BBC: Levels of the greenhouse gas methane in the atmosphere seem to be rising having remained stable for nearly 10 years. Data from the National Oceanographic and Atmospheric Administration (Noaa) in the US suggest concentrations rose by about 0.5% between 2006 and 2007. The rise could reflect melting of permafrost, increased industrialisation in Asia or drying of tropical wetlands. The rise in carbon dioxide levels was significantly higher than the average annual increase …