Download Modeling Earth`s Climate Teacher Guide

Modeling Earth’s Climate
Teacher Guide
Overview
There are individual teacher guides for each of the five activities that make up the
climate investigation. Each teacher guide has student learning goals, suggestions for
classroom discussion questions, model highlights, and answers to embedded
assessments.
Modeling Earth’s Climate
Activity 1: Climates of Past, Present, and Future
Overview
This first activity sets the stage for the rest of the climate investigation. Students are
introduced to the unanswered question about the future of Earth’s climate. They
explore data from NASA showing temperature changes over the past 120 years and
data from the Vostok ice core to look at climate trends over different time scales.
Additionally, students are asked to evaluate what information the data provides and to
consider the limitations of conclusions that can be drawn from the data. Finally,
students meet a leading climate scientist to see how he approaches the same topic.
Learning Objectives
Students will be able to
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engage with the “unknown question” guiding the unit.
explore and critically analyze real-world data.
make claims about the data and determine their own level of certainty with regard
to their claims.
explain how scientists use climate models to explore changes in past and
present climates.
Lesson Plan
1. Estimated Time
This activity should take approximately 45 minutes.
2. Introduce the Activity
In this activity, your students will explore the question “What will the climate of the future
be like?” It is important to emphasize that this curriculum is not exploring whether or not
the Earth is warming. Rather, it explores how much the Earth will warm in response to
changes in the concentration of atmospheric CO2. Earth is a complex system and
scientists must take into account the interactions of many variables.
As students run the activity, have them focus on the trends in the graph and the graph
scales. In upcoming activities, graphs will be an important output of the model, so their
ability to interpret graphs is a critical foundational skill.
Section Highlights
Section 1: Looking for Trends in Earth’s Temperature—This section is divided into four
pages. Students will look at different representations of climate change over time. The
first graphs show climate change over the past century. The later graphs show climate
change over 400,000 years. Students should note the natural variability; Earth’s climate
has gone through glacial periods and interglacial periods.
Section 2: Beyond Trends in Earth’s Temperature—In this section, Dr. Daniel Schrag, a
leading climate scientist, introduces the inherent difficulty regarding predicting future
climate change. A recurring theme throughout this curriculum is evaluating the inherent
uncertainty scientists have with data they have collected and how well the data can
predict the future when placed in current climate models.
What can scientists say with certainty? – “Glaciers will melt if current trends continue,” –
and what they can’t say? – “In 50 years, Earth’s temperature will be eight degrees
higher, on average, than the current temperature.”
3. Discuss the Activity
Possible discussion questions:
Scale of climate change and natural variability
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Why don’t you see the climate trend in the first graph represented in the
graph from the Vostok ice core?
What is the average temperature difference between glacial periods and
interglacial periods?
How long (in thousands of years) did it take to go from glacial period to a
warming period?
How do these changes compare to the time scale for the changes we are
seeing now?
Predicting the future
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Why do you think scientists think the warming of the 20th century cannot
be explained by natural variability seen over geologic time?
Dr. Schrag stated in the video that humans are conducting an experiment
on Earth, and that no one will know with certainty what will happen in 100
years. Of what do you think he is certain? What don’t we know for
certain? To which experiment is he referring?
4. Answers to Questions
Section 1: Looking for Trends in Earth’s Temperature
Page 1: Climates of the Past
Q. What do the colors indicate about the change in average temperature over time from
1881 to 2007?
A. The colors suggest that the average temperature was two degrees below the 19501980 average in the 1800s, and more recently, between one and two degrees above
the 1950-1980 average.
Q. Where do the biggest changes in temperature occur?
A. The greatest fluctuations are at the polar regions.
Page 2: Trends of the Past
Q. Describe how Earth’s average temperature changed from 1880 to 2010.
A. Earth’s temperature fluctuated, but the general trend is an increase in temperature.
Q. The green bars are called “error bars.” They indicate the range of uncertainty that
scientists have about the data on the graph. Why do you think these error bars are
smaller near the year 2000 than in the 1890s?
A. They are smaller because the data scientists collected in 2000 was obtained from
instruments with more precision and greater reliability than the data collected with
instruments in the 1890s.
