PDF _ RL34059 - The Carbon Cycle: Implications for Climate Change and Congress
18-Feb-2009; Peter Folger; 13 p.

Update: Previous releases:
June 25, 2007

Abstract: Carbon is stored in the atmosphere, in the oceans, in vegetation, and in soils on the land surface. Huge quantities of carbon are actively exchanged between the atmosphere and the other storage pools of carbon. The exchange, or flux, of carbon between the atmosphere, oceans, and land surface is called the carbon cycle. In sheer magnitude, human activities contribute a relatively small amount of carbon, primarily as carbon dioxide (CO2), to the global carbon cycle. Burning fossil fuels, for example, adds less than 5% to the total amount of CO2 released from the oceans and land surface to the atmosphere each year. If humans add only a small amount of CO2 to the atmosphere each year, why is that contribution important to global climate change?

In short, the oceans, vegetation, and soils cannot consume carbon released from human activities quickly enough to stop CO2 from accumulating in the atmosphere. Humans tap the huge pool of fossil carbon for energy, and affect the global carbon cycle by transferring fossil carbon — which took millions of years to accumulate — into the atmosphere over a relatively short time span. As a result, the atmosphere contains 100 parts per million more today (380 ppm vs 280 ppm) than prior to the beginning of the industrial revolution. As the CO2 concentration grows it increases the radiative forcing (more incoming radiation energy than outgoing) of the atmosphere, warming the planet. In response, Congress is considering legislative strategies that would reduce U.S. emissions of CO2, or increase the uptake of CO2 from the atmosphere, or both.

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Topics: Climate Change, Government, Information

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