Daily Telegraph: Atmospheric levels of the greenhouse gas, which is as much as 60 times more potent than carbon dioxide, appear to have risen significantly for the past three years running, scientists say. Experts have long feared that vast amounts of the natural gas trapped in the frozen tundra of the Arctic could be unlocked as the permafrost is melted by rising temperatures, triggering a “methane time bomb” that could cause temperatures to soar. More melting of the Arctic ice caused by …