A mysterious rise in methane levels is sparking warming fears. Whatever the cause, methane levels have raced ahead of most climate scientists’ scenarios. Even new modelling for a landmark report by the Intergovernmental Panel on Climate Change, due out in August, predicts that methane concentrations will start to fall this year, says Martin Manning at the Victoria University of Wellington, New Zealand. But that isn’t happening in reality. Some research has blamed the US fracking boom, which coincided with the rise in methane. However, the methane in air flasks that Michel’s lab has sampled in recent years has less carbon-13 and more carbon-12, implying the growth is from microbial sources such as wetlands and agriculture. “Fossil fuels are definitely part of the picture. But it’s hard to explain our data without having an increase in biogenic methane,” says Michel.
New Scientist 18th May 2021 read more »