intermediate earth's changing climate (1) · the question of earth's future climate is...

INTERMEDIATE 14 Day Lesson Sequence

What is the future of Earth's climate? The High-Adventure Science Climate module has five activities. Explore the question, what will Earth's climate be in the future? Through a series of guided questions, you will explore interactions between factors that affect Earth's climate. Explore temperature data from ice cores, sediments, and satellites and greenhouse gas data from atmospheric measurements, run experiments with computational models, and hear from a climate scientist working to answer the same question. You will not be able to answer the question at the end of the module, but you will be able to explain how scientists can be certain that Earth is warming while not being entirely certain about how much Earth will warm.

Student: ________________ Teacher: ________________ Period: ____

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Lesson Sequence

Day 1: pages 3-9 What will Earth's climates be in the future? Trends of the past (part 1) Trends of the past (part 2) Day 2: pages 10-12 Predicting the future Way, way back in time

Day 3: pages 13-18 Vostok Research Station, Antarctica Predicting the future from the past Looking to the future Day 4: pages 19-22 Solar radiation Carbon dioxide in the atmosphere Day 5: pages 23-28 Radiation-gas interactions Earth systems & greenhouse gases Atmospheric carbon dioxide levels over time Day 6: pages 29-31 Historical carbon dioxide levels

Day 7: pages 32-34 Carbon cycling in the Earth system Day 8: pages 35-38 Carbon dioxide: solubility in the ocean Changing ocean temperature Day 9: 39-44 Water vapor: a powerful greenhouse gas Combining the effects of carbon dioxide and water vapor Multiple factors Day 10: 45-49 Ice on Earth's surface Clouds Day 11: pages 50-54 Melting glaciers Arctic sea ice Feedback: positive or negative? Clouds: cooling or warming?

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Day 12: pages 55-59 Complex climate models Time lags in temperature changes Meet a climate scientist: Mark Chandler Day 13: pages 60-63 Societal effects Millions of years of data Day 14: pages 64-68 How much reduction? ASSESMENT

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Module 1 Earth's changing climates What is the future for Earth’s climate? 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. Evaluate what information the data provides and consider the limitations of conclusions that can be drawn from the data.

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What will Earth's climates be in the future? The question of Earth's future climate is one of the most important unanswered scientific questions today. Climate affects all forms of life; it is an essential factor in determining how ecosystems work. Scientists know that the world has warmed over the last 10,000 years; humans have contributed to the warming of the past 100 years. How warm will Earth get? How fast will Earth warm? What will future climates be like?

In this module, you will examine climate data and models and explore what we might be able to predict about the future. Use the pictures below to answer questions 1-2 or go to https://earthobservatory.nasa.gov/world-of-change/global-temperatures

1880-1884 1890-1894

1900-1904 1910-1914

1920-1924 1930-1934

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1940-1944 1950-1954

1960-1964 1970-1974

1980-1984 1990-1994

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2000-2004 2010-2014

2015-2019

The pictures show the changes in Earth's temperature across the globe between 1880 and 2019. Compared to the baseline temperature between 1950 and 1980. Changes from the baseline are called anomalies. Bluer colors show places where the temperature was lower than the 1950-1980 average, and redder colors show places where the temperature was higher than the 1950-1980 average. Question 1 What do the colors indicate about the change in average temperature over time from 1880 to 2019?

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Question 2 In the past 50 years, where has the temperature changed the most?

Trends of the past (part 1)

The graph shows the temperature change (anomaly) from 1880-2010, compared to the average temperature from 1950-1980.

Each point on the graph is an average of the temperatures for the preceding 12 months (12-month running mean).

This is similar to what you saw in the movie.

Question 3

Describe the average temperature change from 1880 to 2010.

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Trends of the past (part 2)

This graph shows the global temperature changes again, this time with a little more detail.

The black points show the same data as the last graph (the annual average temperature, compared to the 1950-1980 baseline). The red line shows the five-year average (compared to the baseline), computed each year.

Question 4

Why is the curve between 1950 and 1980 relatively flat and centered around zero degrees difference from the baseline? (Hint: how is the temperature change being compared over time?)

