EarthLabs > Climate and the Carbon Cycle: Unit Overview > Lab 3. Carbon and the Atmosphere: My Life as a Greenhouse Gas > 3B: My Life's Story

Carbon In the Atmosphere - My Life as a Greenhouse Gas

Part B: Carbon Dioxide - My Life's Story

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 it own set of "fingerprints." These fingerprints serve as clues to past climates and possibly to future climates.

Consider the graph on the right. (click to enlarge). The graph shows "fingerprints" of carbon dioxide and temperature of the past six ice ages that have been revealed from ice cores drilled in Vostok, Antarctica.


Look at the various elements of the graph. The red lines represent changes in temperature over time and the blue lines represent changes in carbon dioxide over time. The peaks of carbon dioxide indicate interglacial periods. Do the "fingerprints" in this graph tell you a story of carbon dioxide and temperature over the past 600,000 years? With your partner or group, identify at least two elements of the story this graph tells you. Share your story elements with the class.

Next, listen to geoscientist, Dr. Richard Alley, explain the relationship between ice core carbon dioxide data and ice core temperature data in CO2 in the Ice Core Record Then, use information from the graph and the video to answer the Checking In and Stop and Think questions below.

Checking In

  1. Are Ice ages correlated with lower amounts of carbon dioxide (CO2) or higher amounts of CO2?
  2. From 600,000 years ago to 100,000 years ago, what was the highest concentration of carbon dioxide(ppm)

Stop and Think

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

The Keeling Curve: Is our atmosphere changing?

Consider the graph below of measurements of atmospheric carbon dioxide measured at Mauna Loa, Hawaii. Sometimes called the Keeling Curve, after atmospheric scientist Dr. Charles Keeling, this graph represents the longest running global atmospheric carbon dioxide data on record and is one of the most recognized iconic graphs in science. In the late 1950s, Dr. Keeling started measuring carbon dioxide levels on top of the Mauna Loa volcano on the Island of Hawaii in the Pacific Ocean. He chose this location because he wanted to take measurements far away from urban areas that are emitting man-made carbon dioxide into the atmosphere. Because winds and convection currents move carbon dioxide around Earth's atmosphere, it was possible for him to take global measurements of CO2.

Examine Keeling's data on the graph below, and answer the Checking In questions that follow.

  • Carbon Dioxide concentration in measured in parts per million per volume of air (ppmv)
  • The squiggly grey lines represent seasonal variation in carbon dioxide and are illustrated in the Annual Cycle box inset in the lower right of the graph.
  • The peaks are when plants are more releasing more carbon dioxide by respiration than is being taken in by photosynthesis. This happens during the winter months when deciduous trees have lost their leaves and thus cannot photosynthesis. The troughs (dips) are when more carbon dioxide is taken out of the atmosphere by trees through photosynthesis. By this time, Spring has arrived and trees have produced their leaves again. You can see this visualized on a NASA video Photosynthesis and the Keeling Curve
  • The red line represents a moving average of all the variations in the data. A moving average, also called a running average, is commonly used with time series data to smooth out short-term fluctuations and highlight longer-term trends or cycles. Batting averages in baseball is a common example of a running average.

Checking In

  1. According to the Keeling curve, how much did atmospheric carbon dioxide increase by from 1958 to 2009?

The Keeling data: Is it enough evidence to draw conclusions about a changing atmosphere on a global scale?


The Keeling Curve measurement of atmospheric CO2 is taken from the top of the Mauna Loa volcano in the Hawaiian Islands. Is this one dataset, taken from only one location in the world, enough for scientists to claim with confidence that the levels of global atmospheric CO2 are increasing? Why or why not?

When trying to understand complex systems, such as the carbon cycle or the Earth System, scientists will often compare multiple data sets to identify possible relationships and trends. When other scientists first observed Dr. Keeling's CO2 data, they immediately looked for ways to confirm the data. Would they see the same trend in increasing atmospheric CO2 if they collected CO2 measurements in different locations and used different collection methods?

Interactive Atmospheric Data Visualization (IADV). NOAA. Click to enlarge.

You may find the answer to this important question by usingCarbonTracker, a program developed by The Earth System Research Laboratory (ESRL) in Boulder, Colorado and operated by the National Oceanic and Atmospheric Administration(NOAA). ESRL studies processes that affect the atmosphere, air quality, and weather and climate. ESRL's CarbonTracker program collects all the data from greenhouse gas measurements taken from around the world and puts it into the Interactive Atmospheric Data Visualization(IADV) database that scientists and non-scientists can access at any time. Open Carbon Tracker: Interactive Atmospheric Data Visualization(IADV)Tool and and spend some time exploring to see what type of information is available.

When you are finished exploring, answer the Checking In question below and begin your research task.

1. Explore the interactivity of the IADV Carbon Tracker program. . Move your cursor over the measurement sampling sites. What information pops up? What do the red, orange and yellow dots and the blue squares on the map represent?

2. Find the the Mauna Loa site. Make note of the following information that pops up:

  • What is the latitude and longitude of the Mauna Loa measurement site?
  • What is the elevation? (masl = meters above sea level)
  • Look for the carbon cycle gas measurements that they measure at Mauna Loa. What types of measurements do they take (tower, airborne flask, surface flasks, in-situ ).
  • Are the measurements taken from land, boat or plane?

