The three main gases that trap heat in earths atmosphere are choose... , methane, and water vapor.

View the image below. On which planet would you like to live?

With with a partner or group, compare the atmospheres of Mars, Earth, and Venus in the image above and then use the following questions to guide your discussion.

• On which planet would it be possible for you to live? Why?
• Which planet would have a greater diversity of life (biodiversity)? Why?
• What relationship, if any, do you see between the amounts of carbon dioxide and the temperature in these three atmospheres?
• You have probably heard about the "greenhouse effect" in previous science classes or in the media. Based on your current understanding of the greenhouse effect, which planet do you think has the strongest greenhouse effect? Which has the weakest? Why?

Greenhouse gases regulate the temperature of Earth's lower atmosphere via the greenhouse effect

Scientists now know the comfortable climate we enjoy today on Earth is due to a natural greenhouse effect natural phenomenon that warms the temperature of Earth's surface and lower atmosphere because greenhouse gases absorb and emit infrared radiation that would otherwise escape to outer space. Some of this emitted infrared is returned to Earth's surface regulated by greenhouse gases atmospheric gases that warm the temperature of Earth's lower atmosphere by absorbing and emitting infrared radiation that would otherwise escape to outer space; includes carbon dioxide, methane, water vapor, ozone, nitrous oxide and CFCs.. Carbon dioxide (CO2) and methane (CH4) are two powerful greenhouse gases produced by the carbon cycle.

In this section, you will learn how the carbon cycle regulates Earth's climate through the greenhouse effect. Without a greenhouse effect, Earth's climate would be cold like Mars, with an average surface temperature surface of about -15 degrees Celsius (5 degrees Fahrenheit). With a temperature so cold, all water on Earth would freeze and life as we know it would not exist. With a very strong greenhouse effect, Earth's climate could be more like that of Venus where temperatures are around 420 degrees Celsius (788 degrees Fahrenheit). Most living organisms we are familiar with could not exist in a climate this hot. Examine the image of Earth's greenhouse effect pictured on the right and then watch the NASA video below. Make note of how each of the following contributes to Earth's greenhouse effect:

https://www.youtube.com/watch?v=ZzCA60WnoMk&feature=youtu.be

NOTE: If the video does not load, click Greenhouse Effect

With a partner or the class, discuss the following:

• Describe how the greenhouse gases CO2 and H2O contribute to Earth's greenhouse effect.
• What if no infrared radiation was re-emitted back to Earth's surface by greenhouse gases? Do you think Earth's climate would be colder, warmer or the same? Explain why you think so.

Earth's lower atmosphere (the troposphere) is comprised of greenhouse gases and non-greenhouse gases in different concentrations

As you can see in the pie graph pictured on the right, the lower atmosphere is made mostly of nitrogen(N2) and oxygen(O2) gas molecules. While both nitrogen and oxygen are important in supporting life on Earth, they are not greenhouse gases. Greenhouse gases such as carbon dioxide and water vapor comprise a very small part of the lower atmosphere and are found only in trace amounts.

Consider the table below and then answer the Checking In questions that follow.

Parts Per Million describes the concentration of one type of atmospheric gas to the concentration of other gases in the atmosphere. For example, carbon dioxide has been expressed as 397 ppm. This means that for every million molecules in the atmosphere, there are approximately 397 molecules of carbon dioxide. NOTE: The concentration of CO2 continues to rise. Check this site to get the current global concentration of CO2 in ppm: NASA Vital Signs of the Planet

Average Residence Times describes the approximate amount of time that different types of atmospheric gases spend in the atmosphere before chemically decaying or moving to another reservoir. A greenhouse gas with a long residence time has greater potential to build up to higher concentrations. This would in turn lead to more infrared being absorbed and a stronger greenhouse effect.

