UNDERSTANDING THE contribution of North Siberia thaw lakes to global atmospheric methane is critical, because the concentration of that potent greenhouse is highest at that latitude, has risen sharply in recent decades and exhibits a significant seasonal jump at those high northern latitudes.

Exacerbating the cycle

As the permafrost melts in North Siberia due to climate change, carbon sequestered and buried there since the Pleistocene era is bubbling up to the surface of Siberian thaw lakes and into the atmosphere as methane, a greenhouse gas 20 times more potent than carbon dioxide.

In turn, that bubbling methane held captive as carbon under the permafrost for more than 40,000 years is accelerating global warming by heating the Earth even more — exacerbating the entire cycle. These were the findings of a study co-authored by a Florida State University scientist and published in the Sept. 7 issue of the journal Nature.

According to FSU oceanography Professor Jeff Chanton and study co-authors at the University of Alaska-Fairbanks, this is not good for the quality of human life on Earth. Chanton points to the thawing permafrost along the margins of the thaw lakes — which comprise 90 per cent of the lakes in the Russian permafrost zone — as the primary source of methane released in the region.

During the yearlong study, he performed the isotopic analysis and interpretation to determine the methane's age and origin and assisted with measurements of the methane bubbles' composition to shed light on the mode of gas transport, according to a FSU press release.

Positive feedback

"My fellow researchers and I estimate that an expansion of these thaw lakes between 1974 and 2000, a period of regional warming, increased methane emissions by 58 per cent there," said Chanton. — Our Bureau

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