Methane Source
Buried basal ice from the Laurentide Ice Sheet preserved as massive ice and icy sediments in permafrost, NW Canada. (photo: Julian Murton)
The land distributed in Alaska, Northern Canada and Tibetan plateau is permafrost. The permafrost is the land that frozen continuously about 2 years, with temperatures below 0 °C. And the depth of the frozen land is about few meters to 1,500 meters. Most of the permafrost was made at last glacial maximum (LGM), 20,000 years ago. But, currently, a number of studies show that the permafrost can significantly affect the global warming.
Currently, the arcademic world estimate that about 1,700Gt of organics which contain carbon are burried in permafrost. The amount of carbon source exist in permafrost is 2 times more than atmosphere, and 3~7 times more than in Tropical forests.
But, as the ice of permafrost getting melts, the organic matters captured under the land can afftect the composition of atmosphere of the earth. This organic matters are regarded as pure energy source for next generation. this is called methane hydrate. The methane hydrate is made with the conditon in high pressure and low temperature on ancient organic matters. To satisfy this conditions, formation of methane hydrate occurs commonly in the bottom of the sea which had made after ice-age or permafrost. In such condition, methane hydrate has high energy density, and emits small amount of carbon dioxide. So it sometimes called as ‘Burnig ice’.
Methane hydrates are extremely difficult to study, and could either be an important energy source or a source of methane, a greenhouse gas that is 20 times more potent than CO2. These reasons led a Norwegian, Dutch and Chinese research team to explore the mechanical properties of this poorly understood substance. Credit: Geir Mogen, NTNU
But, methane hydrate is so unstable that it has to exist in specific condition. If methane hydrate is emitted to atmosphere in situation like ice melting which makes methane hydrate unstable, this carbon source can degradated and oxidate to carbon dioxide (CO2) or methane (CH4). Especially, methane is one of the powerful green-house gases that can cause abnormal climate like excessive green-house effect.
Pockmarks are scars on the ocean floor, an evidence of gas release. These likely appeared as the ice sheet retreated from the western part of Svalbard, and the area began to submerge in seawater again. They prove that release of methane followed the retreat of the ice sheet. Credit: Alexey Portnov/CAGE
In other words, temperature increasing caused by global warming affect ice melting and again, it increases the effect global warming. Such cycle has positive feedback on global warming, So some experts suppose that the average global temperature increases about 0.1~0.3℃ only by carbon emitted from melting permafrosts. This is a serious change on earth compare to increase of temperature through last 100 years (1906-2005). According to IPCC, if global warming progress in current trend, in 2100 the average temperature of earth would increased by 4 ℃ from now on.
Schematic sketch (not to scale) depicting the Arctic methane feedback. Pronounced regional warming increases methane emissions, which strengthen the greenhouse effect and warm the surface. The warming, in turn, triggers additional emissions. Figure modified from Ruppel and Noserale D (2012).
Refrence
http://news.dongascience.com/PHP/NewsView.phpkisaid=20120423200002296026&classcode=011404
-http://blog.naver.com/jjy0501/220607858209
-http://www.dongascience.com/news/view/8560
-http://news.naver.com/main/read.nhn?mode=LSD&mid=sec&sid1=104&oid=003&aid=0004512752
-http://news.sbs.co.kr/news/endPage.do?news_id=N1002698699&plink=ORI&cooper=NAVER