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Environment

UAF Study Shows Permafrost in Alaska Cools the Climate When Melted

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Katey Walter Anthony
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A new study released by the University of Alaska Fairbanks shows arctic thermokarst lakes maintain climate change by storing greenhouse gases. 

The study published in the scientific journal Nature suggests arctic thermokarst lakes are “net climate coolers.” Thermokarst lakes are thawing bodies of water with ice-rich permafrost.  These bodies of water are formed when permafrost is melted and creates dips in the surface that then are filled with melted water. 

Associate research professor at the University of Alaska Fairbanks Institute of Northern Engineering Katey Walter Anthony is the lead researcher on the study.  She says the thermokarst lakes create short term warming because of the methane they release but ultimately cause cooling because of the carbon they soak up.

“These lakes tend to be deep and that means that they gratify and they have anaerobic bottoms. So when the plants around the lake fall into the lake or the plants in the lake die, their remains go into the bottom of this lake that is without oxygen and that really slows down the decomposition. So you can end up storing relatively undecomposed plant matter both aquatic origin and terrestrial origin in these lakes.”

The study said researchers found that these lakes warmed the planet over 5,000 years ago.  However, around that time, something switched and the thermokarst lakes began to cool earth.  Because of that, Anthony says, the lands that are now frozen have an incredibly high level of carbon.

Anthony says eventually these thermokarst lakes drain and the carbon that was absorbed is now stuck in ice. 

“What’s not good is that permafrost is projected to thaw in the future which widespread permafrost thaw will subject all of that carbon that’s frozen in the ground, it will thaw it out and it will be subject to microbial decomposition which will produce more CO2 and more methane.”

The study looked at the permafrost lakes in Siberia using radiocarbon dating, atmospheric modeling and spatial analysis.  30 percent of the world’s permafrost carbon is in seven percent of the permafrost in Alaska, Canada and Siberia. 

Although these lakes produce methane naturally, the worry is the compacted levels of methane when manmade sources are taken into consideration. Natural methane sources, including thermokarst lakes, accounts for 250 million tonnes of methane, whereas manmade sources produce 320 million.