Climate-cooling arctic lakes soak up greenhouse gases, study finds

Jul 16, 2014
Found in the Arctic and cold mountain regions, thermokarst lakes occur as permafrost thaws and creates surface depressions that fill with melted freshwater, converting what was previously frozen land into lakes. Pictured: A close-up look at a small arctic thermokarst lake. Credit: UAF / Katey Walter Anthony

New University of Alaska Fairbanks research indicates that arctic thermokarst lakes stabilize climate change by storing more greenhouse gases than they emit into the atmosphere.

Countering a widely-held view that thawing permafrost accelerates atmospheric warming, a study published this week in the scientific journal Nature suggests 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," says lead researcher Katey Walter Anthony, associate research professor at the UAF 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."

Found in the Arctic and cold mountain regions, thermokarst lakes occur as permafrost thaws and creates surface depressions that fill with melted fresh water, converting what was previously frozen land into lakes. 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, " in peat-rich sediments occurs over millennial time scales."

Researchers observe that roughly 5,000 years ago, thermokarst lakes in ice-rich regions of North Siberia and Alaska began cooling, instead of warming the atmosphere. Pictured: An overhead view of arctic thermokarst lakes. Credit: UAF photo courtesy of Katey Walter Anthony

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 and greenhouse gas emissions.

Researchers found that "thermokarst basins switched from a net radiative warming to a net cooling climate effect about 5000 years ago," according to their article, published online today. They found that high rates of carbon accumulation in lake sediments were stimulated by several factors, including "thermokarst erosion and deposition of terrestrial organic matter, […] nutrient release from thawing permafrost that stimulated lake productivity, and by slow decomposition in cold, anoxic lake bottoms."

In this image, Katey Walter Anthony, associate research professor at UAF, collects data samples from an arctic thermokarst lake. Credit: UAF photo courtesy of Katey Walter Anthony

"These lakes are being fertilized by thawing yedoma permafrost," explained co-author Miriam Jones, research geologist for the U.S. Geological Survey. Yedoma is a type of permafrost that is rich in organic material. "So mosses and other plants flourish in these lakes, leading to carbon uptake rates that are among the highest in the world, even compared to carbon-rich peatlands."

The study also revealed another major factor of this process: Researchers found that when the lakes drain, previously thawed organic-rich lake sediments refreeze. The new permafrost formation then stores a large amount of carbon processed in and under thermokarst lakes, as well as the peat that formed after drainage. Researchers note that the new carbon storage is not forever, since future warming will likely start rethawing some of the permafrost and release some of the carbon in it via microbial decomposition.

As roughly 30 percent of global permafrost carbon is concentrated within 7 percent of the permafrost region in Alaska, Canada, and Siberia, this study's findings also renew scientific interest in how carbon uptake by thermokarst lakes offsets . Through its data collection, the study expanded the circumpolar peat pool estimate for regions by more than 50 percent.

Explore further: New permafrost is forming around shrinking Arctic lakes, but will it last?

More information: A shift of thermokarst lakes from carbon sources to sinks during the Holocene epoch, Nature, dx.doi.org/10.1038/nature13560

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User comments : 10

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kelman66
4.5 / 5 (8) Jul 16, 2014
Interesting.
Nevertheless, the last thing we need in the short term is more emissions.
antigoracle
2.1 / 5 (14) Jul 16, 2014
Another nail in the coffin of AGW ignorance.
runrig
4 / 5 (13) Jul 17, 2014
Another nail in the coffin of AGW ignorance.


Unfortunately not yours and - no - did you not comprehend this? ....

"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."

Mankind, now present as not before during this process - will have to wait a "tad" before the benefit kicks in eh?
FFS
thermodynamics
3.8 / 5 (10) Jul 17, 2014
Another nail in the coffin of AGW ignorance.


AntiEm: Please explain why you think this is a nail in the coffin of AGW?

First, it was my impression that you though AGGs did not have an affect on the climate. So, if that was true, why would any change to the fundamental of CO2 affecting climate?

Are you admitting you understand that CO2 does cause warming and we are affecting the CO2 levels in the atmosphere?

Have you shown the folks at the contest web site how you can falsify AGW yet? I want you to win so I get my cut.
antigoracle
1.7 / 5 (11) Jul 17, 2014
So runrig, all this methane and CO2 is being released in the tundra and yet the planet and northern oceans are cooling. As I said, another nail in the coffin of AGW lies and ignorance.
http://wattsupwit...fiction/
runrig
4.3 / 5 (6) Jul 17, 2014
So runrig, all this methane and CO2 is being released in the tundra and yet the planet and northern oceans are cooling. As I said, another nail in the coffin of AGW lies and ignorance.
http://wattsupwit...fiction/


http://blog.hotwh...rry.html

thermodynamics
3.7 / 5 (6) Jul 17, 2014
So runrig, all this methane and CO2 is being released in the tundra and yet the planet and northern oceans are cooling. As I said, another nail in the coffin of AGW lies and ignorance.
http://wattsupwit...fiction/


http://blog.hotwh...rry.html

Run: Great post. The issue we constantly run into is that those who need to understand this can't read or understand. It should come as no surprise that the disingenuous use of plotting to obfuscate the information is successful on Watts blog. We run into it all the time here when the deniers just read what they want from articles.
antigoracle
1.7 / 5 (6) Jul 18, 2014
runrig
4 / 5 (4) Jul 18, 2014
http://www.telegraph.co.uk/earth/environment/10916086/The-scandal-of-fiddled-global-warming-data.html


http://www.thegua...sleading
http://www.thegua...r-booker

http://skepticals...ted.html
Eddy Courant
1 / 5 (4) Jul 20, 2014
Katey diddit now. She's going to lose her research grants coming up with the wrong answers.