Page 3: Trends of the future
Q. On a scale from 1-5, how certain are you about your graph predicting the
temperature through the year 2100?
A. Student answers will vary.
Q. Explain what factors might affect your level of confidence in the previous question.
A. Student answers will vary. Students may indicate that there is not enough data to
predict the future. They may reason that the trend seems clear, but they don’t know
what other factors might affect how warm Earth gets.
Page 4: Looking Further Back in Time
Q. The graph shows that climate for the past 10,000 years has been …
A. Staying fairly stable.
The graph does not indicate stability, but it does indicate cyclic regularity. It is an
unstable climate (ups and downs), but the cycles occur in a regular repeating pattern.
Q. Describe how current climate trends (as shown in the 120-year graph on the last
page) MIGHT change the pattern of warming and cooling as shown on this graph.
A. If the trends continue, the Earth will show rapid warming that is not followed by a
cooler period.
Section 2: Beyond Trends in Earth’s Temperature
Q. Though scientists generally agree that global warming is occurring, there are still
many unknowns about what exactly will happen to Earth and the environment as a
result of global warming.
Explain how scientists can be both fairly certain of global climate change and still
actively researching the unknown factors.
A. Student answers will vary, but students should indicate that scientists understand
that humans are contributing to warming of the climate and that scientists are certain
that Earth’s climate will warm. However, scientists are studying the interactions of
Earth’s system to better understand what might happen. For example, scientists are
still actively exploring the interactions of the ocean and CO2 in the atmosphere as well
as many other factors that are not yet completely understood.
Modeling Earth’s Climate
Activity 2: Solar Radiation and Greenhouse Gases
Overview
In this activity, students explore how solar radiation interacts with Earth’s surface and
atmosphere. They do this by exploring two types of models: one at the molecular level
and one at an Earth system level. In this activity, students are introduced to models that
allow them to explore how carbon dioxide, a greenhouse gas, relates to Earth’s
temperature. Finally, students interpret real-world data on CO2 trends from recent
history and geologic time.
Learning Objectives
Students will be able to
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describe what happens when solar radiation interacts with Earth’s surface and
atmosphere.
determine how CO2 and other greenhouse gases cause Earth’s temperature to
warm.
explore and critically analyze real-world data about changes in atmospheric CO2
over Earth’s history.
Lesson Plan
1. Estimated Time
This activity should take approximately 45 minutes.
2. Introduce the Activity
In this activity, your students will explore two different modeling environments. It is
exceptionally important to discuss scales of measurement and what each model
represents.
The first model (on page 1) is an Earth system model. You may want to walk your
students through each of the features and the controls for the model. Ask students to
identify different aspects of the model and talk about how each of the controllers work.
It is very important to bring students’ attention to the speed control just above the
model window. They can control how fast or slow the model runs. When the model
speed is slow, students can follow different elements clearly; when it is run fast,
students can observe what happens on the graphs to the left of the model.
The second model (on page 2) is a molecular model. Again talk to your students about
scale; molecules are not visible to the naked eye, but models help us to understand
interactions that occur at the molecular level. Discuss with your students how this
model compares to the Earth system model. Particularly, you should highlight the heat
energy shading. Let them discover how the molecules heat up when sunlight interacts
with them and how this is represented by a more intense shade of red. Also, make sure
that they identify how heat is lost from the molecules when infrared radiation leaves the
models. Finally, talk about the molecular motion that they observe. Molecules move
faster when heated.
NOTE: Spend time discussing the “Temp-Change” graph to the left of the Earth system
model. Review what they learned about the computation of temperature anomaly (from
the temperature anomaly graphs) in Activity 1 and how it is represented on this graph.
3. Discuss the Activity
Possible discussion questions:
Interactions with Earth’s Atmosphere
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What do the models help you visualize?
What are the limitations of the models in this activity?
What does the “Temp-Change” graph show?
Based on the models, what is the relationship between atmospheric CO2 and
temperature?
Why do you think Charles Keeling’s CO2 graph (page 4) fluctuates so regularly?
What do you notice about Earth’s climate over geologic time?
