{ "id": "RL34059", "type": "CRS Report", "typeId": "REPORTS", "number": "RL34059", "active": false, "source": "EveryCRSReport.com, University of North Texas Libraries Government Documents Department", "versions": [ { "source": "EveryCRSReport.com", "id": 344424, "date": "2009-02-18", "retrieved": "2016-04-07T02:45:39.676679", "title": "The Carbon Cycle: Implications for Climate Change and Congress", "summary": "Huge quantities of carbon are actively exchanged between the atmosphere and other storage pools, including the oceans, vegetation, and soils on the land surface. The exchange, or flux, of carbon among the atmosphere, oceans, and land surface is called the global carbon cycle. Comparatively, human activities contribute a relatively small amount of carbon, primarily as carbon dioxide (CO2), to the global carbon cycle. Despite the addition of a relatively small amount of carbon to the atmosphere, compared to natural fluxes from the oceans and land surface, the human perturbation to the carbon cycle is increasingly recognized as a main factor driving climate change over the past 50 years.\nIf humans add only a small amount of CO2 to the atmosphere each year, why is that contribution important to global climate change? The answer is that the oceans, vegetation, and soils do not take up carbon released from human activities quickly enough to prevent CO2 concentrations in the atmosphere from increasing. Humans tap the huge pool of fossil carbon for energy, and affect the global carbon cycle by transferring fossil carbon\u2014which took millions of years to accumulate underground\u2014into the atmosphere over a relatively short time span. As a result, the atmosphere contains approximately 35% more CO2 today than prior to the beginning of the industrial revolution. As the CO2 concentration grows it increases the degree to which the atmosphere traps incoming radiation from the sun, which further warms the planet.\nThe increase in atmospheric CO2 concentration is mitigated to some extent by two huge reservoirs for carbon\u2014the global oceans and the land surface\u2014which currently take up more carbon than they release. They are net sinks for carbon. 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. If the oceans, vegetation, and soils did not act as sinks, then the concentration of CO2 in the atmosphere would increase even more rapidly. \nCongress is considering legislative strategies to reduce U.S. emissions of CO2 and/or increase the uptake of CO2 from the atmosphere. Congress may also 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. Some land management practices may be eligible to receive carbon offsets in cap-and-trade legislation that is under consideration. A cap-and-trade system designed to include carbon offsets would likely need an accurate and precise accounting for the tons of carbon sequestered deliberately by land management practices. 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.\nOf additional concern is how the ocean and land surface sinks will behave over the coming decades and longer, and whether they will continue to take up more carbon than they release. The uncertainty in the future behavior of carbon sinks implies that accurately predicting the concentration of atmospheric CO2 in the future is also uncertain, even if the amount of CO2 emitted to the atmosphere could be controlled precisely.", "type": "CRS Report", "typeId": "REPORTS", "active": false, "formats": [ { "format": "HTML", "encoding": "utf-8", "url": "http://www.crs.gov/Reports/RL34059", "sha1": "4d06515c08b08fdb536ea7c7a48ea37e04a6f35e", "filename": "files/20090218_RL34059_4d06515c08b08fdb536ea7c7a48ea37e04a6f35e.html", "images": null }, { "format": "PDF", "encoding": null, "url": "http://www.crs.gov/Reports/pdf/RL34059", "sha1": "f673a0ffe284b852b8a11ffb44165b77dee1767b", "filename": "files/20090218_RL34059_f673a0ffe284b852b8a11ffb44165b77dee1767b.pdf", "images": null } ], "topics": [] }, { "source": "University of North Texas Libraries Government Documents Department", "sourceLink": "https://digital.library.unt.edu/ark:/67531/metadc463135/", "id": "RL34059_2008Mar13", "date": "2008-03-13", "retrieved": "2014-12-05T09:57:41", "title": "The Carbon Cycle: Implications for Climate Change and Congress", "summary": "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.", "type": "CRS Report", "typeId": "REPORT", "active": false, "formats": [ { "format": "PDF", "filename": "files/20080313_RL34059_79de420a0f7a988536787cd78b60978ff1ba08bc.pdf" }, { "format": "HTML", "filename": "files/20080313_RL34059_79de420a0f7a988536787cd78b60978ff1ba08bc.html" } ], "topics": [ { "source": "LIV", "id": "Carbon dioxide", "name": "Carbon dioxide" }, { "source": "LIV", "id": "Greenhouse gases", "name": "Greenhouse gases" }, { "source": "LIV", "id": "Greenhouse effect", "name": "Greenhouse effect" }, { "source": "LIV", "id": "Air pollution", "name": "Air pollution" }, { "source": "LIV", "id": "Carbon dioxide sinks", "name": "Carbon dioxide sinks" }, { "source": "LIV", "id": "Environmental policy", "name": "Environmental policy" } ] }, { "source": "University of North Texas Libraries Government Documents Department", "sourceLink": "https://digital.library.unt.edu/ark:/67531/metadc808147/", "id": "RL34059_2007Jun25", "date": "2007-06-25", "retrieved": "2016-03-19T13:57:26", "title": "The Carbon Cycle: Implications for Climate Change and Congress", "summary": null, "type": "CRS Report", "typeId": "REPORT", "active": false, "formats": [ { "format": "PDF", "filename": "files/20070625_RL34059_3ac72b51d86e337e881f04b19bbc2f79fc6a303a.pdf" }, { "format": "HTML", "filename": "files/20070625_RL34059_3ac72b51d86e337e881f04b19bbc2f79fc6a303a.html" } ], "topics": [] } ], "topics": [] }