Methane gas is an
extremely potent greenhouse gas, ten to twenty times more efficient at retaining atmospheric heat than CO2. The good news is that it "only" lasts about 10 years or so in the atmosphere before it breaks down into CO2 (!) and water. By comparison, it will take centuries to get CO2 back to pre-industrial revolution levels, even if we stopped producing any of it today.
As global temperatures rise, it's effects have been felt most in the arctic and Antarctic regions. The permafrost is thawing and is believed to have the potential of releasing billions of tons of methane into the atmosphere in a short span of years, very quickly exacerbating global warming by 10-25%. There is some question about whether the methane will be released directly into the atmosphere or will oxidize in the peat and be released merely as CO2, but the potential for a huge catastrophe is in the making.
As if this weren't bad enough, I'll reveal a new arctic methane threat below the fold.
Apparently, the methane isn't just stored in the permafrost. It's
stored in sea ice as methane hydrate.
NEW YORK (Reuters) - If the world continues to get warmer, vast amounts of methane gas trapped in ice under the sea could belch up and worsen climate change, according to a study.
"We may have less time than we think to do something (about the prospect of global warming)," Dr. Ira Leifer, a marine scientist at University of California Santa Barbara, said in an interview.
Leifer is the main author of a study that looks at how "peak blowouts" of melting undersea formations called methane hydrates could release the potent greenhouse gas into the atmosphere.
How does it happen? Volcanically created methane slowly seeps from cracks in the ocean floor. As it rises up through the water, it gets caught in crystal "cages" of water ice. Since the ice in the arctic hasn't melted in thousands of years, methane has had a long time to accumulate.
As this initial methane enters the atmosphere, it causes more ice to melt which causes ocean temps to rise (frozen oceans reflect 80% of the sun's radiation, while liquid oceans absorb 80% of it). As the ocean temps rise, deeper methane hydrates stored in sediment in the ocean floor destabilizes, releases, and enters the atmosphere creating a positive feedback loop of ocean warming that could release vast amounts of methane. The amount of methane stored in hydrates world wide is estimated at 200,000 trillion cubic feet (dwarfing the amount of methane in the permafrost), or about 4.26 trillion tons (calculated at methane gas is 19 grams per cubic foot), although it's not clear that all of this would be released.
The accumulation of methane hydrate in the ocean is hypothesized to be a part of the natural cycle of ice ages and warmer periods that our planet has experienced over the past several million years. During each of these periods, the methane was released quickly (50-100 years), global warming occurred, and all the ice melted. However, shortly thereafter the methane would have dissipated, and the global temperature would have been able to return to normal, allowing a slow but steady environmental recovery.
Today's situation is unique. Not since the age of the dinosaurs have the CO2 levels been so high, currently approaching 400ppm. Nor since that time has methane been mixed with such high concentrations of CO2 in our atmosphere. Currently we're creating our current global warming woes by "only" putting about 27 billion tons of CO2 into the air each year. Given the incredible amount of methane stored in hydrates and it's exponentially greater effect on global warming in the short term, this gas and its effects must be given the credence it deserves.