永久冻土消融会加速全球变暖

A team of researchers lead by Florida State University have found new evidence that permafrost（永久冻土） thawing² is releasing large quantities of greenhouse gases into the atmosphere via plants, which could accelerate warming trends. The research is featured in the newest edition of the Proceedings³ of the National Academy of Sciences.   "We've known for a while now that permafrost is thawing," said Suzanne Hodgkins, the lead author on the paper and a doctoral student in chemical oceanography at Florida State. "But what we've found is that the associated changes in plant community composition in the polar regions could lead to way more carbon being released into the atmosphere as methane⁴（甲烷）."   Permafrost is soil that is frozen year round and is typically located in polar regions. As the world has gotten slightly warmer, that permafrost is thawing and decomposing⁵, which is producing increased amounts of methane.   Relative to carbon dioxide, methane has a disproportionately large global warming potential. Methane is 33 times more effective at warming Earth on a mass basis and a century time scale relative to carbon dioxide.   As the plants break down, they are releasing carbon into the atmosphere. And if the permafrost melts entirely⁶, there would be five times the amount of carbon in the atmosphere than there is now, said Jeff Chanton, the John Widmer Winchester Professor of Oceanography at Florida State.   "The world is getting warmer, and the additional release of gas would only add to our problems," he said.   Chanton and Hodgkins' work, "Changes in peat chemistry associated with permafrost thaw¹ increase greenhouse gas production," was funded by a three-year, $400,000 Department of Energy grant. They traveled to Sweden multiple times to collect soil samples for the study.   The research is a multicontinent effort with researchers from North America, Europe and Australia all contributing to the work.