3. Next, explore other measurement sites? How do they compare to Mauna Loa?

4. Drag the map from left to right or right to left to target particular countries or area of the world.

5. Zoom in to a particular country or area of the world. What measurement site is closest to where you live? What type of data does this site collect?

6. Go back to the Mauna Loa site.

7. Find the "Program" Tab above the map. Open that tab and Click on "Carbon Cycle Gases." This action will allow you to see only those measurement sites that collect carbon cycle gas data.

8. Next, move over to the menu to the left of the map. Click on "Carbon Cycle Gases" and then click on "Time Series." This will bring you to the Keeling CO2 Data from Mauna Loa. You should see an image that looks like the image on the right.

  • Parameters - carbon dioxide (CO2)
  • Data Type - Choose Flask or In-Situ. Many sites will only have one type. Click "Submit" if you change from one to another
  • Date Frequency - Ignore and leave at "discrete"
  • Time span -Choose "All" This will give you a graph of all the data collected to date. If you would like to explore shorter data sets, you can choose "start year" and "end year" and click "Submit" to see the graph.

Congratulations! Your exploration is now complete and you should be ready to start your research task. Before you begin, answer the Checking In question below and then begin your task.

Checking In

  1. When you explored the Mauna Loa measurement site on CarbonTracker, you were asked to keep notes on the information available to you. Use those notes to answer the following question. Which of the following represents available CO2 data from the Mauna Loa site? Check all that apply

Use Carbon Tracker and begin your own research

Your research question:
The Keeling Curve CO2 data indicates that the amount of carbon dioxide in the atmosphere has been increasing at least since 1958, the first time atmospheric carbon dioxide was measured at Mauna Loa. Are the same trends in atmospheric CO2 observed in other measurements taken around the world?

Your research task:
Use the CarbonTracker IADV to answer the research question above. Examine carbon dioxide time series data from at least three sampling sites around the world taken. Describe the overall trends of CO2 at each site. Then, compare CO2trends from these sampling sites with the Keeling CO2data from Mauna Loa. Note: The yellow dots represent sampling stations no longer collecting data and should not be used in your investigation.

Choose a CO2measurement variable:
In your exploration of the CarbonTracher IADV site, you learned that there are many CO2 measurement variables you can explore. You may choose one variable (example: measurements taken on land) or you may decide to compare variables (example: measurements taken on boats versus on land). Here are some examples of variables:

When you have done your research, compare the graphs and data from your CO2 sampling sites to each other and to the Keeling Curve Mauna Loa CO2 data and graph.


  • With your partner or group, answer the research question. Do the data trends observed at your sampling sites support the same upward trend observed in Keeling curve CO2 data from Mauna Loa? What's your evidence?
  • Next, share your results with the class. Do class results support or refute Keeling Curve CO2 data? What's the evidence? Are the data trends across the class exactly the same as each other or are there differences? What might account for those differences?
  • Why is it important to make multiple measurements of CO2 and other gases other than just at Mauna Loa?

Putting it all together: Temperature, CO2, the Industrial Revolution, and Fossil Fuels.

Scientists claim that CO2 levels have increased since the Industrial Revolution and that this is due primarily to the burning of fossil fuels. Furthermore, scientists claim that increasing levels of CO2 in the atmosphere are amplifying the greenhouse effect, leading to a warmer atmosphere. What's the data that supports these scientific claims?

Comparing multiple data sets can sometimes tell a more complete story than looking at one single data set at a time. Because measurements of atmospheric CO2 only began in 1958 at Mauna Loa, scientists needed to find atmospheric CO2 data and temperature data that began with the American Industrial Revolution era. Luckily, as you have learned from Dr. Richard Alley in a previous video, the CO2 trapped in ice cores can be used to give a "proxy" measure of the CO2 in the atmosphere at that time snow was laid down. Siple ice cores from Antarctica provide this CO2 data because the snow in Siple ice cores were laid down approximately from 1880-1950. For temperature data, scientists used atmospheric temperature measurements that have been taken since the mid- 1800's in the United States. To compare temperature and CO2 data and to look for trends in temperature and CO2 over time, scientists overlaid these three data sets on the graph on the right:

  • 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).
  • The scale on the right Y-axis indicates the global temperature. Notice that the scale is in degrees Fahrenheit, not Celsius.


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?
  • Do you think the trends in the CO2 and temperature data sets will continue? What evidence from the graph supports your claim?

What is causing the increases in CO2 and temperature you have observed in the data? Are the causes natural, man-made or both? Some people on the internet have claimed that the rise in atmospheric CO2 is due to the natural process of volcanic outgassing. How do scientists know where the extra CO2 is coming from? Listen to geoscientist Dr. Richard Alley explain the science behind this very important question in the video It's Us

Before you watch, create a 3-column table with the following headings:

As you watch the video, write careful notes in your table. When you have finished watching and taking notes, share your notes with the class.


A friend tells you that they do not believe that humans are causing the rise in atmospheric CO2. How would you explain the source of the rise of atmospheric CO2to them?

Stop and Think

2. Describe the overall trend in atmospheric CO2 and temperature since the 1880's.

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

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