4. Answers to Questions
Section 1: Looking for Trends in Earth’s Temperature
Page 1: Carbon Dioxide in the Atmosphere
Q. What two things can happen when energy from the Sun interacts with the ground?
Click the button labeled “Follow an energy packet” for a hint.
A. The energy can bounce of the ground and head back out into space (it is reflected)
or it can be absorbed by the ground and turn into heat. It may then be reflected as IR
radiation.
Q. How is CO2 shown in this model?
A. They are shown as moving green dots.
Q. Describe the effect of carbon dioxide on global temperature.
A. The more CO2 in the atmosphere, the higher the global temperature. When you
lower CO2, the global temperature decreases.
Q. What happens if you remove all the CO2 from the atmosphere?
A. The global temperature decreases significantly.
Page 2: Radiation-Greenhouse Gas interactions.
Q. What happens when the sunlight hits particles in the ground? Try resetting the model
and turning on the “Heat Energy Shading.”
A. The ground particles jiggle more and get heated up. This is shown by them getting
redder.
Q. Based on the Earth system model (from the last page) and the molecular model
(above), what can happen to solar energy when sunlight hits the Earth's surface?
A. The solar energy is absorbed by the particles in Earth surface and the energy is
transferred to Earth’s surface. Eventually that radiation is reflected back to space from
Earth in the form of IR radiation.
Q. What happens when infrared radiation hits the greenhouse gases? (Hint: Watch
carefully to see what happens when an infrared beam hits a molecule. Let the model
run long enough for you to see a change in the temperature graph.)
A. When a beam hits a molecule, a dashed line appears around it and then an infrared
beam shoots off the molecule in a different direction. The bar graph shows the
temperature increasing.
Q. Based on the Earth system model and the molecular model, how do carbon dioxide
(CO2) and other greenhouse gases cause the Earth's atmosphere to warm?
Greenhouse gases
A. absorb and re-radiate outgoing infrared radiation.
Page 3: Reconciling the Models
Q. Explain the similarities between the molecular model and the Earth system model.
A. Both models show incoming solar radiation, the Earth absorbing some of the
radiation and the radiation transforming into heat, and then the Earth radiating infrared
radiation. Both models show the CO2 in the atmosphere also absorbing and reemitting
infrared radiation. Both models show the Earth’s temperature increasing when CO2 is
heated.
Q. Which factor is represented by the red arrows in the Earth system model? What
evidence do you have to support this?
A. The red arrows represent infrared energy. When you follow an energy packet, you
see the energy converted to heat and then radiated out as an infrared energy packet.
Page 4: The Keeling Curve-Atmospheric CO2 over the last 50 years
Q. What are some causes of the carbon dioxide increase over the past 50 years?
A. Student answers will vary. Students should suggest human produced CO2 such as
burning fossil fuels, cutting down and burning rainforests. Others may suggest some
natural variation such as volcanic eruptions.
Page 4: Atmospheric CO2 in Prehistoric Times
Q. How many years of data are available from the Vostok ice core?
A. 410,000 years.
Q. Why is some of the data shown with a blue line and other data shown with a red
line?
A. The blue data was measured by sampling the ice and the red data was measured
directly from the air.
Q. How does the temperature 100,000 years ago compare to the temperature 400,000
years ago?
The temperature 100,000 years ago was likely
A. cooler than 400,000 years ago.
Q. How certain are you of your answer to the last question? What factors influence
your uncertainty?
A. Student answers will vary for uncertainty. Possible factors that influence their
uncertainty should include the exact relationships between temperature and carbon
dioxide levels. Some students may go back to the first activity to look at the
temperature graph from the Vostok ice core years if they recognize that the carbon
dioxide measurements are from the same time period as the temperature graph.
Modeling Earth’s Climate
Activity 3: Sources, Sinks, and Feedback
Overview
In this activity, students explore the relationships between ocean surface temperature
and carbon dioxide sequestration, atmospheric carbon dioxide levels and the amount of
atmospheric water vapor, and the relationships between all three—carbon dioxide
concentration, water vapor, and oceans.
