Carbon Cycle
Excerpted from Congressional Research Services Report RL34059
June 25, 2007
Peter Folger
Specialist in Energy Policy
Resources, Science, and Industry Division
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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.
Less than half of the total amount of CO2 released from burning fossil fuels during the past 250 years has remained in the atmosphere because two huge reservoirs for carbon — the global oceans and the land surface — take up more carbon than they release. They are net sinks for carbon. If the oceans, vegetation, and soils did not accumulate as much carbon as they do today, then the concentration of CO2 in the atmosphere would increase even more rapidly. A key issue to consider is whether these two sinks will continue to store carbon at the same rate over the next few decades. Will the sinks remove more, less, or the same amount of CO2 released from fossil fuel combustion each year? Currently, most of the total global carbon sink is referred to as the unmanaged, or background, carbon cycle. Very little carbon is removed from the atmosphere and stored, or sequestered, by deliberate action.
Congress may opt to consider how land management practices, such as afforestation, conservation tillage, and other techniques, might increase the net flux of carbon from the atmosphere to the land surface. How the ocean sink could be managed to store more carbon is unclear. Iron fertilization and deep ocean injection of CO2 are in an experimental stage, and their promise for long-term enhancement of carbon uptake by the oceans is not well understood. Congress may consider incorporating what is known about the carbon cycle into its legislative strategies, and may also evaluate whether the global carbon cycle is sufficiently well understood so that the consequences of long-term policies aimed at mitigating global climate change are fully appreciated.
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[edit] News Stories on the Carbon Cycle
In February 2009, NASA plans to launch their Orbiting Carbon Observatory (OCO) to study the earth's carbon sinks and learn more about the carbon cycle. It will circle the earth and take almost half a million measurements each day. [1]
[edit] Government Agencies and the Carbon Cycle
U.S. Department of Energy: The Department of Energy has several offices that oversee and research the effect and role of carbon emissions on the climate. These offices include the Office of Fossil Energy, and the Office of Science. The Department of Energy also runs the Oak Ridge National Laboratory. This lab is responsible for a lot of carbon research in its Carbon Dioxide Information Analysis Center.
The Office of Fossil Energy is researching two aspects of the Carbon Cycle: 1). Making systems that use fossil fuels more efficient. 2). Capturing carbon and sequestering it in various forms.
The Office of Science is focusing on ways to sequester carbon emissions. These methods include enhancing the natural terrestrial cycle, carbon sequestration in the oceans, and sequencing genomes of micro-organisms.
U.S. Carbon Cycle Science Program:
This program is a joint project between several federal agencies. These agencies include the Department of Agriculture, Department of Commerce, Department of the Interior, and the Department of Energy. Their goals are to provide a focused and coordinated research effort, and gain useful knowledge about the complexities of carbon reservoirs and the climate.
National Science Foundation -Integrated Carbon Cycle Research Program (ICCR):
The purpose of this program is to solicit competition and innovation in carbon cycle research through awarding grants to proposals that address one or all of the following foci: 1) focused process studies, (2) drainage basin and ocean margin studies, (3) global modeling and empirical studies, (4) effects of climatic change and variability on the carbon cycle, and (5) data management and development of standards and methods [2]
[edit] Recommended Reports
NARSTO Quality Systems Science Center 2007-2008 Annual Report: Summary for Policymakers
The First State of the Carbon Cycle Report:
Summary for Policymakers
Full Report
For a listing of important carbon cycle bills, click here.
To learn more about the US Carbon Cycle Science Program, click here.
[edit] Endnotes
- ↑ Jack Rosebro. "Devil in the Details: NASA Satellite Joins The Search For Carbon Sinks and Sources." Green Car Congress. January 3, 2009. http://www.greencarcongress.com/2009/01/devil-in-the-de.html
- ↑ http://www.nsf.gov/pubs/2002/nsf02016/nsf02016.htm
