumers, etc
– Be able to explain why energy is not recycled through an ecosystem and why there are
fewer organisms/less biomass at higher trophic levels
– Be able to explain what is meant by biomass and net primary production
– Be able to explain the global distribution of net primary productivity across Earth and
what limits net primary productivity
– Be able to explain the factors that control the distribution of different biomes across
Earth
– Distribution of life
o Understand and be able to explain/identify how populations change through
time and why e.g. exponential growth, carrying capacity
o Be able to predict/explain how competition of species and availability of
ecological niches affect biodiversity
o Be able to predict/explain how the physical environment may limit biodiversity,
populations of organisms, and the distribution of biomes
From Lecture 20 – Biodiversity and evolution
– Biodiversity
o Be able to explain or identify whether a change in a population of organisms is
an evolutionary change or not
o Be able to identify whether a given change is a mutation, genetic drift, or
natural selection
o Be able to explain the pattern of biodiversity across the Earth
o Be able to describe/explain/identify processes that create and destroy
biodiversity
– Be aware of the theories of where life might have begun
– Be able to explain how the biosphere affected atmospheric oxygen levels and how
atmospheric oxygen levels in turn allowed the evolution of more complex life
– Be aware of some of the major events in evolution of life and a rough idea of when
these events occurred in relation to each other and in relation to the age of the Earth (I
won’t ask you for exact dates or the names of the periods e.g. Hadean)
From Lecture 21 – Are we living through the 6th mass extinction?
– Be able to describe some causes of mass extinctions
– Be able to explain the causes of current loss of biodiversity and characteristics of species
that are vulnerable to extinction (you are not expected to know the specific % of species
lost etc)
– Be able to describe/explain/identify/give examples of the different “ecosystem services”
that life on Earth provides to humans
– Be able to give examples of how the Earth system influences the biosphere
– Be able to give examples of how the biosphere influences the Earth system
From Lecture 22 – Biogeochemical cycles
– Be able to identify the “big 6” elements needed for life
– Be able to describe the range of strategies life uses to obtain necessary elements
– Be able to explain/identify the processes of bioconcentration, bioaccumulation,
biomagnification and some of the consequences of these
– For each of the phosphorus, nitrogen, and carbon cycles:
o Be able to identify reservoirs and fluxes from a diagram
o Be able to calculate residence times
o Be able to explain the importance of the element for the earth system and for
people
o Be able to describe and explain how humans are affecting the cycling of the
element
Lecture 23 – Human population and resource demands
– Be able to describe/identify the different phases of population change, how and why
birth and death rates change, and their influence on total population
– Carrying capacity for humans on Earth – be able to describe and explain what the
limiting factors on human population growth might be
– Understand that human resource use per capita is not equal throughout the world and
that rapid development around the world will have a more significant effect on future
carbon emissions than population rise
Lecture 24 – Earth’s past climate
– Be aware that there are many different components of the “climate system”
– Be able to describe and explain how we can reconstruct the history of climate on Earth
– Be able to describe/explain/draw diagrams of why climate changes and on what
approximate timescales:
o Variations in amount/distribution of incoming energy
o Variations in amount of incoming energy reflected
o Variations in amount of outgoing energy absorbed
o Internal variability of the climate system
– Have a rough idea of how climate has changed over the last 100 million years and be
able to explain why
o Middle Cretaceous much hotter, no ice, sea level higher – due to CO2 levels and
position of continents/oceans
o Gradual cooling from 50 million years ago to today due to decreasing
greenhouse gases and plate tectonic changes
o Last 2 million years – glacials (cold periods) and interglacials (warm periods) due
to Milankovitch cycles and amplifying feedbacks
▪ Last interglacial (120,000 years ago) – temperatures similar to today,
part of Greenland/Antarctic ice sheets melted so sea level 6m higher
▪ Last glacial maximum (20,000 years ago) – colder, drier and dustier,
large ice sheets so lower sea level
o Last 10,000 years – our climate has been relatively warm and very stable
allowing agriculture and civilizations to develop
Lecture 25 – Earth’s climate today and in the future
– Be able to describe how our climate has been changing
– Be able to explain what factors are causing our climate to change today
– Be able to interpret diagrams which show the radiative forcing of different factors e.g.
greenhouse gases, solar variability, aerosols
– Be able to explain how we predict future changes:
o What factors are included in climate models
o What are some of the major uncertainties in the climate models
o What are “Representative Concentration Pathways (RCPs)” and what different
factors do they consider
– Have a rough sense of how our climate may change by 2100 and be able to give
examples of how these changes may affect human populations and ecosystems
Lecture 26 – Future climate change
– Be able to describe/explain/give or identify examples of how we can prevent worst case
scenario climate changes through:
o conservation
o efficiency
o carbon-free energy
o carbon-capture and storage
o geoengineering
– (The information about US emissions, the Paris Agreement, and recent
political/legislative actions will not be included on the final – it is just important for any
US resident to know!)