Learning Objectives
Students will be able to
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describe how carbon dioxide travels through Earth’s system and identify sources
and sinks for carbon dioxide.
explain how temperature affects the ocean's ability to absorb carbon dioxide.
explain the role of water, a greenhouse gas, on Earth’s temperature.
explain the effects of temperature on carbon dioxide uptake by the oceans and
water vapor in the atmosphere.
describe an example of a positive feedback loop in the Earth system.
explain why it is necessary to consider multiple factors when modeling climate.
Lesson Plan
1. Estimated Time
This activity should take approximately 45 minutes.
2. Introduce the Activity
In this activity, your students will interact with models showing how carbon dioxide
cycles into the ocean. They will be able to manipulate the surface temperature of the
ocean to determine the relationship between ocean temperature and carbon dioxide
uptake.
After determining this relationship, your students will use a more complex model in
which they can observe the changes in atmospheric water vapor as ocean temperatures
change. In the final model of this activity, your students can explore the complete
relationship between ocean surface temperature, atmospheric carbon dioxide
concentration and uptake, and atmospheric water vapor concentration.
3. Discuss the Activity
Possible discussion questions:
Carbon Dioxide Cycling
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What are some sources of CO2?
If CO2 is added by all these sources why isn’t the atmospheric concentration
much higher?
How is the solubility of CO2 affected by temperature?
How do atmospheric CO2 levels affect ocean surface temperatures?
Water Vapor in the Atmosphere
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What is the effect of atmospheric water vapor on temperature?
How does water vapor help to trap heat in the atmosphere?
Which is a better greenhouse gas: carbon dioxide or water?
What is the end result of the positive feedback relationship between CO2 and
water vapor?
What effect of water vapor is missing from these models?
4. Answers to Questions
Section 1: Carbon Dioxide Cycling
Page 1: Carbon Cycling in the Earth System
Q. Which statement is true about biogeochemical cycles?
A. Substances are constantly moving through the environment.
Q. Is there a reservoir in the Earth system that serves only as a sink for carbon dioxide?
Explain your reasoning.
A. No, there is not a reservoir in the Earth system that serves only as a sink. The
biogeochemical cycle shows that substances are constantly moving through the
system. If they stop at a sink, then that means that the entire cycle would shut down.
Page 2: Carbon Dioxide Solubility in the Ocean
Q. Before you run the model, predict what effect temperatures will have on the ability for
CO2 to dissolve in the ocean.
Increased temperature will result in MORE/LESS CO2 being absorbed by the ocean
BECAUSE...
A. Student answers will vary. The logic should be consistent with what they learned
about carbon dioxide and temperature in Activity 2.
Q, How does temperature affect the amount of carbon dioxide that the ocean can
dissolve?
A. When the temperature is higher, less carbon dioxide can be absorbed by the ocean.
Q. Which statement best describes the relationship between temperature and the
solubility of carbon dioxide in the ocean?
When Earth's temperature is higher,
A. less carbon dioxide can be dissolved in the ocean.
Q. What happens to the carbon dioxide that sinks to the bottom of the ocean? For a
hint, look at the sample biogeochemical cycling pathway on the previous page.
A. The carbon dioxide is incorporated into rocks, which then can be weathered and
release the CO2 to the atmosphere again.
What is the relationship between atmospheric CO2 levels and its absorption by the
ocean?
A. If CO2 levels are higher, the temperature will be higher. When the temperature is
higher, less carbon dioxide can be absorbed by the ocean, which means that there is
more CO2 in the atmosphere, leading to higher temperatures.
Section 2: Water Vapor in the Atmosphere
Page 1: Water Vapor is a Powerful Greenhouse Gas
Q. Describe the relationship between water vapor and temperature.
A. When the temperature is high, there is more water vapor.
Q. When there is more water vapor in the atmosphere, what will happen to the
temperature?
A. The temperature will increase when there is more water vapor in the atmosphere.
Page 2: Water as a Greenhouse Gas
Q. Based on the interactions in the whole Earth model and in the molecular model,
which greenhouse gas is more powerful (can raise the temperature faster)--water vapor
or carbon dioxide? How can you tell?
A. Water vapor is more powerful because it raises the temperature faster than carbon
dioxide does.
Page 3: The Effect of Two Different Greenhouse Gases Combined
Q. How does the level of carbon dioxide affect the level of water vapor in the
atmosphere?
