This report puts the human contribution of carbon to the atmosphere into the larger context of the global carbon cycle. The report focuses almost entirely on carbon dioxide (CO2), which alone is responsible for over half of the change in Earth's radiation balance. Moreover, according to the Intergovernmental Panel on Climate Change (IPCC), CO2 is the most important greenhouse gas released to the atmosphere from human activities.
Congress is considering several legislative strategies that would reduce U.S. emissions of greenhouse gases—primarily carbon dioxide (CO2)—and/or increase uptake and storage of CO2 from the atmosphere. Both approaches are viewed by many observers as critical to forestalling global climate change caused, in part, by the buildup of greenhouse gases in the atmosphere from human activities.