Variability over Time and Spatial Scales describes how the concentration of an atmospheric gas varies over time and space. For example, concentrations of nitrogen and oxygen remain fairly constant around the globe. In contrast, the concentration of CO2 varies over both time and space. For example, in the northern hemisphere (a large hemispheric spatial scale), the concentration of CO2 varies from season to season. H2O vapor in the atmosphere is highly variable because it is part of the water cycle. Some days and regions are dry whereas others have quite a bit of rain.

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The carbon cycle has changed over Earth's history

Imagine if fossils didn't exist. How would we know that dinosaurs, woolly mammoths and other long-extinct creatures once roamed the Earth and swam in our oceans. Like fossils, carbon dioxide has left its own set of "clues" about past atmospheres and climates in ice cores a core sample that is typically removed from an ice sheet, most commonly from the polar ice caps of Antarctica, Greenland or from high mountain glaciers elsewhere. from Antarctica.

Take several minutes to examine the graph pictured above and then answer the Checking In questions below. The carbon dioxide data (blue lines) and temperature data (red lines) are taken from ice cores drilled in Vostok Station Antarctica. The peaks of carbon dioxide indicate interglacialwarm period within a glacial age periods and the troughs represent ice ages any geological period in which long-term cooling takes place and ice sheets and glaciers exist. (also called glacial ages).

The ice core CO2 and temperature data you just explored raises some interesting, more complex questions. Read the questions below and be prepared to discuss them after watching the movie below. Take notes, pausing and replaying as needed. NOTE: Your teacher may decide to assign each group specific questions to take notes on.

• How are ice ages and interglacial periods related to carbon dioxide and temperature? Why are ice cores critical to revealing this relationship?
• What causes ice ages to come and go?
• Does ice core data measured at Vostok reflect historic temperatures and concentrations of atm CO2on a regional scale or a global scale. What is the evidence? Why is knowing the spatial scale important?
• How were changes in CO2 and temperature related to each other as Earth swung back and forth between ice ages and interglacial periods? For example, which came first- a rise in temperature or a rise in CO2?
• Were there any feedbacks operating as temperature and concentrations of CO2 changed? If so, how did they operate and at what time scale?

To help you answer these important questions, focus on the following topics as you watch the video:

Ice cores come from every place in the world where ice accumulates over time. Ice cores from the Antarctic and Greenland ice sheets are the most famous. The longest records of atmospheric CO2 in ice cores collected by scientists extends back to 800,000 years. Molecules of CO2and other gases in the atmosphere diffuse into the top layer of snow and are trapped there in ice bubbles. As new layers of snow and ice accumulate over time, a record of concentrations of atmospheric CO2 and other gases form over time revealing clues about past climates. Watch this video Ice Core Secrets Could Reveal Answers to Global Warming - Science Nation and other videos at The National Ice Core Laboratory

2: Describe the relationship between carbon dioxide, temperature and ice ages.

A slow acting geologic carbon cycle is key to reducing the concentration of atm CO2 over very long time scales (hundred thousands of years to millions of years).

As Earth swung between ice ages and interglacial periods over the past 800,000 years, the concentration of atm CO2 rose and fell with these swings. A slow-acting geological carbon cycle is responsible for reducing the concentration of atm CO2as Earth swung from interglacial periods to ice ages. Atmospheric chemistry, rain, and rock weathering worked in concert to slowly remove CO2 from the atmosphere over long time scales of hundreds of thousands of years. Watch and listen to Harvard University professor Dr. Daniel Schrag explain to high school students why the processes of Earth's geological carbon cycle is critical to the stability of Earth's climate over long time scales. As you watch the video, take notes on the following:

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3C: Keeping track of CO2 in today's atmosphere

In Lab 3B, you observed that changes in the global carbon cycle can operate at very long time scales associated with past ice ages. In this section, you will investigate recent trends in changes in atm CO2 over much shorter time scales of years to decades. First, take a few minutes to examine the graph on the right. Click to enlarge.

How does the current trend of atm CO2 since 1950 compare to atm CO2 over the past 650,000 years?