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Question 5

The green bars are called "error bars." They indicate the range of uncertainty that scientists have about the data on the graph. (Note: Not all error bars are shown.) Why do you think these error bars are smaller near the year 2000 than in the 1890s?

Question 6 Why is the black line more irregular than the red line? What is the difference between the data they show?

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Predicting the future

Question 7

This graph shows the five-year running average from the previous page. It is clear that past temperature data has a trend. Does the past trend help us to predict the future?

How could we extend this graph to show the temperature in the next 100 years? Draw your prediction on the graph.

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Question 8

Explain why you drew your prediction.

Question 9

How certain are you about your prediction based on your explanation?

Not certain Very Certain

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Question 10 Explain what influenced your certainty rating.

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Way, way back in time

19 cm long section of GISP 2 ice core from 1855 m showing annual layer structure illuminated from below by a fiber optic source. Section contains 11 annual layers with summer layers (arrowed) sandwiched between darker winter layers.

The data for the previous graphs were obtained with thermometers. What if scientists wanted to know Earth's temperature before humans started collecting data?

Scientists have found a variety of techniques to determine the temperature before the existence of thermometers. By studying glaciers and ice sheets, scientists have been able to infer global temperatures over the past few hundred thousand years by studying the gases and other materials that are trapped in the ice.

Scientists take cores of the ice by drilling holes deep into glaciers and ice sheets. Since the layers at the bottom are older than layers at the top, scientists can see the changes in the trapped gases over a long period of time. The picture shows a 19 cm long section of an ice core from the Greenland ice sheet.

Question 11

Why do you think the winter layers are darker than the summer layers in the ice core?

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Vostok Research Station, Antarctica

Scientists take cores from glaciers, ice sheets, and sediments to study past climates.

The data in the graph comes from an ice core taken at the Vostok Research Station in Antarctica. The graph shows the temperature change from 420,000 years ago to the present, compared to the modern average temperature. (The present time is shown on the left side of the x-axis; 420,000 years ago is shown on the right side.) When the temperature on the graph shows a change of -3°C (or lower), Earth was in an ice age. When the temperature on the graph shows a change above the -3°C line, Earth was in an interglacial period, as it is today.

Temperature change, measured from dissolved gases Vostok Ice Core. Geology 101 - Introduction to Physical Geology Lab--Glaciers & Ice Age; Creative Commons Attribution 3.0 United States License CC-BY-3.0 The data in the graph comes from the publication by Petit, J.R., J. Jouzel, D. Raynaud, N.I. Barkov, J.M. Barnola, I. Basile, M. Bender, J. Chappellaz, J. Davis, G. Delaygue, M. Delmotte, V.M. Kotlyakov, M. Legrand, V. Lipenkov, C. Lorius, L. Pepin, C. Ritz, E. Saltzman, and M. Stievenard. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok Ice Core, Antarctica. Nature volume 399: pages 429-436.)

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Question 12 The trend in the graph shows short warm periods between long periods of highly variable cold climate. Which statement is supported by the information in the graph? The graph shows that the temperature for the past 10,000 years, compared with the previous 400,000 years, has been

getting warmer. staying fairly stable. getting colder

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Predicting the future from the past

You have just seen these graphs. Use these graphs to describe how current climate trends (first graph) might change the pattern of warming and cooling seen in the Vostok ice core (second graph).

Average temperature change, compared to 1950-1980 baseline, from 1880 to 2010

NASA Goddard Institute for Space Studies

Temperature change, measured from dissolved gases. Vostok Ice Core.

Geology 101 - Introduction to Physical Geology Lab--Glaciers & Ice Age; Creative Commons Attribution 3.0 United States License CC-BY-3.0

The data in the graph comes from the publication by Petit, J.R., J. Jouzel, D. Raynaud, N.I. Barkov, J.M. Barnola, I. Basile, M. Bender, J. Chappellaz, J. Davis, G. Delaygue, M. Delmotte, V.M. Kotlyakov, M. Legrand, V. Lipenkov, C. Lorius, L. Pepin, C. Ritz, E. Saltzman, and M. Stievenard. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok Ice Core, Antarctica. Nature volume 399: pages 429-436.)

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Question 13

Describe how current climate trends (from 1880 to 2010) might change the pattern of warming and cooling shown on the Vostok ice core graph.

