Permafrost Thawing Below Shallow Arctic Lakes Due To Winter Climate Change

A research reveals that the thick frozen sub-layer of soil underneath the shallow arctic lakes is thawing because of the changing winter climate.

The study was published in Geophysical Research Letters, a journal of the American Geophysical Union. It was led by Christopher Arp, the lead author of the study and the research assistant professor at The University of Alaska Fairbanks (UAF) Water and Environmental Research Center and other colleagues.

Christopher Arp explained that the late winter lake ice thickness depths commonly exceeded 2 meters (6.5 feet) in northern Alaska in the 1970s. This thick ice growth helps to limit sub-lake permafrost thaw by freezing the residues solid each winter. On the other hand, he said that during winter field surveys over the last decade, the lake ice has typically only grown to 1.5 meters (5 feet) thick and has been as thin as 1.2 meters (4 feet).

The lake ice is heading to sub-lake permafrost thaw now. The rising temperatures in the lakebeds make the permafrost thaw than beneath the surrounding dry land. The lakes may enfold 20 to 40 percent of the landscape in vast areas of Arctic lowlands.

The main reason for the warming of the shallow lakebed temperatures and the thawing of the permafrost is caused by changes in the winter climate. The findings of the study are significant for conducting winter fieldwork in the Arctic.

Vladimir Romanovsky of the UAF Geophysical Institute and the co-author of the study stated that with the further thawing of sub-lake permafrost there is a good chance that the ground will descend. This increases the lake depth and quickening further permafrost thawing. He further said that the warming on the land may augment the protective vegetation layer and defer thawing of permafrost outside of lakes.

Arp also said that with increasingly warmer and snowier winters producing thinner lake ice, the shallow lakes will likely continue to warm.