To ask the Secretary of State for Environment, Food and Rural Affairs what recent estimate she has made of the quantity of methane which is being released annually by the northward retreat of permafrost and the consequent impact on climate change. 
[holding answer 30 June 2003]: Methane concentrations have increased by a factor of 2.5 since pre-industrial times and account for about 20 per cent. of the climate warming due to greenhouse gases. The increase in concentration is mostly due to increases in anthropogenic emissions (from sources such as landfills, energy production and biomass burning). We have no estimates for the current annual release rate from such areas but methane emissions from high-latitude permafrost areas are likely to have made a contribution to climate change due to greenhouse gases of less than 1 per cent.