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Looking to the future

1995 IPCC report projected global mean surface temperature changes from 1990 to 2100 for the full set of IS92 emission scenarios. A climate sensitivity of 2.5°C is assumed. Climate Change 1995 – The Science of Climate Change. Contribution of Working Group I to the Second Assessment Report of the Intergovernmental Panel on Climate Change, Figure 18 (TS). Cambridge University Press.

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We want to predict future climate, but simply looking at changes in temperature is not enough. The Earth is a complex system.

Scientists use mathematical climate models to try to predict what will happen to Earth's temperature in the future. The math is very complicated, so scientists use computer programs to do the calculations.

Still, these mathematical models are not complex enough to model the entire Earth system, so scientists design their models to focus on just a few of the components at a time. In the next four activities, you will use climate models to understand how the global temperature is affected by changes in the mix of gases in the atmosphere.

Although scientists generally agree that global warming is occurring, there are still many unknowns about what exactly will happen to Earth's many climates because of global warming.

Question 14

Explain how scientists can be both certain that Earth is warming and still actively researching the unknown factors.

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MODULE 2 Interactions within the atmosphere Explore how solar radiation interacts with components of Earth's surface and atmosphere, and learn how greenhouse gases warm Earth's atmosphere.

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Solar radiation

The Sun, Earth's atmosphere, and other systems interact to create conditions favorable to our life on Earth.

The model shows a simplified Earth system with land, atmosphere, and solar radiation. The yellow arrows show energy coming from the Sun.

Go to bit.ly/solarradiation

Start the model, and experiment with the controls to see how the model works.

Question 1

What two things can happen when energy from the Sun interacts with the ground? Click the button labeled "Follow Energy Packet" for a hint.

Question 2

How does carbon dioxide (CO2) interact with the two types of radiation (sunlight and infrared) shown in this model?

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Carbon dioxide in the atmosphere

Adjust the level of CO2 in the air by using the "Remove CO2" and "Erupt!" buttons. Explore the effect of carbon dioxide on the average global temperature. Use the CO2 in Atmosphere graph to see the level of carbon dioxide in the atmosphere. Go to bit.ly/co2activity Watch what happens to the temperature, shown on the Temperature Change graph, when the concentration of atmospheric carbon dioxide changes.

Question 3

How does atmospheric carbon dioxide affect global temperature?

Question 4

What happens if you remove all of the carbon dioxide from the atmosphere? The temperature

decreases. increases.

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stays the same.

Question 5

Explain your answer to question 4.

Question 6

How certain are you about your claim based on your explanation?


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Question 7

Explain what influenced your certainty rating.

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Radiation-gas interactions

How does solar radiation interact with Earth and its atmosphere to cause global warming?

Since all matter is made up of molecules, we can look at a molecular-level model to see what is going on.

Use the molecular model to explore how solar radiation interacts with Earth's surface and atmosphere. 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.

Go to bit.ly/radiationgas

Question 8

What happens when the sunlight hits particles in the ground? (Try resetting the model and turning on "Display heat in molecules." Redder shading means higher energy.)

Question 9

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What happens when the sunlight hits greenhouse gas molecules?

Watch the effects of sunlight and then watch the effects of infrared radiation, also known as heat radiation, on carbon dioxide, a greenhouse gas.

Glowing circles around the molecule show that a molecule has gained energy after absorbing radiation.

Question 10

What happens when infrared radiation hits the greenhouse gas molecules? How does the temperature change as a result?

Carbon dioxide is one of many different greenhouse gases. The greenhouse effect is what has made Earth so habitable for much of the life we see on a daily basis.

The greenhouse effect is a process in which heat coming from Earth's surface is prevented from escaping into space by greenhouse gases. As a result, Earth's temperature is higher than it would be if direct heating by the Sun were the only warming mechanism. The greenhouse effect couldn't work without energy from the Sun.

Question 11

Based on the Earth system model and the molecular model, how do carbon dioxide (CO2) and other greenhouse gases cause Earth's atmosphere to warm? (Choose all correct answers.)

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Greenhouse gases

absorb incoming solar radiation. reflect incoming solar radiation. absorb outgoing infrared radiation. emit outgoing infrared radiation.

