METHANE, a key greenhouse gas that has been growing alarmingly in the atmosphere, suddenly stopped in its track beginning 1992. Although previous studies had shown that the rate of methane increase slowed down in the '80s, a new analysis carried out by Edward Dlugokencky of the US's National Oceanic and Atmospheric Administration found that since mid-'92, the rate of increase has plunged in the southern hemisphere and crashed to near zero in the northern hemisphere (Science, Vol 263, No 5148). Some link the decrease to leaks plugged in natural gas pipelines in Russia, but others fear that nature is up to some mischief that scientists are yet to recognise.