Feb 112010
 
English: AIRS 2006-2009 annual mean upper trop...

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Could methane-digesting bacteria and an Arctic cap of fresh water prevent a climate catastrophe?

Methane trapped in Arctic ice (and elsewhere) could be rapidly released into the atmosphere as a result of global warming in a possible doomsday scenario for climate change, some scientists worry. After all, methane is 72 times more powerful as a greenhouse gas than carbon dioxide over a 20-year timescale. But research announced at the annual meeting of the American Geophysical Union this December suggests that marine microbes could at least partially defeat the methane “time bomb” sitting at the bottom of the world’s oceans.

The conventional wisdom for decades has been that methane emanating from the seafloor could be consumed by a special class of bacteria called methanotrophs. It has long been known, for instance, that these organisms at the bottom of the Black Sea consume methane produced in its deep oxygen-free waters.

What has not been clear is whether these bacteria would be of any use in the event that a special class of ice at the bottom of the ocean is destabilized by a warmer climate. This ice, known as clathrates, or methane hydrates, consists of a cage of water molecules surrounding individual molecules of methane, and it exists under conditions of low temperature and high pressure. These conditions can be found on the continental shelf the world over, but there is an extra large quantity of seafloor suitable for methane hydrates in the Arctic because of its low temperatures and a seafloor plateau that happens to be at the optimum depth for clathrate formation. The Arctic also happens to be more vulnerable to climate change because parts of the poles are warming at least twice as fast as the rest of the world.

To investigate this Arctic ice more carefully, Scott Elliott, a biogeochemist at Los Alamos National Laboratory, used the Coyote supercomputer to model the complex interplay of physical and biological systems that govern the fate of methane released from Arctic clathrates during the first few decades of projected future global warming.

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