Select the last choice on the model so that you can see the interactions of the solar radiation, ground, and greenhouse gases.

Question 12

Describe the similarities between the molecular model and the Earth system model.

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Earth systems & greenhouse gases

Go to bit.ly/greenhousegases1

Question 13

Which factor is represented by the purple arrows in the Earth system model? solar radiation infrared radiation greenhouse gases

Question 14

What evidence do you have to support this?

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Atmospheric carbon dioxide levels over time

Carbon dioxide is a greenhouse gas that is directly affected by human activities.

The amount of carbon dioxide in the atmosphere in modern times has been measured accurately since 1958. Charles Keeling measured the atmospheric concentration of CO2 at the top of Mauna Loa on the Big Island of Hawai'i.

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The curve showing the amount of atmospheric carbon dioxide is also known as a Keeling curve.

Monthly mean atmospheric carbon dioxide level at Mauna Loa Observatory, Hawai'i Dr. Pieter Tans, NOAA/ESRL and Dr. Ralph Keeling, Scripps Institution of Oceanography

Question 15

What are some of the causes of the carbon dioxide increase over the past 50 years?

Question 16

Why does the carbon dioxide level fluctuate during a single year (the red "wiggles" in the CO2 plot)?

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(Hint: Think about some natural reasons that carbon dioxide would increase and decrease over a yearly period.)

Historical carbon dioxide levels

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The Keeling curve only shows carbon dioxide levels for the past 50 years or so. The Earth has had an atmosphere for over 4 billion (4,000,000,000) years.

It is not until recently that humans have been able to measure carbon dioxide levels. How can we know what carbon dioxide levels were in the more distant past?

Atmospheric gases are stored in the spaces between ice crystals in the snow and ice of glaciers and ice sheets. Scientists drill holes into the ice to extract ice cores. Older layers of ice are at the bottom, with younger layers on top.

When sections of the ice are melted in the lab, scientists can measure the amount of carbon dioxide and other gases that were trapped when the ice formed. The levels of trapped gas are measured in parts per million (ppm). A measurement of 350 ppm CO2 means that for every one million (1,000,000) gas molecules, 350 of them are carbon dioxide.

Vostok Station is a Russian research station in Antarctica, near the South Pole. The graph shows the concentrations of carbon dioxide (in ppm) from an ice core sample. Note that the x-axis of the graph shows the time period over which data were collected. The most recent data were collected 0 years before present (on the left side of the graph); the farther to the right, the older the ice core measurements.

Carbon dioxide concentration (in ppm), measured from dissolved gases in the Vostok Ice Core.

Geology 101 - Introduction to Physical Geology Lab--Glaciers & Ice Age; Creative Commons Attribution 3.0 United States License CC-BY-3.0

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The data in the graph comes from the publication by Petit, J.R., J. Jouzel, D. Raynaud, N.I. Barkov, J.M. Barnola, I. Basile, M. Bender, J. Chappellaz, J. Davis, G. Delaygue, M. Delmotte, V.M. Kotlyakov, M. Legrand, V. Lipenkov, C. Lorius, L. Pepin, C. Ritz, E. Saltzman, and M. Stievenard. 1999. Climate and atmospheric history of the past 420,000 years from the Vostok Ice Core, Antarctica. Nature volume 399: pages 429-436.)

Question 17

How many years of data are available from the Vostok ice core? 50 years 50,000 years 420,000 years 4,000,000,000 years

Question 18

Temperature is related to the amount of carbon dioxide in the atmosphere. How does the temperature of 125,000 years ago compare to the temperature of 355,000 years ago? The temperature 125,000 years ago was likely

lower than 355,000 years ago. the same as 355,000 years ago. higher than 355,000 years ago.

Question 19 Explain your answer.

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Question 20



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Question 21


Module 3 Sources, Sinks, and Feedbacks This is the third activity in the High-Adventure Science climate unit.

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Explore the relationships between ocean surface temperature and levels of atmospheric carbon dioxide and water vapor.

Carbon cycling in the Earth system

Carbon dioxide is constantly being added to the atmosphere through both geological and biological processes. As rocks are weathered, carbon dioxide is released. Living organisms release carbon dioxide through respiration, and when they die, they release carbon dioxide as they decompose. Extra carbon dioxide is released when materials are burned.

