Dramatic rises in atmospheric methane are threatening to derail plans to hold global temperature rises to 2C, scientists have warned. In a paper published by the American Geophysical Union, researchers say sharp rises in levels of methane - which is a powerful greenhouse gas - have strengthened over the past four years. Urgent action is now required to halt further increases in methane in the atmosphere, to avoid triggering enhanced global warming and temperature rises well beyond 2C. “What we are now witnessing is extremely worrying,” said one of the paper’s lead authors, Professor Euan Nisbet of Royal Holloway, University...