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Yedoma is an organic-rich (about 2% carbon by mass) Pleistocene-age permafrost with ice content of 50–90% by volume. The amount of carbon trapped in this type of permafrost is much more prevalent than originally thought and may be about 210 to 450 Gt, that is a multiple of the amount of carbon released into the air each year by the burning of fossil fuels. Thawing yedoma is a significant source of atmospheric methane (about 4 Tg of CH
4 per year).
The Yedoma region currently occupies an area of more than one million square kilometers from northeast Siberia to Alaska and Canada, and in many regions is tens of meters thick. During the Last Glacial Maximum, when the global sea level was 120 m lower than that of today, similar deposits covered substantial areas of the exposed northeast Eurasian continental shelves. At the end of last ice age, at the Pleistocene — Holocene transition, thawing yedoma and the resulting thermokarst lakes may have produced 33 to 87% of the high-latitude increase in atmospheric methane concentration.
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Rutter&Velichko (1997) "Quaternary of northern eurasia: Late pleistocene and holocene landscapes, stratigraphy and environments, Nat W. Rutter, editor-in-chief, Guest editors A. A. Velichko et al, Vols 41/42 July/August 1997, ISSN 1040-6182
Late Quaternary environments of Soviet Union, A.A. Velichko, engl edition Wright&Narnosky, pp176-177, University of Minnesota Publ, Longman, London 1984, ISBN 0-582-30125-4
Climate change and Arctic ecosystems: 2. Modeling, paleodata-model comparisons, and future projections, J. O. Kaplan, N. H. Bigelow et al, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 108, NO. D19, 8171, doi:10.1029/2002JD002559, 2003
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