With all of this carbon dioxide being added, why isn't the CO2 level in the atmosphere much higher?

Like water and other substances on Earth, the carbon in carbon dioxide is recycled. This means that the carbon is neither created nor destroyed but moves between various reservoirs, or storage spaces, on Earth.

The flow chart shows the movement of carbon dioxide between Earth's carbon reservoirs. For example, carbon dioxide in the atmosphere can come from the land and the ocean. It can also be stored in the land and the ocean.

Follow the arrows in the flow chart to see how carbon dioxide moves between different reservoirs.

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Question 1

Which statement is true about the CO2 cycle? Reservoirs add more carbon dioxide to the environment than they remove. Carbon dioxide travels through the environment in a single direction. Carbon dioxide is constantly moving throughout the environment. When carbon dioxide enters a reservoir, it no longer cycles.

Question 2

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Is there a reservoir that serves only to take in carbon dioxide? Explain your reasoning.

Carbon dioxide: solubility in the ocean

The ocean has many substances dissolved in it, including salt. If you try to dissolve salt in a glass of water, you'll find that more salt dissolves in the water when the water is warmer. The solubility of salt in water – how easy it is to dissolve salt in water – is affected by temperature.

The solubility of gases is also affected by temperature. How does the solubility of a gas change with temperature?

The picture shows the model you'll use to answer this question. It shows interactions between Earth's land, ocean, and atmosphere.

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Screenshot of ocean model

Question 3

Use the picture of the model to make a prediction about the effect that temperature will have on the ability of CO2 to dissolve in the ocean. Will higher temperatures increase or decrease CO2 solubility?

increase (more carbon dioxide will dissolve) decrease (less carbon dioxide will dissolve)

Question 4 Explain your prediction

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Changing ocean temperature

Use the temperature slider below the model to increase and decrease the temperature of the ocean. The temperature of the ocean is shown with a blue line; you're actually changing the temperature of the planet with this slider. Notice that the ocean temperature lags behind the temperature slider.

Watch the graphs to see what happens to the level of CO2 in the air and oceans when the temperature changes.

Go to bit.ly/changingocean

Use the simulation to answer questions 5-10.

Question 5

How does the water temperature affect the amount of carbon dioxide that can dissolve in the ocean?

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Question 6

Which statement best describes the relationship between temperature and solubility of carbon dioxide in the ocean? When Earth's ocean temperature is higher,

less carbon dioxide can be dissolved in the ocean. more carbon dioxide can be dissolved in the ocean. there is no effect on the amount of carbon dioxide that can dissolve.

Question 7#7

Of course, in the real world, we cannot just magically change the temperature of the Earth with a slider.

What is the relationship between atmospheric CO2 levels and its absorption by the ocean?

Question 8

Explain your answer

Question 9



1 2 3 4 5

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Question 10


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Water vapor: a powerful greenhouse gas

In the previous models, you saw that carbon dioxide traps infrared radiation in Earth's atmosphere and that temperature increases with increasing carbon dioxide concentration. The actual temperature increase on Earth is greater than what would be expected if only carbon dioxide levels were taken into account.

What is missing from the model?

In the last model, you learned that oceans play a role as a reservoir for carbon dioxide, but oceans play more than one role. In this model, you will explore the relationship between temperature and water vapor levels. Experiment with the temperature slider below the model.

Go to bit.ly/changingocean Use the model to answer questions 11-15.

Question 11

What is the relationship between water vapor and temperature?

Question 12

Water is a greenhouse gas. What do you think will happen to the temperature when the amount of water vapor increases?

Temperature will increase. Temperature will decrease. There will be no effect on temperature.

Question 13

Explain your answer

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Question 14



1 2 3 4 5

Question 15


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Combining the effects of carbon dioxide and water vapor

In previous models, you used a temperature slider to set the temperature. While this helped you to figure out the relationships between temperature, carbon dioxide uptake by the ocean, and the amount of water vapor in the atmosphere, it's not very realistic.

This model shows all of these relationships interacting with each other. Just as in real life, the only factor that you can control is the amount of CO2 emissions. Use the Human Emissions slider to change the amount of carbon dioxide in the atmosphere. Watch the graphs to see how the temperature and level of water vapor change as carbon dioxide levels change.