Overall
– Be able to describe interconnections between the spheres making up the Earth system
Sample questions for ESS 1 Exam 4 Answer Key
1. Biogeochemical cycle of phosphorus
Below is a figure showing a simplified phosphorus cycle. The units are in Mt (million tons) or Mt/yr
(million tons per year).
a) Fill in the table below to summarize the residence times of phosphorus in various reservoirs of the
cycle?
Reservoir
Amount of P (Mt)
Total sinks or sources
Residence time (yrs)
of P (Mt/yr)
Land plants
3000
60
50
Dissolved P
90,000
2
45,000
b) Farming practices over the last 50 years have resulted in much more soil erosion so increased
rates of runoff of soils to the ocean. If rates of runoff continue to increase rapidly what problem
might that cause for human populations?
If rates of runoff increase then the amount of soil (and phosphorus on land) will decrease which may
limit our ability to grow enough food to feed our increasing population. Increased phosphorus in the
oceans may result in more “dead zones” that may reduce the fish population and affect the amount
of food available for humans, as well as the economy and tourism.
2. Food webs and productivity
a) From the food web above, which of the organisms listed are autotrophs? How do they produce
organic molecules?
Ice algae and phytoplankton are autotrophs. They produce organic molecules using photosynthesis.
b) What is the trophic level of polar cod in the food web above? (Note – depending on the pathway you
choose the number might be a bit different.)
3rd – 4th trophic level
c) How do polar bears obtain energy?
By consuming other organisms and carrying out respiration where organic molecules are broken down
to produce CO2, water and energy.
d) Polar bears use sea ice in the Arctic to hunt from in the summer. How might the population of polar
bears change over the next 100 years and why? Why are polar bears more susceptible to extinction than
small zooplankton?
Polar bear populations are likely to decrease over the next 100 years because the summer Arctic sea ice
that they rely on is melting rapidly. Polar bears are more susceptible to extinction because they are
large, specialist species so are less adaptable to a changing environment. They require a large area to
hunt for their food, and they also reproduce slowly (only 1-2 pups every 3 years). This mean that the
population can take much longer to recover if some individuals die.
e) What factors control primary productivity in the oceans?
The factors that control primary productivity in the oceans are nutrient availability in the surface ocean,
and the availability of sunlight (for photosynthesis) in the deep ocean.
f) What factors control primary productivity on land?
The factors that control primary productivity on land are precipitation and temperature.
g) How might climate change affect primary productivity on land?
Climate change might affect primary productivity on land by changing the temperature which may
influence which crops can be grown. Also it may affect precipitation patterns and the amount of
evaporation and so how much freshwater is needed and available for plants to grow.
6. Past climate
a. Name and describe two ways that we can find out how aspects of our climate have varied in the
past (before there were instrumental records).
Any 2 of:
– geologic records e.g. dry lake beds would indicate that conditions were wetter in the past or
fossils indicating different conditions in the past
– layered proxy records e.g.
– tree rings (trees grow more in more favorable climate conditions for that species)
– lake records (contain pollen from local vegetation or remains of plankton which are
affected by climate conditions at the time they lived
– ice cores contain bubbles of ancient air and the chemistry of the water allows you to
reconstruct temperature at the core location
b.
Draw a line between the Milankovitch (orbital) cycle and its description.
Eccentricity
A 23,000 year cycle related to whether the
northern hemisphere is tilted towards the sun
at the perihelion or aphelion
Precession
A 41,000 year cycle related to changes in
the tilt of the Earth’s axis of rotation
Obliquity
A 100,000 year cycle related to how spherical or
elliptical the Earth’s orbit is around the sun
c. What would the following do to global temperature and why?
i. Decrease the amount of ice on the planet
A decrease in ice would decrease the albedo of the Earth and cause global temperature to
increase.
ii. A huge volcanic eruption
A huge volcanic eruption would release CO2 into the atmosphere which could increase global
temperature but it would also release aerosols into the atmosphere which, depending on what
they are and where in the atmosphere they are, could cause either a warming or cooling of
global temperature.
iii. Large scale deforestation
Large scale deforestation could cause an increase in albedo which would decrease temperature
but the main effect is to release large amounts of CO2 into the atmosphere which would cause
global temperature to rise.