As climate change warms the Arctic, permafrost is thawing, and carbon trapped within the soil is moving into the atmosphere. Permafrost stores twice as much carbon as the atmosphere, but the degree to which this frozen carbon will thaw and accelerate climate change has remained a point of scientific inquiry. Taking widespread on-the-ground permafrost measurements is not logistically feasible in the remote Far North.

By documenting Alaska’s lakes and ponds in unprecedented detail, Levenson and colleagues show where and how water bodies can signal underlying permafrost thaw, providing a step toward a straightforward, easily applicable method for keeping tabs on how the Arctic is changing. The research is published in the journal Geophysical Research Letters.

Thawing permafrost can shift erosion rates, vegetation growth, and soil permeability, which can cause lakes to form, grow, and drain. To examine how the relationship between lake area and the extent of intact permafrost varies across Alaska, the researchers used images taken nearly daily at 10-meter resolution by the Sentinel-2 satellite to identify and track changes in more than 800,000 bodies of water across the state.

They report that thawing permafrost appears to reduce the size of lakes in landscapes untouched by glaciers where bedrock is not exposed at the surface. Conversely, in areas that were recently carved by moving glaciers, lake area sometimes increases as permafrost thaws. In some cases, no clear relationship between the two exists.

Receding glaciers usually leave behind new lakes; however, the formation of these lakes may be delayed until permafrost thaws and new depressions can form. The rugged topography and less permeable sediment in glacial landscapes could also explain why lakes in glaciated and unglaciated regions react to permafrost thaw differently, the researchers say.

The authors are not the first to consider the relationship between lake area and permafrost thaw, but they are among the first to describe how a lake‘s response to ongoing thaw depends on its geologic history. The researchers say the dataset they produced, which they call the Alaska Lake and Pond Occurrence Dataset, could greatly simplify research aimed at investigating how permafrost is changing as the Arctic warms.

This story is republished courtesy of Eos, hosted by the American Geophysical Union. Read the original story here.