Letter: Action without proof

Sir: Roger Bate, director of the environment unit at the Institute of Economic Affairs, misses the point when he says there is not sufficient proof to link carbon dioxide emissions to global warming ('Green tax on fossil fuels 'unwarranted' ', 4 April). Presumably he would also advocate doing nothing about lead in petrol or to control levels of pesticides in foodstuffs because there is no 'proof' that these are harmful to health. In both such examples science cannot 'prove' anything - it can only present a balance of probabilities.

The evidence, as judged by the vast majority of scientists working on the issue, is overwhelmingly in agreement that human interference in the climate is occurring. Uncertainty there may be, but it cuts both ways. If there is a small possibility that climate change is anything to worry about, there is similarly a small possibility of a catastrophic 'runaway' greenhouse effect, the consequences of which are likely to be second only to those of global thermonuclear war.

Failing to act on the basis of inevitable scientific uncertainty legitimises continued inefficient use of fuel and resources, and allows government to set a poor regulatory, fiscal and informational framework for promoting good practices.

Yours sincerely,

DOUG PARR

Head of Science, Greenpeace

London, N1