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Agriculture, Not Fuel, Is Behind Rising Methane

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Increasing levels of methane in the atmosphere since 2007 are most likely due to agricultural practices, and not fossil fuel production as previously thought, according to research published in Science (www.tinyurl.com/zmu4wcn).

Methane levels in the atmosphere are estimated to have risen by about 150% since 1750, but levels plateaued between 1999 and 2006. Since then methane levels have been rising again.

Scientists at New Zealand’s National Institute of Water and Atmospheric Research first noticed these trends in the data collected at monitoring stations in Wellington and Antarctica. With only Southern Hemisphere data to go on, the scientists collaborated with American and German researchers who were taking similar measurements in a number of locations across the world.

“We found we could distinguish three different types of methane emissions,” said Dr Hinrich Schaefer. “One is the burning of organic material, such as forest fires. Another is fossil fuel production – the same processes that form natural oil and gas – and the third is formed by microbes which come from a variety of sources such as wetlands, rice paddies and livestock.”

Around the time the plateau in methane emissions occurred, economic collapse in the Soviet Union reduced oil production dramatically,...

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