The human emission slider controls how much carbon dioxide comes out of the factory. Zero percent (0%) means that there are no human emissions. One hundred percent (100%) means that human emissions are the same as in the year 2010. Two hundred percent (200%) means that human emissions are double the 2010 level.

Go to bit.ly/co2watervapor

Use the model to answer questions 16-21

Question 16uestion #16

How does the level of carbon dioxide affect the level of water vapor in the atmosphere?

Increased levels of carbon dioxide ________ levels of atmospheric water vapor.

increase

decrease

do not affect

Question 17

Explain your answer

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Question 18ion #18

What happens to the temperature when the CO2 level increases in this model?

The temperature increases.

The temperature decreases.

The temperature stays the same.

Question 19

Explain your answer.

Question 20



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Question 21


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Multiple factors

What you saw in the last model is called positive feedback. When there is a change in the system, the change gets amplified by further changes.

One example of positive feedback is in studying to get good grades in school. When you study hard, you get better grades. The better grades motivate you to study more, and your grades get even better. The more you study, the better your grades get.

A simple feedback loop

Question 22

Describe a positive feedback system that affects Earth's temperature.

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Question 23 So far, the models have only shown increasing temperatures. However, obviously, since Earth has had ice ages in the past, temperatures do not only increase. What kinds of things could decrease Earth's temperature?

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Module 4 Feedbacks of Ice and Clouds This is the fourth activity in the High-Adventure Science climate unit.

Explore how light-colored surfaces, such as snow, ice, and some clouds, have a cooling effect on Earth's temperature.

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Ice on Earth's surface

While Earth's temperature is dependent on the greenhouse effect in the atmosphere, the amount of the Sun's energy retained by Earth is strongly dependent on how much energy is reflected off Earth's surfaces.

Albedo describes how much sunlight is reflected back into space without being absorbed by the surface. Albedo varies greatly depending on the type of surface the sunlight hits – land, water, ice, snow, or clouds. Understanding global albedo effects is critical to predicting global temperature changes.

You can explore albedo in the model by changing the amount of ice covering the surface.

Go to bit.ly/earthssurface

Use the model to answer questions 1-3.

Question 1 What happens when energy from the Sun encounters a white surface (ice or snow)? The energy is

reflected off the surface and leaves the atmosphere. reflected off the surface and trapped in the atmosphere. absorbed by the surface and stored in the land and ocean. absorbed by the surface, radiating heat into the atmosphere.

Question 2

Describe how changes in the amount of ice covering Earth's surface can affect Earth's temperature.

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Question 3 Currently, about 10% of Earth is covered with ice year-round. If this ice melts, what could happen to Earth's temperature?

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Clouds

You can feel the difference in the temperature between a cloudy day and a sunny day. You can also feel the difference in temperature between a clear winter night and a cloudy winter night. Clouds affect the temperature of Earth's atmosphere and surface.

How clouds affect temperature is a balance between how much sunlight is reflected away from Earth's surface (a cooling effect) and how much outgoing infrared radiation is absorbed and re-radiated into the atmosphere (a warming effect).

Use the Add Cloud and Subtract Cloud buttons to change the number of clouds in the Earth system model.

Go to bit.ly/cloudmodel1

Use the model to answer questions 4-6

Question 4

In this model, how do the changes in cloud cover affect Earth's temperature?

Question 5

How do energy packets (solar radiation and infrared radiation) interact with the clouds to cool the planet?

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Question 6 In this model, clouds caused the temperature to decrease. This is called negative feedback, where a stimulus (heating) results in a feedback (evaporation of water into the atmosphere, where it forms clouds) that counteracts the stimulus (cooling effect). How is this different from the positive feedback relationship of water vapor and temperature?

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Melting glaciers

Albedo is the property of a surface that determines how much sunlight is reflected or absorbed. In several places around the world, glacial ice is retreating.

The pictures show Bear Glacier in Alaska. The first photo was taken in 1909. The second photo was taken in 2005. Over 96 years, Bear Glacier retreated, leaving behind the meadow seen in the lower photo.

