Carbon offsetting 'can be harmful'

People who join the new fashion for buying carbon offsets will be urged by the Government today to check what they are buying before they hand over the money. Some schemes may be doing environmental damage in the developing world without curbing climate change.

The Environment Secretary, David Miliband, is to announce the start of a government consultation that will make the UK the first country with a national standard for testing carbon offset schemes. Mr Miliband is expected to warn consumers to be wary of offset schemes involving tree planting, and to direct their money instead into "win-win" projects such as a scheme to generate electricity from pig droppings in Mexico.

Carbon offset schemes are supposed to nullify the effect of carbon emissions in one part of the world, by investing in developments which reduce carbon emissions elsewhere, or which take carbon out of the atmosphere.

Last year, the Government promised to offset every air mile travelled by ministers or civil servants on official business, by buying two tons worth of offsets for every ton of carbon emitted.

But environmentalists fear that big polluters will turn to buying offsets to ease their consciences, instead of cutting air miles. The head of Greenpeace's energy campaign, Charlie Kronick, said: "The scientists warn we need to slash our carbon emissions, but there is a risk that the fashion for off-setting could actually encourage people to take unnecessary journeys."

Environmentalists also question the value of some of the schemes being sold by private companies. Large-scale tree planting can damage the environment and livelihoods in the Third World, especially where there is no variety in the species of tree being planted. "Buying forestry offsets does nothing to lessen society's dependence on fossil fuels, something that is ultimately needed to address climate change," said Kirsty Clough, of the World Wildlife Fund.