Carbon In the Atmosphere - My Life as a Greenhouse Gas
Part B: Carbon Dioxide - My Life's Story
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.
DiscussionLook 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.
Stop and Think1. Describe the relationship between carbon dioxide, temperature and ice ages.
The Keeling Curve: Is our atmosphere changing?
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.
The Keeling data: Is it enough evidence to draw conclusions about a changing atmosphere on a global scale?
DiscussionThe 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?
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.
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.
- 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.
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:
- Latitude and longitude: (ex) polar, temperate or tropical latitudes
- Type of measurement – (ex) tower, surface flask, in-situ
- Where measurements are taken – (ex) on land, boat, or plane
- Elevation (masl = meters above sea level)
- 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.
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:
- Global long term temperature data 1880-2006 (Blue lines)
- Ice core CO2 data from the Siple Dome ice core, Antarctica 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).
- The scale on the right Y-axis indicates the global temperature. Notice that the scale is in degrees Fahrenheit, not Celsius.
DiscussionWith 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:
- Type of Cause.
- Evidence for this being a major cause of rising CO2 levels.
- Evidence against this being a major cause of rising CO2 levels.
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.
DiscussionA 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.