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Most of this yedoma is in north and eastern Siberia, areas that until recently had not been studied at length by scientists. What makes this permafrost special is that during a rapid onset ice age, carbon-rich plants were trapped in the permafrost. As the permafrost thaws, the carbon is released as methane if it's underwater in lakes, like much of the parts of Siberia that Walter studied. If it's dry, it's released into the air as carbon dioxide. Scientists aren't quite sure which is worse. Methane is far more powerful in trapping heat, but only lasts about a decade before it dissipates into carbon dioxide and other chemicals. Carbon dioxide traps heat for about a century. "The bottom line is it's better if it stays frozen in the ground," Schuur said. "But we're getting to the point where it's going more and more into the atmosphere." Vladimir Romanovsky, geophysics professor at the University of Alaska at Fairbanks, said he thinks the big methane or carbon dioxide release hasn't started yet, but it's coming. It's closer in Alaska and Canada, which only has a few hundred square miles of yedoma, he said. In Siberia, the many lakes of melted water make matters worse because the water, although cold, helps warm and thaw the permafrost, Walter said.
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