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Monday, December 12, 2016

Methane surge needs urgent attention.

Methane surge needs urgent attention. Scientists say they are concerned at the rate at which methane in the atmosphere is now rising. After a period of relative stagnation in the 2000s, the concentration of the gas has surged. Methane (CH4) is a smaller component than carbon dioxide (CO2) but drives a more potent greenhouse effect. Researchers warn that efforts to tackle climate change will be undermined unless CH4 is also brought under tighter control. "CO2 is still the dominant target for mitigation, for good reason. But we run the risk if we lose sight of methane of offsetting the gains we might make in bringing down levels of carbon dioxide," said Robert Jackson from Stanford University, US. Prof Jackson was speaking ahead of this week's American Geophysical Union (AGU) meeting in San Francisco where methane trends will be a major point of discussion. "Methane has many sources, but the culprit behind the steep rise is probably agriculture," Prof Jackson told BBC News."We do see some increased fossil fuel emissions over the last decade, but we think biological sources, and tropical sources, are the most likely." Agricultural sources would include cattle and other ruminants, as well as rice paddies. Emissions from wetlands are almost certainly a significant part of this story as well. But so too could be the role played by the chemical reactions that normally remove methane from the atmosphere. One of the most important of these is the destruction process involving the so-called hydroxyl radical.The concentration of this chemical species in the atmosphere might also be changing in some way.Continue