New research, supported by the National Science Foundation (NSF), counters a widely-held scientific view that thawing permafrost uniformly accelerates atmospheric warming, indicating instead that certain Arctic lakes store more greenhouse gases than they emit into the atmosphere.
The study, published this week in the journal Nature, focuses on thermokarst lakes, which occur as permafrost thaws and creates surface depressions that fill with melted fresh water, converting what was previously frozen land into lakes.
The research suggests that Arctic thermokarst lakes are "net climate coolers" when observed over longer, millennial, time scales.
"Until now, we've only thought of thermokarst lakes as positive contributors to climate warming," said lead researcher Katey Walter Anthony, associate research professor at the University of Alaska Fairbanks Institute of Northern Engineering. "It is true that they do warm climate by strong methane emissions when they first form, but on a longer-term scale, they switch to become climate coolers because they ultimately soak up more carbon from the atmosphere than they ever release."
The researchers observed that roughly 5,000 years ago, thermokarst lakes in ice-rich regions of North Siberia and Alaska began cooling, instead of warming the atmosphere.
"While methane and carbon dioxide emissions following thaw lead to immediate radiative warming," the authors write, "carbon uptake in peat-rich sediments occurs over millennial time scales."
Using published data from the circumpolar Arctic, their own new field observations of Siberian permafrost and thermokarsts, radiocarbon dating, atmospheric modeling and spatial analyses, the research team studied how thawing permafrost is affecting climate change and greenhouse gas emissions.
Researchers found that "thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5,000
|Contact: Peter West|
National Science Foundation