Extinction .in

Antarctic may host methane stores

[[{"type":"media","view_mode":"media_crop","fid":"127","attributes":{"alt":"","class":"media-image","id":"media_crop_6810678576135","media_crop_h":"0","media_crop_image_style":"-1","media_crop_instance":"17","media_crop_rotate":"0","media_crop_scale_h":"0","media_crop_scale_w":"0","media_crop_w":"0","media_crop_x":"0","media_crop_y":"0","typeof":"foaf:Image"}}]]

 
Ancient organic matter could be converted to methane by microbes.
 

Large volumes of methane - a potent

greenhouse gas - could be locked beneath the ice-covered regions of Antarctica,

according to a new study.

It says this methane could be released into the atmosphere as ice retreats,

contributing to climate warming.

The findings indicate that ancient deposits of organic matter may have been

converted to methane by microbes under the ice.

An international team reported the results in Nature journal.

Study leader Jemima Wadham, from Bristol University, said: "This is an

immense amount of organic carbon, more than ten times the size of carbon stocks

in northern permafrost regions.

"Our laboratory experiments tell us that these sub-ice environments are also

biologically active, meaning that this organic carbon is probably being

metabolised to carbon dioxide and methane gas by microbes."

They estimate that there could be hundreds of billions of tonnes of carbon

stored in methane reservoirs under the ice sheet.

The authors say that the predicted shallow depth of these methane reserves

means that they could be destabilised by climate change, and might act as a

positive feedback on global warming.

Co-author Dr Sandra Arndt, also from the University of Bristol, said: "It's

not surprising that you might expect to find significant amounts of methane

hydrate trapped beneath the ice sheet.

"Just like in sub-seafloor sediments, it is cold and pressures are high which

are important conditions for methane hydrate formation."

In their Nature paper, the authors comment that their "findings suggest that

the Antarctic Ice Sheet may be a neglected but important component of the global

methane budget".