Indications that methane levels might be rising after almost a decade of stability came last month, when the US National Oceanic and Atmospheric Administration (Noaa) released a preliminary analysis of readings taken at monitoring stations worldwide.
Noaa suggested that 2007 had seen a global rise of about 0.5%.
Some stations around the Arctic showed rises of more than double that amount.
Ed Dlugokencky, the scientist at Noaa's Earth System Research Laboratory (ESRL) who collates and analyses data from atmospheric monitoring stations, agrees that the 2007 rise has a biological cause.
"We're pretty sure it's not biomass burning; and I think 2007 is probably down to wetland emissions," he said.
"In boreal regions it was warmer and wetter than usual, and microbes there produce methane faster at higher temperatures."
Dr Dlugokencky also suggested that the drastic reduction in summer sea ice around the Arctic between 2006 and 2007 could have increased release of methane from seawater into the atmosphere.
A further possibility is that the gas is being released in increasing amounts from permafrost as temperatures rise.
Researchers will be keeping a close eye on this year's data which will indicate whether 2007 was just a blip or the beginning of a sustained rise.
Methane concentrations had been more or less stable since about 1999 following years of rapid increases, with industrial reform in the former Soviet bloc, changes to rice farming methods and the capture of methane from landfill sites all contributing to the levelling off.
In the recent past, concentrations have risen during El Nino events, whereas the world is currently amid the opposite climatic pattern, La Nina.
An upturn in methane concentrations emissions could have significant implications for the Earth's climatic future.
A sustained release from Arctic regions or tropical wetlands could drive a feedback mechanism, whereby higher temperatures liberate more of the greenhouse gas which in turn forces temperatures still higher.
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Methane levels might be rising after almost a decade of stability (3 posts)
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Posted 16 years ago #
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Exclusive: The methane time bomb
Arctic scientists discover new global warming threat as melting permafrost releases millions of tons of a gas 20 times more damaging than carbon dioxide
Preliminary findings suggest that massive deposits of subsea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats
The first evidence that millions of tons of a greenhouse gas 20 times more potent than carbon dioxide is being released into the atmosphere from beneath the Arctic seabed has been discovered by scientists.
The Independent has been passed details of preliminary findings suggesting that massive deposits of sub-sea methane are bubbling to the surface as the Arctic region becomes warmer and its ice retreats.
Posted 16 years ago # -
Maybe this is what we need to wake people up.
U.S. National Labs Probe Abrupt Climate Change
http://www.ens-newswire.com/ens/sep2008/2008-09-22...
For 40 years earth scientists have worried about what would happen if global warming eventually caused the West Antarctic ice sheet, some 3.8 million cubic kilometers of ice, to break up and slide into the ocean. Global climate stability depends on the integrity of the West Antarctic ice sheet. (Photo courtesy NASA) In January 2006, in a report commissioned by the UK government, the head of the British Antarctic Survey, Chris Rapley, warned that this huge west Antarctic ice sheet may be starting to disintegrate.
James Hansen, a senior NASA scientist, said the results of Rapley's study were deeply worrying. "Once a sheet starts to disintegrate, it can reach a tipping point beyond which break-up is explosively rapid," he said.
Sea level would rise four to six meters - 13 to 20 feet. Port facilities worldwide would be submerged; atolls and island chains would vanish; parts of Bangladesh, Brazil, Burma, America's Gulf States, and other low-lying areas would flood; Venice, New Orleans, and many other cities would sink.
It is now apparent that these events may not be "eventual." Abrupt climate change could cause rapid melting and the subsequent rise of sea level not by centimeters but by meters per century.
Posted 16 years ago #
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