We seem to know less about methane emissions than we thought. After a decade of stability, methane concentrations in the atmosphere have been rising strongly in the last 18 months. Early research work suggested that this rise was concentrated in the northern latitudes of the northern hemisphere and was consistent with greater emissions from decaying organic matter in melting permafrost or from the melting of Arctic sea ice. Now this result has been called into question by the publication of a new study showing the concentrations of methane are rising almost everywhere. Since methane takes some time to diffuse around the globe, the later work suggests that the rise in methane may not be directly due to enhanced emissions from biological sources.