Written question asked by Norman Baker (Liberal Democrat) on Monday, 13 February 2006, in the House of Commons. It was due for an answer on Wednesday, 15 February 2006. It was answered by Elliot Morley (Labour) on Wednesday, 1 March 2006 on behalf of the Department for Environment, Food and Rural Affairs.

Climate Change

Question: To ask the Secretary of State for Environment, Food and Rural Affairs what assessment she has made of the quantification of the relationship between global dimming and the measureable effect of climate change; and if she will make a statement.

Answer: It is not possible at this stage to quantify with accuracy the relationship between global dimming and climate change because of the large uncertainty in the magnitude of the cooling effect of sulphate aerosols, the main contributor to global dimming.A recent study funded by the Department, which was published in the journal Nature last December, suggested that the cooling effect of anthropogenic aerosols could be larger than previously estimated. If confirmed, these results suggest the likelihood of a larger impact of increasing CO2 emissions on the climate system, adding urgency to our need to cut greenhouse gas emissions.Estimating the size of the cooling resulting from aerosols is an ongoing and crucial research activity. The Department continues to fund research in order to determine the size of the aerosols' cooling effect and what overall implications there are for forecasts of future global warming.

Secondary information