Twentieth Century Sources of Methane in the Atmosphere

Abstract

The role of methane in the atmosphere has been emphasised by the IPCC to the point that many governments regard methane as almost as important as carbon dioxide amongst the greenhouse gases. The IPCC emphasis has resulted in emissions from natural gas pipelines, coal seams and agricultural livestock being 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 1970 were due to losses from the production, transmission and distribution of natural gas. Further, the substantial reduction in these losses from 1970 to 1990 has brought the annual increases back to the rate seen at the start of the twentieth century. Measurements over the last fifteen years show only natural variability. They provide no justification for any attempts to reduce methane from industrial or agricultural activity. While methane variability remains restricted to natural causes, the best policy is to do nothing.