Apr 4, 2012
Insight: climate change could boost greenhouse-gas emissions from thawing permafrost
The highest concentrations of atmospheric methane and carbon dioxide are found in the Arctic, north of the areas where the most man-made methane and carbon dioxide are created. Our recent analyses suggest that during the Holocene and previous "warm stages", thawing of subsea permafrost (including disturbance of gas hydrates and bottom erosion), degradation of onshore permafrost (caused by coastal erosion, for example), and the formation and evolution of thawing lakes are also responsible for the Arctic increase in these gases.
This hypothesis is backed up by the close connection between the distribution and dynamics of methane and carbon dioxide (between 1992 and 2011) and their water-to-air fluxes, and degradation of permafrost (Environmental Research Letters (ERL)).
The release of large stores of carbon from the surrounding Arctic landmasses through coastal and bottom erosion, and from rivers into the Arctic Ocean, is leading to a net increase of carbon dioxide into the atmosphere over the vast East Siberian Arctic Shelf (ESAS).
The ESAS, which is the broadest and shallowest ocean shelf worldwide, exhibits the lowest values of calcium carbonate saturation ever reported for the open marine environment.
Before this work, no real observations had been performed on carbonate systems and dissolved methane distribution – and their dynamics – in the ESAS, along the entire Northern Sea Route and Lena River. What is more, the researchers found that fluxes of carbon dioxide and methane are important for the marine carbon cycle in the Arctic seas – something that has never been included in the regional and global carbon balance.
Methane release from the ESAS is determined by the current state of sub-sea permafrost, which has failed to seal ancient carbon pools, including hydrates sequestered in seabed deposits within and beneath permafrost.
About the author
Research associate Prof. Igor Semiletov leads the International Siberian Shelf Study Group at the International Arctic Research Center (IARC)/University Alaska Fairbanks (UAF) and the Pacific Oceanological Institute (POI)/Far Eastern Branch of the Russian Academy of Sciences (FEBRAS).