Variations and trends are important patterns that scientists look for in complex systems

Long-term time series data are important to scientists who study complex systems such as climate and the carbon cycle. Time series data taken at equal time intervals often generate important trends that help explain the behavior of a system over time. Scientists use trends to understand the past, the present and to predict the future. Long-term trends can emerge from data that is often quite variable and operates at very different time and spatial scales. You have already seen examples of this variability when you analyzed CO2 and temperature data from the Vostok ice cores.

To help you understand the difference between trend and variation, watch the video below:

Watching Earth Breathe: Seasonal changes in vegetation and CO2

Different components of a complex system such as the carbon cycle can operate over many different time scales and spatial scales. For example, NASA has detected seasonal changes in atm CO2 concentration measured by AIRS and in vegetation growth measured by another instrument on the Aqua satellite called MODIS. NASA has used the data from AIRS and MODIS to create a year long animation of these seasonal changes in CO2 and vegetation. Before you watch the NASA animation below, make note of the following:

• CO2 in the atmosphere is represented by the color orange. The deeper the orange, the greater the amount of CO2.
• Changes in vegetation growth is represented by the color green. The deeper the green, the denser the vegetation.
• You can pause the animation by clicking on the date (example SEPT 01) or by clicking pause.
• It helps to first pay careful attention to what the vegetation is doing and then pay attention to what CO2 is doing.
• Remember that vegetation and photosynthesis are linked.

With a group or with the class, discuss the following:

• What patterns in atm CO2 and vegetation over time can you observe in this animation? List all that you can.
• On what time scales are the changes in atm CO2 and vegetation changing?
• How do the spatial scales of atm CO2 and vegetation differ between the Northern Hemisphere and the Southern Hemisphere? What might account for those differences? Hint: Think about differences in land mass.
• Explain how a seasonal change in vegetation and photosynthesis can drive a seasonal change in levels of atm CO2.
• Did you observe any long-term trend(s) in concentrations of CO2 in the animation?

The Keeling Curve reveals seasonal patterns and a decadal trend in atm CO2

As the leading greenhouse gas, atm CO2 is the most closely studied and measured gas in our atmosphere. In the 1950s, the United States Air Force studied atm CO2 as part of their Cold War missile program. In 1958, regular measurements of atm CO2 began when a young geochemist named Charles Keeling collected and analyzed samples of CO2 on top of the Mauna Loa volcano on the Island of Hawaii in the Pacific Ocean. When analyzing his atm CO2 data, Dr. Keeling discovered some interesting patterns in CO2 and a worrisome trend. Watch the video below on Charles Keeling and his data. As you watch, pay attention to the pattern of variations in CO2.

Next, use the animation below to investigate Keeling's atm CO2 data in greater depth. As you go through the animation:

• Keep in mind what you have already learned about the seasonality of the carbon cycle and its relationship to vegetation and photosynthesis.
• At the end of the Animation there is a More Info screen where you will find hints to understanding Dr. Keeling's data. You can also find a link to the most recent monthly average CO2 data measured from Mauna Loa below.
• atm CO2 is measured in ppm—or parts per million per volume. Watch this visualization of 392 ppm of carbon dioxide molecules compared to nitrogen and oxygen molecules in the atmosphere to help you understand ppm.

Discuss

With a peer or group, discuss the following:

• Describe the pattern of variations that emerged from Keeling's CO2 data. Did you see these same types of variations in the NASA animation of seasonal CO2 and vegetation? Explain.
• Describe the time series trend of atm CO2measured at Mauna Loa. What does this trend "say" about the concentration of atm CO2 since 1958?
• What evidence, if any, does Keeling's data provide that the carbon chemistry of our atmosphere is changing?
• The Keeling Curve represents atm CO2 data taken from the top of the Mauna Loa volcano in the Hawaiian Islands. Because of this, some people on the Internet have claimed that Keeling's data is influenced by CO2 released from the nearby volcano. Does the rise in atm CO2concentration over Mauna Loa represent a trend only on a regional scale or on a global scale? What makes you think so?