Question 7 Which photograph shows the land being less able to reflect incoming solar radiation (having a lower albedo)?

the 1909 photograph the 2005 photograph

Bear Glacier in Alaska, USA. Credit: National Snow & Ice Data Center. Citation: Grant, Ulysses Sherman. 1909 Bear Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center/World Data Center for Glaciology. Digital media. (http://nsidc.org/cgi-bin/gpd_deliver_jpg.pl?bear1909072002) Citation: Molnia, Bruce F. 2005 Bear Glacier: From the Glacier Photograph Collection. Boulder, Colorado USA: National Snow and Ice Data Center/World Data Center for Glaciology. Digital media. (http://nsidc.org/cgi-bin/gpd_deliver_jpg.pl?bear2005000003)

Question 8

Explain your answer

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Arctic sea ice

The graph shows the coverage, in millions of square kilometers, of Arctic sea ice from 1978 to 2010. Points in black show the ice coverage in July of each year. The blue line shows the yearly average ice coverage.

Question 9 How might the trend shown in the graph affect Earth's temperature in the year 2100?

It will increase Earth's temperature. It will decrease Earth's temperature. There will be no effect on Earth's temperature.

Question 10

Explain your answer

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Question 11



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Question 12


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Feedback: positive or negative?

Question 13

Is the melting of Arctic ice an example of positive feedback or negative feedback?

positive feedback negative feedback

Question 14

Explain your answer.

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Clouds: cooling or warming?

Scientists do not completely understand the effects of clouds on global temperature. As the planet warms, more water evaporates. When there is more water vapor in the air, more clouds can form. The high albedo of a fluffy white cloud top reflects sunlight into space, resulting in a cooling effect on Earth's surface. Clouds of all types reflect solar radiation back into space, but different clouds vary in their ability to

Clouds from an airplane window Credit: Sarah J. Pryputniewicz

absorb the outgoing radiation from Earth. For example, scientists think that high thin clouds are better at preventing infrared radiation from leaving the atmosphere. Low clouds are normally better at reflecting solar radiation back into space, which produces a cooling effect, but they can also reflect some infrared radiation back to Earth. This explains why a cloudy winter night is usually much warmer than a clear winter night. Question 15 Based on this information, how is the model both a good and a poor representation of the Earth system?

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Module 5 Using Models to Make Predictions This is the fifth activity in the High-Adventure Science climate unit.

Explore how solar radiation, Earth's surface and oceans, and greenhouse gases interact to cause global warming. Change variables to determine how much greenhouse gas emissions might need to fall to mitigate the temperature increase.

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Complex climate models

As you have seen, studying climate change involves understanding many different factors and how they interact in the complicated Earth system. Earth's climates are fueled by solar energy and complex interactions between the atmosphere, land, oceans, and living things, including humans.

Our best hope of understanding how the global temperature

The figure illustrates the development of comprehensive climate models over the last 25 years, showing how different components are first developed separately and later coupled together. Credit: Intergovernmental panel on Climate Change, Third Assessment Report, Technical Summary of Working Group I Report, 2001 (http://www.usgcrp.gov/usgcrp/images/ocp2003/ocpfy2003-fig3-4.htm)

changes over time, and how we may be affecting it, lies in mathematical climate models that scientists have developed over the past 50 years. Climate models are some of the most complex models in all fields of science, and they have already proven to be useful in simulating past climates.

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Time lags in temperature changes

You may have noticed that the temperature changed pretty quickly after you changed the carbon dioxide levels.

In the real world, there is a lag between increased carbon dioxide levels and temperature increases.

Geochemical cycle of carbon dioxide Credit: (http://my.opera.com/nielsol/blog/2009/01/11/nutrient-cycles-or-geochemical-cycles) Photos from Sarah J. Pryputniewicz

Question 1

Why is there a lag between changes in CO2 levels and temperature?

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(Hint: Remember that there are many reservoirs for carbon dioxide. Where can carbon dioxide be stored when the temperature is low?)

Meet a climate scientist: Mark Chandler

You have used many different models in this unit, just as climate scientists use models to better predict what will happen in the future.

How do scientists' models differ from the models you have used? How do scientists use their models?

The Earth system is very complex. How can you tell that the models are even valid? Read below or go to bit.ly/climatescientist1 Mark Chandler is a climate scientist at the NASA Goddard Institute for Space Sciences at Columbia University. In the video, he discusses how climate scientists use mathematical climate models to reproduce past climates.

