Increased methane in the atmosphere – what is the cause?

For the past ten years methane levels have remained rather stable, while carbon dioxide levels have risen. Now it seems that methane levels are on the rise, especially around the Arctic region.

Methane, you will remember is a greenhouse gas which is about forty times more potent than carbon dioxide but fortunately it is no where near as long lived in the atmosphere as the dreaded CO2. Methane is present in very small quantities, measured in nanomoles per parts billion (carbon dioxide is measured in parts per million) but so potent is it that it is estimated to be responsible for 20% of the greenhouse gas direct radiative forcings. Currently methane is in the air at around 1770 parts per billion although the concentration varies according to latitude. Continue reading