As temperatures rise, some of the organic carbon stored in Arctic permafrost meets an unexpected fate--burial at sea. As many as 2.2 million metric tons of organic carbon per year are swept along by a single river system into Arctic Ocean sediment, according to a new study an international team of researchers published today in Nature. This process locks away carbon dioxide (CO2) -- a greenhouse gas -- and helps stabilize the earth's CO2 levels over time, and it may help scientists better predict how the natural carbon cycle will interplay with the surge of CO2 emissions due to human activities."The erosion of permafrost carbon is very significant," says Woods Hole Oceanographic Institution (WHOI) Associate Scientist Valier Galy, a co-author of the study. "Over thousands of years, this process is locking CO2 away from the atmosphere in a way that amounts to fairly large carbon stocks. If we can understand how this process works, we can predict how it will respond as the climate changes."