The role of methane in the atmosphere has been emphasized by the IPCC to the point that many governments regard methane as almost as important as carbon dioxide amongst the greenhouse gases. The result is that emissions from natural gas pipelines, coal seams and agricultural livestock have been included in schemes to limit the growth of greenhouse gas concentrations. Analysis of changes to atmospheric methane within the last one hundred years suggests that the annual increases from 1930 to 1990 were due to losses from the production, transmission and distribution of natural gas that have now been reduced. Measurements over the last fifteen years show only natural variability. The data provide no justification for any attempts to reduce methane from industrial or agricultural activity.
For a full report by Tom Quirk, Twentieth Century Sources of Methane in the Atmosphere, see: http://carbon-sense.com/wp-content/uploads/2011/01/quirk-methane-in-atmosphere.pdf [PDF, 223 KB]