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Wednesday, January 21, 2009

The hydrate hazard (methane)

Research Highlights

Nature Reports Climate Change, published online: 15 January 2009 | doi:10.1038/climate.2009.2

The hydrate hazard

by Anna Armstrong

J. Geophys. Res. doi:10.1029/2008JC004938 (2008)

The hydrate hazard


A moderate increase in sea-floor temperature could trigger the widespread release of methane from ocean hydrates, finds new research. Large quantities of the potent greenhouse gas are stored beneath the sea in solid crystalline structures, known as hydrates, that could potentially be destabilized by ocean warming.

Matthew Reagan and George Moridis of the Lawrence Berkeley National Laboratory in Berkeley, California, used computer simulations to examine the effect of 100 years of moderate ocean warming on the stability of deep and shallow ocean hydrates. They found that deep ocean deposits remained stable over the 100-year period, but that shallow ocean deposits were highly unstable, releasing significant quantities of dissolved and gaseous methane in response to just 1 °C of warming at the sea floor. Of the shallow deposits examined, cold hydrates, representative of the Arctic continental shelf, released nearly three times more methane than those representative of warm regions such as the Gulf of Mexico.

An increase in deep-sea pressure resulting from sea level rise would delay methane release but would not prevent its inevitable escape into the sea, say the researchers. Given that the release of methane could amplify climate change, the authors call for a detailed assessment of the hydrate hazard.

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