Analysis of 27 undisturbed tundra sites and additional landslide zones in northern Alaska shows that newly thawed permafrost is releasing carbon dioxide into the atmosphere at a rate much higher than thought, according to a new report from the National Academy of Sciences. From the Climate News Network :
Once the ice melts, microbes get to work releasing carbon dioxide into the air. The soil thaws, the surface collapses, lakes form, water flows, land surfaces erode which in turn releases more carbon dioxide to create more warming, to make the tundra even more vulnerable to spring thaw, and of course to accelerated warming. ... The places they examined had been frozen for at least 10,000 years, and in some places two million years.
The team found dissolved organic carbon in all of them, and they found that newly-exposed muddy water was liable to surrender 40% more CO2 to the atmosphere. This has of course been going on at the fringe of the Arctic permafrost for at least 10,000 years. The hazard is not in the process itself, but in its potential acceleration.
Previous research has focused  on the release of methane, another greenhouse gas, into the atmosphere from thawing tundra.
Read more: Thawing tundra a threat to frozen carbon