A. increases (Increased carbon dioxide increases atmospheric water vapor.)
Q. Explain your answer.
A. When the carbon dioxide level is increased, the temperature increases. When the
temperature increases, the amount of water vapor that can be in the atmosphere
increases.
Q. What happens to the temperature in the model?
The temperature
A. increases.
Q. Why?
A. The temperature increases because carbon dioxide and water are both greenhouse
gases. The carbon dioxide increases the amount of water vapor in the atmosphere,
which increases the temperature, pushing more water vapor into the atmosphere, which
raises the temperature higher.
Page 4. Multiple Factors go into Climate Modeling
Q. Describe OR sketch out the positive feedback system that affects Earth's climate.
A. When carbon dioxide increases, temperature increases. This increases the amount
of water vapor in the atmosphere. With increased levels of greenhouse gases in the
atmosphere, more heat is trapped, making the temperature higher. In addition, carbon
dioxide is not effectively removed by the ocean since the temperature is higher, making
it more likely that the temperature will continue to rise.
Q. Based on what you've learned so far, are carbon dioxide and water likely to be the
only factors that affect global temperature?
A. No. There needs to be something to bring the temperature down because the
temperature doesn't continually increase.
Q. What are other possible factors? How would these affect the temperature?
A. Student answers will vary. Some possible factors that would decrease temperature:
clouds, pollution (smog), precipitation.
Modeling Earth’s Climate
Activity 4: Feedbacks of Ice and Clouds
Overview
In this activity, students explore albedo, changing the amount of ice and cloud cover to
examine how different surfaces provide negative and positive feedbacks to temperature
increases caused by increased levels of greenhouse gases.
Learning Objectives
Students will be able to
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learn that the proportion of sunlight reflected from the earth’s surfaces, a quantity
called albedo, affects the energy absorbed.
explore the positive feedback between temperature and ice cover.
explore the negative feedback between and cloud cover and temperature.
understand that there are uncertainties in the feedbacks of temperature, water
vapor and cloud cover that complicate scientists’ ability to predict future climates.
Lesson Plan
1. Estimated Time
This activity should take approximately 45 minutes.
2. Introduce the Activity
Ask your students how ice, snow, and clouds might affect global temperature. Before
they start to work with the models, remind them that they should be looking for
relationships between the variables. Have them focus on the “Temp-Change” graph as
they make changes in the amount of ice and clouds.
Section Highlights
Section 1: Ice in the Earth System —Students perform a series of experiments to test
the effect of albedo on the Earth’s temperature, first changing the amount of ice cover,
then changing the albedo values.
Section 2: Clouds —This cloud model oversimplifies the complicated role that clouds
play in albedo and energy balance. Recent data indicates that low fluffy clouds
(cumulus) reflect much of the sunlight that falls on them, giving them a high albedo.
However, high thin clouds (cirrus) transmit much of the sunlight that falls on them, but
they also tend to absorb and re-radiate infrared radiation from Earth. Thus, low clouds
produce a cooling effect, while high clouds produce a warming effect.
This model addresses only the net cooling effect of clouds. This is an important
negative feedback relationship that counteracts the positive feedback of increased
atmospheric water vapor, as clouds are composed of water vapor.
Section 3: Exploring real-world cloud and ice interactions—This section includes
photographic and data-based evidence of melting ice sheets. Students are asked to
make predictions and analyze their level of certainty with the data.
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3. Discuss the Activity
Possible discussion questions:
Ice, Snow, and Clouds
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How do ice, snow, and clouds affect temperature?
Why is it colder on clear nights than on cloudy nights?
Activity Synthesis
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If sea ice melts, how might that affect global temperature and the
atmospheric concentrations of carbon dioxide and water vapor?
What happens in a negative feedback cycle?
What happens in a positive feedback cycle?
4. Answers to Questions
Section 1: Ice in the Earth System
Page 1: The Surfaces of Earth
Q. What happens when energy from the sun encounters a white surface (ice or snow)?
The energy is
A. reflected off the surface and leaves the atmosphere.
Q. Describe how changes in the amount of ice covering Earth’s surface can affect
Earth’s temperature?
