- Yedoma
Yedoma is an organic-rich (about 2%carbon by mass)
Pleistocene -ageloess permafrost with ice content of 50–90% by volume [K. M. Walter, S. A. Zimov, J. P. Chanton, D. Verbyla & F. S. Chapin III, "Methane bubbling from Siberian thaw lakes as a positive feedback to climate warming", Nature, 443, 71-75, 2006] . The amount ofcarbon trapped in this type of permafrost is much more prevalent than originally thought and may be about 500 GT, that is almost 100 times the amount of carbon released into the air each year by the burning offossil fuel s [http://www.thewe.cc/weplanet/news/arctic/permafrost_melting.htm Scientists Find New Global Warming "Time Bomb"] . Melting yedoma is a significant source of atmosphericmethane (about 4 Tg of CH4 per year).Yedoma currently occupies an area of more than one million square kilometers in northeast
Siberia , and in many regions is tens of meters thick. During theLast Glacial Maximum , when the global sea level was 120 m lower than that of today, similar deposits covered substantial areas of the exposed northeast Eurasiancontinental shelves. At the end of lastice age , at thePleistocene -Holocene transition, thawing yedoma and the resultingthermokarst lakes may have produced 33 to 87% of the high-latitude increase in atmosphericmethane concentration [K. M. Walter, M. E. Edwards, G. Grosse, S. A. Zimov, F. S. Chapin III "Thermokarst Lakes as a Source of Atmospheric CH4 During the Last Deglaciation" Science, 318, 633-636, 2007] .References
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