Dr. Chandler works on modeling paleoclimates – climates from millions of years ago. He uses computers to run mathematical models of past climates. The computer programs he uses show the results of the mathematical computations visually so he can see where and how Earth's climates changed in the past.

As computers get faster, scientists are able to make better climate models. Not very long ago, weather forecasts were rarely accurate beyond a day. With faster computers, weather forecasters were able to consider many more factors, and now seven-day forecasts are pretty accurate, most of the time.

The same computing speed that has brought better weather forecasting is also bringing better climate modeling. More factors can be considered at the same time, making the models more likely to be accurate

Question 2

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Are models necessary to understand climate change? yes no

Question 3 Explain your answer

Question 4 How can you (and scientists) tell that a model is good? What kinds of tests can you run to assess the validity of a model?

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Societal effects

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Having used our models, what do they tell you about how Earth's temperature might change in years to come?

Scientists use climate models to make predictions. They set up different tests that look at predicted future emissions of greenhouse gases. They build models that consider expected changes in emissions and fossil fuel usage to try to better predict the effects of humans' actions on temperature.

These factors contribute to some of the uncertainty in climate predictions. Despite

the uncertainties, all scientific models show that Earth will warm in the next century.

Faced with warnings, the public's natural response is to ask scientists for definitive guidance. Scientists can not say exactly what is going to happen in every region of the world at a specific time, but they can tell you about trends.

It is not a scientist's job to find solutions to problems. A scientist's job is to learn how the system works. It is the job of society to be well-educated about the science so that they can make informed decisions to solve problems.

The Earth system is complex, and there is still much that is not known. There are so many different factors that influence Earth's temperature, but the models are getting better at simulating past climates. The science will always be incomplete; waiting for absolute certainty would mean waiting forever.

Question 5

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How can scientists be sure that Earth is getting warmer when they are not completely certain about what is going to happen to Earth's temperature in the future?

Millions of years of data

Earth has been much warmer in the past than it is today. The graph shows the temperature change over the past 542 million years.

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Note that the time scale of the graph changes for the different periods. The data from long ago is much more compressed than the more recent data.

Some of the temperature data is from direct measurements, but those could only be done since humans used thermometers (only about the past 200 years). Some of the data (from about 500,000 years ago) comes from the Vostok ice cores. You saw this data in earlier activities.

However, when Earth was warmer, there was no ice. Scientists cannot measure the dissolved gases in ice that is not there, so they have used other means to infer past temperatures.

The earliest temperature data is inferred from sediment core data. Scientists use sediment cores much as they use ice cores to get data about the past. The sediment cores suggest that the global temperature was much higher 50 million years ago – approximately 6°C warmer than today!

Even with data showing that Earth was far warmer before humans even existed, scientists are still confident that humans are contributing to the current warming trend.

Question 6

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Based on all of what you have learned from this module, how can scientists look at 542 million years of temperature data (in the graph) and still be confident that humans are contributing to the current warming trend?

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How much reduction?

The models in this module are much simpler than the ones scientists use because we have included only a few of the variables. But we can still use these models to test our ideas, the same way scientists do.

The highest priority issue facing climate modelers today is determining the effect of humans on Earth's temperature.

Change the human emissions slider to determine how much humans might need to change their CO2 emissions (compared to 2010 levels) to reduce the global temperature.

Go to bit.ly/co2reduction

Use the model to answer question 7-11

Question 7

How much did you need to change the human emissions to reduce the average global temperature in the model?

0-25% 25-50% 50%-75% 100% (to zero human emissions)

Question 8 Explain how reduction in human emissions can cause a temperature decline. In your explanation, include as many factors as possible.

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Question 9



1 2 3 4 5

Question 10

Explain what influenced

Question 11

What additional factors would you like to add to the model to be able to make a better prediction of the impact of a reduction of human emissions on the global temperature?

ASSESSMENT

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Imagine you are the President of the United States and delivering a speech to the country on the important issue of climate change. The goal of the speech is to persuade Americans, both individuals and companies, to make changes that will help solve the climate change problem. You must include scientific data to support your claims.

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