A. Because ice and snow reflect more sunlight than most land surfaces and water, the
larger the area of ice or snow, the more sunlight is reflected back into space and less
solar energy is absorbed. Only the absorbed sunlight causes a rise in temperature.
Page 2: Experimenting with Albedo
Q. Experiment #1. Cover Earth’s surface with ice by setting the “%-Ice-cover” slider to
100%.
What would Earth’s climate be like if the albedo of ice were close to 0? Describe your
results below.
A. If the earth had an albedo of 0, all of the visible solar radiation would be absorbed
and the global temperature will increase.
Q. Experiment #2: Set ice cover to 100% again.
What would Earth’s climate be like with an ice albedo value closer to 1?
A. If the earth had an albedo close to 1, nearly all of the visible solar radiation would be
reflected, and the temperature would decrease.
Q. Compare the results of your experiments with albedo.
A. The experiments show that low values of albedo result in most of the energy from the
sun being absorbed and higher temperatures. High values of albedo result in most of
the sun’s energy being reflected back into space and lower temperatures.
Q. Experiment #3: Currently about 10% of the Earth is covered with ice year-round.
Assume the albedo of ice is close to 1.
If this ice melts, what could that mean for the Earth’s climate?
A. If the 10% ice cover melts, the surface below will be exposed which will lower the
Earth’s albedo. The surface underneath has lower albedo, which means that more
solar energy will be absorbed, leading to increased temperatures.
Section 2: Clouds
Q. In this model, how do the changes in cloud cover affect the Earth’s temperature?
A. The greater the number of clouds, the lower the temperature.
Q. Take a snapshot of a model that shows cloud cover that decreased Earth's
temperature.
A. Student answers will vary.
Q. How do the energy packets interact with the clouds to cool the Earth?
A. When there are a lot of clouds, there is a greater chance that the incoming solar
energy or outgoing infrared radiation will encounter a cloud. When the solar energy
packet hits a cloud, it is reflected back into space, which decreases the amount of
energy that reaches Earth, thus decreasing the temperature. The infrared radiation can
pass through the clouds, which means that Earth can still lose heat energy to space.
Without the heat loss being offset by incoming solar radiation, the Earth cools.
Q. The clouds cause a decrease in warming. This is called negative feedback, where a
stimulus (heating) results in a feedback (clouds) that counteracts the stimulus (cooling
effect).
Contrast this with the positive feedback relationship of water vapor and temperature
increases.
A. As temperature increases, more water will evaporate, making more water vapor.
Since water vapor is a greenhouse gas, it tends to increase the temperature even more
as it absorbs and reflects infrared radiation.
When there are clouds, the temperature decreases because the clouds prevent more
radiation from being absorbed. The negative feedback reverses the temperature
increase and the positive feedback increases the temperature increase.
Section 3: Exploring real world cloud and ice interactions
Q. How might the trend shown in the graph affect Earth’s temperature in the year 2100?
A. It will increase the temperature.
Q. Explain your prediction.
A. The trend (blue line) shows that the extent of sea ice has been decreasing at a
constant rate for the last 30 years. Since ice reflects sunlight much better than water,
as the extent of ice decreases, more of the Sun’s energy will be absorbed into the water
in the arctic region, causing it to warm.
Q. On a scale from 1 to 5, how certain are you about your temperature prediction for
the future?
A. Student answers will vary.
Q. Explain what affects your level of certainty about your prediction for temperature
change.
A. Student answers will vary. Students may include uncertainties about the level of
carbon dioxide and the amount of cloud cover that may result from the evaporation of
more water.
Q. Do you think that the ice melting is an example of positive feedback or negative
feedback? Explain your answer.
A. This is an example of positive feedback because the change keeps occurring and
accelerates. When the ice melts, it results in more solar energy absorption, which
increases the temperature and melts more ice. If it were negative feedback, the melting
ice would cause more water to freeze and make more ice to stop the process. This
does not happen, so it is positive feedback.
Q. Based on this information, how is the model both a good and poor representation of
the Earth system?
