New Zealand's methane effect worse than thought

New Zealand Herald: New Zealand may be making a bigger contribution to global warming than scientists thought. A Nasa study says climate scientists have underestimated by 20 to 40 per cent how much methane warms the planet - even though it is already believed to be 25 times more potent than carbon dioxide.

The study, led by Nasa's Goddard Institute for Space Studies in New York, said methane blocked the creation of aerosols that would otherwise cool the planet - a new finding not counted in current estimates of global warming. New Zealand is almost unique in the developed world because of its large proportion of methane emissions. The gas is released by farm animals, as well as landfills, crops and coal mines.

New Zealand scientists reacted cautiously to the new study, saying more work was needed to back it up. A New Zealand author of the latest report of the Intergovernmental Panel on Climate Change, Martin Manning, said at least one more study showing the same thing would be needed before the panel would change its stance. It was a "very short paper on a very complex topic" but it would open up debate, he said.

Pastoral Greenhouse Gas Research Consortium manager Mark Aspin said New Zealand would be looking to the IPCC for guidance, "given our [emissions] profile it is something we want to keep an eye on". The study found methane and another pollutant, carbon monoxide, soaked up an atmospheric "scrubber" called hydroxyl that would otherwise join other substances to make cooling aerosols. The sulphate aerosols elbowed aside by methane cooled the earth by scattering light and affecting the clouds….

Lake Marian in Fiordland National Park near the Homer Tunnel on the road to Milford Sound, New Zealand, shot by Thorney¿?, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License