The Keeling Curve CO2 data indicates that the amount of atm CO2measured at the Mauna Loa Observatory has been increasing since 1958, the date of the first measurement taken by Charles Keeling. Is this same trend occurring elsewhere in the world?

You may find the answer to this important question by using CarbonTracker, a program developed by The Earth System Research Laboratory (ESRL) in Boulder, Colorado and operated by the National Oceanic and Atmospheric Administration (NOAA). ESRL collects greenhouse gas measurements from participating monitoring stations around the world and inputs the data into the Interactive Atmospheric Data Visualization (IADV) CarbonTracker database tool. Scientists and non-scientists can access this database at any time.

Laboratory Investigation: Instructions

In this investigation, your group will use CarbonTracker to generate graphs of atm CO2 data measured from different sampling locations around the world. You will compare these graphs to each other and to Mauna Loa data to look for differences and similarities in trends and variations.

1. Before you begin your investigation, it is important to spend some time familiarizing yourself with the CarbonTracker tool.
   
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   1. Click on the Carbon Tracker: Interactive Atmospheric Data Visualization (IADV)Tool to explore its interactivity. NOTE: The CarbonTracker tool should open up at at the Mauna Loa site.
      • Drag the map from left to right or right to left to target particular countries or area of the world.
      • Zoom in to a particular country or area of the world. What measurement site is closest to where you live?
   2. Click on the different colored dots on the map. These dots represent sites where CO2 and other atmospheric gases are measured measurement sampling sites in the map. NOTE: When you click on a dot, the name of the measuring site will appear on the right hand part of the tool.
      • Blue dots represent major program sites measuring many variables.
      • Red dots are smaller program sites
      • Orange dots are oceanographic vessels measuring carbon cycle gases as they cruise
      • Yellow dots are inactive sites. Data is no longer being collected at these sites.
   3. Note the type of information that pops up at each measuring sampling site:
      • latitude and longitude
      • elevation (masl = meters above sea level)
      • the types of gases measured (e.g., carbon cycle gases, ozone etc)
      • how they measure the gases (e.g., tower, airborne flasks, surface flasks, in-situ)
   4. Explore the tabs under "Data Visualization>>Site Selection." These pull down tabs will help you filter and select the CO2 measuring sites you are interested in. Alternatively, you can hover your cursor on a blue, red or orange dot in a location that interests you.
      • Click on theSelect a Sampling Location from Lat or Map tab. This tab lets you pick the CO2 sampling sites that interest you.
      • Click on Programs and choose "Carbon Cycle Gases." This action will allow you to see only those measurement sites that collect carbon cycle gas data.
      • Click on Active Sites and choose "Active sites." This action will only show those locations that are actively measuring carbon cycle gases
      • Click on Pop-up Details and choose "Full." This action will display full site information you may want to use in your research.
      • Click on the Lat:Lon bar. This bar indicates the longitude and latitude of where you place your cursor.
   5. Move over to the menu on the right hand site of the tool and look under the heading "Select Measurement and Program Type."
      • Click on "Carbon Cycle Gases."
      • Then, click on "Time Series." This will bring you a new window in the tool that allows you to create data plots of atm CO2from this sampling site.
   6. Click on Parameters and choose "carbon dioxide (CO2)."
   7. Click on Data Type and choose "Flask" or "In-Situ." Many sites will only have one type. Click "Submit" if you change from one to another.
   8. Click on Data Frequency and choose "discrete." NOTE: "Discrete" may be the only choice.
   9. Click on Time span. Choosing "All" will give you a graph of all the data collected to date. If you decide to use a shorter time series (ex. ten years) you can choose "some -a subset" and then choose a "start year" and "end year."
   10. Click on "Submit" to generate a graph of the CO2 data for this site.