A. Student answers will vary. The model is a good representation of the system
because it shows the positive and negative feedbacks that affect the global
temperature. It is a poor representation because it does not account for the different
types of cloud interactions with visible and infrared radiation. It also doesn't account for
the different topography of places on the Earth, such as mountains, on which falling
precipitation would be more likely to be snow, increasing the albedo of the surface. The
model also does not take into account ocean currents, which distribute heat around the
planet.
Modeling Earth’s Climate
Activity 5: Using Climate Models
Overview
In this final activity of the climate investigation, all of the variables and feedbacks from
the previous four activities have been linked together. Students will be able to see how
all the variables interact with each other to produce global temperature effects.
Students can change only the initial temperature and the CO2 emissions, setting up the
model for experimentation; they are challenged to run the model to produce particular
results, such as an ice-age. The challenges require students to synthesize the
concepts from the previous activities and allow students to tell a story about how climate
change occurs.
Learning Objectives
Students will be able to
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set up experiments using the models and interpret the results.
explore the complex inter-relationships between the variables that affect global
temperature.
make predictions about experimental outcomes based on the starting conditions.
analyze the level of uncertainty in the data generated by the model.
defend their predictions based on their understanding of climate variables.
Lesson Plan
1. Estimated Time
This activity should take approximately 45 minutes.
2. Introduce the Activity
Tell your students that they will be performing two experiments with a climate model that
incorporates all of the factors they have encountered in the previous activities. Explain
to your students that they will “warm up” their experimentation skills with the model on
the first page. After completing the first challenge, they will be able to choose their own
experiment from one of two different challenges to explore on the next two pages.
Help your students to devise a method for experimenting with the model. The goal is to
get a stated outcome. Advise your students to think about the effects of the different
variables as they set up the model conditions. For instance, if the goal is to create an
ice age, and students can change only the carbon dioxide level, ask them to think about
how the level of carbon dioxide can affect the amount of ice.
It is very important to stress to your students that experiments are done to figure
out the answer; scientists do not know the right answer before they run
experiments. It is okay for them to “fail” to reach the stated goal, but they should be
encouraged to learn from their failures to change the model setup for future
experiments.
Remind your students to take notes of their setup conditions and any changes
that they make while the model is running so that they have a record of what they've
tried with the associated outcomes. Show your students how the “Take a snapshot”
button works, and encourage them to take pictures of their model at the start, when they
make any changes, and at the end of the experiment. They can use these pictures as
evidence for how they solved the challenge. Remind them that they will need their
pictures and notes as evidence to answer questions after the challenge. Your
students can use the built-in “Lab Book” to save their pictures and notes—show them
how to add pictures to their “Lab Books” after they take a snapshot.
Knowing when to end an experiment requires some judgment. Discuss with your
students how they will know when they have reached the stated goal. Remind them
that climate change takes place over long periods of time.
Finally, remind your students about the speed slider across the top of the model. The
speed can be made faster to see results more quickly when they don’t need to watch
the details of the interactions of model components. Note that when the model is
running very fast, it appears to be running more slowly because the main screen is
redrawn only every few seconds. However, the underlying calculations and the graph
plotting occur nearly instantaneously.
Page Highlights
Experiment with the model.—This initial experiment—finding a setting of human
emissions that cools the atmosphere— serves as practice for the challenges that follow.
Encourage students to take notes on their experiments and to look for patterns as they
try different settings.
Have students describe in detail what they found. What was the emission setting? How
long did it take to lower the temperature? Did it stay lower? It is very useful for
students to try this experiment several times even if they believe they have achieved the
goal on the first try. The goal, as stated, is deliberately a little vague. Should they find
the smallest change that can lower temperature or any change that decreases
temperature? If students are successful with the challenge, challenge students to find
the smallest emissions change that maintains the same temperature and determine how
much temperature can be lowered by further emissions.
Challenges 1 and 2 (pages 2 and 3)—Students need to use their understanding of
climate variable interactions to predict the model's starting conditions to reach a stated
end goal. Remind students to keep thorough notes and pay attention to patterns and
relationships between climate variables. Students will likely need to analyze the output
from their initial starting conditions and modify those starting conditions to reach the
stated end goal.
