In a nutshell: Widespread Melting in the arctic = widespread melting of permafrost = decomposition of organic matter that has been in deep freeze for centuries = massive release of CO2 and methane in the process = doom and …uh… gloom.
From the Daily Galaxy:
For thousands of years animal waste, and other organic matter left behind on the Arctic tundra, have been sealed off from the environment by permafrost. Now climate change is melting the permafrost and freeing mass quantities of prehistoric â€œoozeâ€ from its state of suspended animation.
Russian scientist, Sergei Zimov, has been studying climate change in Russia’s Arctic for 30 years now. He is worried that as this organic matter becomes exposed to the air it will drastically accelerate global warming predictions even beyond some of the most pessimistic forecasts.
Hmm, I had always thought that current climate models took the permafrost melting into account. Perhaps not. Must do more sleuthing to see.