These two graphs continue to show the changes in atmospheric carbon dioxide as well as its sources. The graph on the left comes from Oak Ridge National Laboratories and shows two patterns of atmospheric carbon dioxide. On the left y-axis is total atmospheric carbon dioxide in units ppmv (parts per million volts: see Mauna Loa carbon dioxide post for discussion of units). On the right y-axis is the contribution of anthropogenic emissions in units million metric tons). It should be pointed out clearly to the students that the scale of the two y-axes are different; however, the trends of the lines are what should be presented to the students as the take home message.
The graph on the right shows another ways to present data – especially when it comes to relative amounts or percent contribution. These data come from the Energy Information Administration. (Please see date of publication and students should be made aware that these data are potentially out-dated). The story from this graph should be clear to students and the carbon dioxide from fossil fuel combustion in the largest contributor of greenhouse gases from the United States. However, not all greenhouse gases are created equal. For further discussion of this topic please see post for Greenhouse Gas Potential and Forcing.
1. These two graphs show different ways of presenting data. What are some of the advantages of each approach? Is one more dramatic than the other? When would you use the line graph and when might you use the pie-graph and can these graphs be manipulated to make certain points?
2. Students can begin to research their own carbon footprints using the following links. When done, teachers could facilitate a class discussion on the differences between the calculators and the results.
Teacher can then refer students to the following links to provide solutions in reducing carbon footprints.
Students can also analyze their opinions on global issues here: Relief in Every Window, but Global Worry Too