Permafrost thawing much faster under Interior Alaska lakes than first thought

Abrupt Thawing of Permafrost Beneath Arctic Lakes could Fuel Climate Change

Credit Clayton Elder

These pools significantly speed up the thawing of the permafrost, which leads to food being available to microbes that consequently produce carbon dioxide and methane.

Also germane to the discussion is the fact that this region under the Arctic landscape contains a huge reserve of organic carbon that has, until recently, been safely contained by the frozen soil of the permafrost.

Researchers studied methane released by thawing permafrost under thermokarst lakes in the Arctic.

So, we measured the carbon emissions in 72 different locations in 11 thermokarst lakes in areas of Siberia and Alaska, and in five places without lakes, to understand, how much is a greenhouse gas, and also with the goal of measuring the age of contained carbon. By combining field work results with remote-sensing data of lake changes during the past two years, they determined the "abrupt thaw" beneath such lakes is likely to release large amounts of permafrost carbon into the atmosphere this century.

Jasmine holds a Master's in Journalism from Ryerson University in Toronto and writes professionally in a broad variety of genres. With thermokarst lakes, methane becomes the dominant driver responsible for 70 to 80 percent of warming-driven directly by permafrost thawing this century.

When this happens under thermokarst lakes, formed an even more grim picture, as the water on the surface accelerates melting on the bottom.

A new NASA-funded study focuses on a mechanism that could accelerate the release of this atmospheric carbon, the result of thermokarst lakes.

Because the same amount of ice takes up more volume than water, the land surface slumps and subsides, creating a small depression that then fills with water from rain, snow melt and ground ice melt.

"Within decades you can get very deep thaw-holes, meters to tens of meters of vertical thaw", Walter Anthony said. Permafrost in terrestrial environments generally experiences shallow seasonal thawing over longer time spans.

They compared the emissions from lakes to five locations where gradual thawing occurs. "Ancient greenhouse gases go out".

These ancient greenhouse gases, produced from microbes chewing through ancient carbon stored in the soil, range from 2,000 to 43,000 years old.

Team members with the Alfred Wegener Institute (AWI) for Polar and Marine Research in Germany then used U.S. Geological Survey-NASA Landsat satellite imagery from 1999 to 2014 to determine the speed of lake expansion across a large region of Alaska.

This type of lake-related thawing has not been incorporated into previous climate change models, Walter Anthony noted.

Human fossil fuel emissions are the number one source of greenhouse gases to the atmosphere, and in comparison, methane emissions from thawing permafrost make up only one percent of the global methane budget, Walter Anthony said.

Altre Notizie