Arctic (Still ! ) Traps 25 % of World’s Carbon
Tuesday, 20. October 2009, 08:39:10
The arctic could potentially alter the Earth’s climate by becoming a possible source of global atmospheric carbon dioxide. The arctic now traps or absorbs up to 25 percent of this gas but climate change could alter that amount, according to a study published in the November issue of Ecological Monographs.
Carbon generally enters the oceans and land masses of the Arctic from the atmosphere and largely accumulates in permafrost. Unlike active soils, permafrost does not decompose its carbon; thus, the carbon becomes trapped in the frozen soil. Cold conditions at the surface have also slowed the rate of organic matter decomposition, allowing Arctic carbon accumulation to exceed its release. But recent warming trends could change this balance. Warmer temperatures can accelerate the rate of surface organic matter decomposition, releasing more carbon dioxide into the atmosphere. Of greater concern is that the permafrost has begun to thaw, exposing previously frozen soil to decomposition and erosion. These changes could reverse the historical role of the Arctic as a sink for carbon dioxide.
Within a few decades, the thawing permafrost could also result in a more waterlogged Arctic, a situation that could encourage the activity of methane-producing organisms. Currently, the Arctic is a substantial source of methane to the atmosphere: as much as 50 million tons of methane are released per year, in comparison to the 400 million tons of carbon dioxide the Arctic stores yearly. But methane is a very potent greenhouse gas – about 23 times more effective at trapping heat than carbon dioxide on a 100-year time scale. If the release of Arctic methane accelerates, global warming could increase at much faster rates.
Capture: This figure shows the mean extent of permafrost in the Arctic, estimated for (a) the years 1990-2000 and (b) the years 2090-2100. In (c), the estimation of loss of permafrost by 2100 is overlaid on estimations for the year 2000.
Credit: A. David McGuire
Reference:
McGuire et al. 2009.
Sensitivity of the carbon cycle in the Arctic to climate change.
November 2009, Ecological Monographs. (Vol. 79, No. 4, pp. 523-555)
doi: 10.1890/08-2025.1
Open Access
Carbon generally enters the oceans and land masses of the Arctic from the atmosphere and largely accumulates in permafrost. Unlike active soils, permafrost does not decompose its carbon; thus, the carbon becomes trapped in the frozen soil. Cold conditions at the surface have also slowed the rate of organic matter decomposition, allowing Arctic carbon accumulation to exceed its release. But recent warming trends could change this balance. Warmer temperatures can accelerate the rate of surface organic matter decomposition, releasing more carbon dioxide into the atmosphere. Of greater concern is that the permafrost has begun to thaw, exposing previously frozen soil to decomposition and erosion. These changes could reverse the historical role of the Arctic as a sink for carbon dioxide.
Within a few decades, the thawing permafrost could also result in a more waterlogged Arctic, a situation that could encourage the activity of methane-producing organisms. Currently, the Arctic is a substantial source of methane to the atmosphere: as much as 50 million tons of methane are released per year, in comparison to the 400 million tons of carbon dioxide the Arctic stores yearly. But methane is a very potent greenhouse gas – about 23 times more effective at trapping heat than carbon dioxide on a 100-year time scale. If the release of Arctic methane accelerates, global warming could increase at much faster rates.
Capture: This figure shows the mean extent of permafrost in the Arctic, estimated for (a) the years 1990-2000 and (b) the years 2090-2100. In (c), the estimation of loss of permafrost by 2100 is overlaid on estimations for the year 2000.
Credit: A. David McGuire
Reference:
McGuire et al. 2009.
Sensitivity of the carbon cycle in the Arctic to climate change.
November 2009, Ecological Monographs. (Vol. 79, No. 4, pp. 523-555)
doi: 10.1890/08-2025.1
Open Access
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http://www.esajournals.org/doi/abs/10.1890/08-2025.1
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http://www.usgs.gov/newsroom/article.asp?ID=2326&from=rss_home
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http://www.physorg.com/news174744498.html
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http://www.eurekalert.org/pub_releases/2009-10/esoa-ala101409.php
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http://www.firstscience.com/home/news/breaking-news-all-topics/arctic-now-traps-25-percent-of-world-s-carbon-but-that-could-change_72454.html
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