Age: ATMOSPHERIC concentrations of methane, “a greenhouse gas more than 20 times more potent than carbon dioxide”, have risen for the first time in eight years, prompting concern about the pace of climate change. A global study in Geophysical Research Letters found the first increase in methane levels this century — by about 28 million tonnes since mid-2006 — was in part due to release of gas in and near the Arctic. CSIRO senior climate scientist Paul Fraser said the data was in …