Yedoma

Yedoma
What is it? Loess and loess-related deposits which have a particularly high ice content and a large volume of organic carbon.
Where is it found? Lena River and Kolyma River drainages of Sakha Republic, Russia, mostly north of 55 degrees.
What are the implications? This area is currently permafrost. When ice-frozen ground thaws, the loss of volume from melting ice creates depressions where water ponds. Methane emissions from these "thermokarst" lakes are a large source of methane during greenhouse warming. This may have contributed to the abrupt warming around 11,500 years ago.

Reference: Thermokarst Lakes as a Source of Atmospheric CH4 During the Last Deglaciation. K.M. Walter, M.E. Edwards, G. Grosse, S.A. Zimov, and F.S. Chapin III. Science 318:633-636 (26 October 2007).