3. Discuss the Activity
Possible discussion questions:
The nature of experimenting with a model
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For the challenge that you chose, how did you decide what values to try
for the initial settings?
After trying a few experiments, how did you decide what settings to try
next?
Did patterns in the data start to emerge that helped you work toward
achieving the challenge?
How did you decide when it was time to end an experiment?
The nature of scientific certainty
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How is the scientific process you used useful for predicting how much
temperature might change in the future?
Dr. Schrag stated in the video (on the first day) that humans are
conducting an experiment on Earth, and that no one will know with
certainty what will happen in 100 years. Of what do you think he is
certain? What don’t we know for certain? To what experiment is he
referring?
Given your level of uncertainty about the future of climate, what steps
should humans take to modify the pace of global warming?
4. Answers to Questions
Page 1: Experiment with the Model
Q. How much did you need to change human emissions to reduce the average global
temperature?
A. Using the default starting temperature (13°C), a reduction of emissions of at least
50% is necessary to maintain that temperature. Larger reductions can cool the average
temperature.
Q. Explain your conclusion by describing the experiments that you have run and their
outcomes.
A. Student answers will vary. Answers should include the emissions setting, how long
it took to lower the temperature, and the final temperature difference.
Page 2: Challenge 1: Which effect is stronger: clouds or water vapor?
Q. Prediction: As ice sheets melt, Earth’s temperature will:
A. Student answers will vary. If students understood the positive feedback of the icealbedo effect, they should predict an increase.
Q. Explain your temperature prediction.
A. Student answers will vary. Their explanations should justify their prediction and be
based on evidence from prior activities.
Q. On a scale from 1 to 5, how certain are you about your temperature prediction?
A. Student answers will vary.
Q. Explain what might affect your level of certainty with your temperature prediction.
A. Student answers will vary. Students should indicate their levels of certainty based on
their understandings of the inter-relationships between climate variables.
Q. Experiment with the model. How did you decide to set the CO2 emissions and
starting temperature?
A. Student answers will vary. They should include justifications for why they picked the
starting conditions they did, as well as an explanation of their thinking process.
Q. At the end of your experiment, take a snapshot of the model outcome. Did you meet
the challenge? Explain how your picture shows you met the challenge.
A. Student answers will vary. They should provide justification for how their pictures
show they met the stated goal.
Q. Insert a snapshot of the end result of your model.
A. Student answers will vary.
Page 3: Challenge 2: Create an Ice Age.
Q. Describe how you set up the model and why it produced the result it did.
A. Student answers will vary. Answers should include an analysis of the relationships
between climate variables.
Q. Rate your level of certainty with your selection of starting conditions for the model.
A. Student answers will vary.
Q. Explain what might affect your level of confidence in your model.
A. Student answers will vary. Look for evidence based on data in students’ responses.
Q. Insert a snapshot of the end result of your model.
A. Student answers will vary.
Q. Explain why your model did or did not produce an ice age.
A. Student answers will vary. They should use data from their models to explain their
success or failure to meet the goal, along with an explanation of what might be the
reasons for their success or failure. Explanations should match the snapshot of the
model.
Page 4: Climate and Society
Q. Based on what you learned from the models in this unit, describe how increased
atmospheric CO2 impacts global temperature and suggest two actions that might reduce
carbon emissions.
A. Student answers will vary.
They should be able to cite many effects from extra CO2 in the atmosphere. CO2
absorbs and re-radiates infrared radiation causing temperatures to rise. The
temperature rise reduces the solubility of CO2 in the ocean so more of it remains in the
atmosphere. The temperature rise causes an increase in atmospheric water vapor.
Water vapor absorbs and re-radiates infrared radiation, leading to increased heating in
a positive feedback loop. The temperature rise causes ice and snow melting that
results in the positive feedback of the ice-albedo effect.
Actions that can reduce CO2 emissions include capturing and storing of carbon dioxide
(sequestration), using less electricity, buying fewer goods made in far-flung locations
(decreasing transport of materials), burning fewer fossil fuels, using alternative sources
of energy that have no carbon dioxide emissions (solar, wind, hydro, wave energy,
geothermal, and nuclear), and increasing the number of plants that take up carbon
dioxide.