2. Make a 9 column table in your lab notebook with the following headings:
   • Name of monitoring station: (ex. Mauna Loa)
   • Location description (ex. country, hemisphere, ocean, top of mountain, Arctic etc.)
   • Latitude and longitude: (ex. Mauna Loa is at 19.54 N latitude; 155.5 W longitude)
   • Polar, temperate or tropical latitude
   • Type of measurement used – (ex. tower, surface flask, in-situ.)
   • How measurements are taken – (ex. on land, boat, or plane)
   • Elevation (masl = meters above sea level)
   • Time span (ex. 1960-2015)
   • How CO2 has changed (in ppm) in this time span.
3. Enter the Carbon Tracker: Interactive Atmospheric Data Visualization (IADV)Tool. Once there, use CarbonTracker to generate a graph of CO2 time series data measured at Mauna Loa. NOTE: Your teacher may decide to do this with you as a class and show the graph on a smartboard.
4. In your group, decide which three CO2 monitoring stations around the world you would like to investigate.
5. Decide the time series you will investigate for each CO2data set. NOTE: If possible, select the same time series for all of the graphs you generate. This will allow you to more easily compare trends across your graphs.
6. Use CarbonTracker to generate a CO2 time series graph for each sampling location you have chosen. NOTE: Your teacher will tell you how you will share these graphs with your group and with the entire class. For example, you can create a PDF which you can print, download, e-mail or send to a new window.
7. Within your group, compare your CO2 time series graphs to each other and to the Mauna Loa CO2 time series graph. Analyze the graphs for differences and similarities in trends and variations. Use the discussion questions below to guide your analysis.
8. Compare your graphs and your analysis with the class. NOTE: Your teacher may decide to have you do a jigsaw activity or a gallery walk. Use the post-investigation discussion questions below to guide your analysis.

• Describe the trends and variations of atm CO2 in the three sampling sites your group investigated. How do they compare with the Mauna Loa data?
• Are the data trends across the class exactly the same as each other or are there differences? What might account for those differences?
• Is the rise of CO2 concentration in the atmosphere happening on a regional scale or a global scale? What is the evidence from CarbonTracker?

Is Earth experiencing a stronger greenhouse effect? What's the evidence?

Most scientists claim that the increasing concentration of CO2 in the atmosphere is creating a stronger (or amplified) greenhouse effect leading to a warmer atmosphere. What data supports this claim? The graph pictured on the right brings three different data sets together to tell a more complete story about changes in atm CO2 and global temperatures since the Industrial Revolution began. Click to enlarge the graph on the right and carefully examine each of its three data sets as described below:

• Global long term temperature data 1880-2006 (Blue lines).
• Ice core CO2 data from the Siple Dome in Antartica, 1880-1950 (Red lines)
• Keeling Curve CO2 data taken at Mauna Loa 1958-2006 (Yellow lines)

• There are three scales on this graph, so it is important to match the correct scale with its correct data set. The time in years is the bottom scale on the x-axis.
• The scale on the left y-axis indicates the concentration of carbon dioxide in the atmosphere and is measured in parts per million per volume (ppmv). This is the same as ppm.
• The scale on the right y-axis indicates the global temperature. Notice that the scale is in degrees Fahrenheit, not Celsius.

Discuss

With a partner or a group, discuss the following and then share with the class.

• What trends do you see in these three data sets?
• What "story" does this graph tell you about the relationship between CO2 and temperature since the 1800's?
• What trends in atm CO2 and temperature have you observed thus far support or refute the claim that the greenhouse effect is amplifying? Explain why.

3: Describe the overall trend in atmospheric CO2 and temperature since the 1880s.

4: Based on the current scientific data, what is causing the increases in atmospheric CO2? Describe one piece of evidence that supports your claim.

Want to learn more about carbon in the atmosphere and the keeling Curves? Check out these resources:

• Research the latest research! New research on the carbon cycle, climate and the environment is on-going. You can use ScienceDaily and Phys.org to research recent research on greenhouse gases and climate by using combinations of the following tags: greenhouse gases, climate change, carbon cycle, Keeling Curve. Here are two examples:

Climate change caused by ocean, not just atmosphere -- ScienceDaily

Seeing carbon dioxide as a raw material rather than a waste product could lead to a more sustainable future

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