For millennia, layers of animal waste and other organic matter left behind by the creatures that used to roam the Arctic tundra have been sealed inside the frozen permafrost. Now climate change is thawing the permafrost and lifting this prehistoric ooze from suspended animation.

But Sergei Zimov, a scientist who for almost 30 years has studied climate change in Russia’s Arctic, believes that as this organic matter becomes exposed to the air it will accelerate global warming faster than even some of the most pessimistic forecasts.

When the organic matter left behind by mammoths and other wildlife is exposed to the air by the thawing permafrost, his theory runs, microbes that have been dormant for thousands of years spring back into action. As a by-product they emit carbon dioxide and — even more damaging in terms of its impact on the climate — methane gas.

[Read](http://www.msnbc.msn.com/id/20819312/ “Read the Story”) (Reuters via MSNBC)