Researchers from Sweden’s Linköping University say emissions of greenhouse gases from natural sources will increase during global warming, with the result that climate change will progress at faster-than-expected rates. “Everything indicates that global warming caused by humans leads to increased natural greenhouse gas emissions,” says Sivakiruthika Natchimuthu, a doctoral candidate at the university and the lead author of a paper that studied methane gas emissions from three lakes. The team found that emissions increased exponentially as temperatures rose. With an increase in temperature of 15 to 20 degrees celsius, methane levels nearly doubled. “This means that warming will be faster than expected from anthropogenic greenhouse gas emissions alone,” says a release from the university.