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Methane a major worry in climate change

Bearing in mind that many scientists are wary about making long term predictions about climate change, and with a spate of exaggerated headlines trumpeting dangerous climate change science, the need to for accurate scientific evidence into climate change has never been more important. But it now seems that the effect of methane on climate change has been seriously underestimated as scientists have failed to take into account the gas’s reaction with airborne particles called aerosols according to new research from NASA. The ever nearing Copenhagen 15 conference on climate change conference will be looking primarily at carbon dioxide emissions but other greenhouse gases which include methane, nitrous oxide and halocarbons are also important in climate change –  and some are far more dangerous than CO2 and even more worrying is the fact that they may have more negative impacts than had been previously thought.  Drew Shindell, a climatologist at NASA’s Goddard Institute for Space Studies in New York explained that molecules of methane gas, the second most important greenhouse gas “undergo chemical changes and once they do, looking at them after they’ve mixed and changed in the atmosphere doesn’t give an accurate picture of their effect”. Dr Shindell said “For example, the amount of methane in the atmosphere is affected by pollutants that change methane’s chemistry, and it doesn’t reflect the effects of methane on other greenhouse gases,” said Shindell, “so it’s not directly related to emissions, which are what we set policies for.”  Molecule for molecule, methane was thought to be 20 times more potent than carbon dioxide as a greenhouse gas, but focus has remained on CO2 as it is s much more abundant than methane and the predicted growth rate is far greater. However the research shows that Methane has 33 times as much effect on climate change compared to CO2, up from 25 times used in standard estimates, although methane breaks down much more quickly than CO2 (which is also largely unreactive). Dr Shindell told the Times newspaper (October 30th 2009) “for long term climate change there is no way round dealing with CO2 – it’s the biggest thing and lasts hundreds of years – but if we were to have a concerted effort to deal with non CO2 we would have a very large impact on the near term”.  And whilst Dr Shindell agreed that current efforts should focus on CO2, the new research also casts doubt on current predictions on rises in global temperature. Current IPCC predictions are that the world will warm between 1.1C and 6C by 2100.  2C is seen as the global tipping point after which irreversible damage will be done to the planet. The research also casts doubts on whether carbon trading schemes will be effective if they focus only on CO2.  Sources of methane include agriculture, gases escaping from landfill and fossil fuels. According to Professor Mark Maslin of UCL, one source is likely to be the release of the planet’s methane hydrate deposits. These ice-like deposits are found on the seabed and in the permafrost regions of Siberia and the far north. “These permafrost deposits are now melting and releasing their methane,” said Maslin. “You can see the methane bubbling out of lakes in Siberia. And that is a concern, for the impact of methane in the atmosphere is considerable. It is 25 times more powerful than carbon dioxide as a greenhouse gas.” A build-up of permafrost methane in the atmosphere would produce a further jump in global warming and accelerate the process of climate change. Even more worrying, however, is the impact of rising sea temperatures on the far greater reserves of methane hydrates that are found on the sea floor. It was not just the warming of the sea that was the problem, added Maslin. As the ice around Greenland and Antarctica melted, sediments would pour off land masses and cliffs would crumble, triggering underwater landslides that would break open more hydrate reserves on the sea-bed. Again there would be a jump in global warming. “These are key issues that we will have to investigate over the next few years,” he said.  “If we control methane, which the U.S. is already starting to do, then we are likely to mitigate global warming more than one would have thought, so that’s a very positive outcome,” Dr Shindell said. “Control of methane emissions turns out to be a more powerful lever to control global warming than would be anticipated.”

http://earthobservatory.nasa.gov/Newsroom/view.php?id=27355

http://www.guardian.co.uk/environment/2009/sep/06/global-warming-natural-disasters-conference