Britons must swap their wasteful habits with food for the thrifty approach of previous generations by buying less and eating leftovers if the UK is to play its part in averting climate change, shoppers were warned yesterday. The call for a "cultural" move against overshopping was made by Joan Ruddock, the Environment minister, after research showed Britons threw away one third of their food, at an enormous hidden financial and environmental cost.

Annually, the UK dumps 6.7 million tonnes, meaning each household jettisons between £250 and £400 worth of food each year. Most of the waste – which nationally costs £8bn – is sent to landfill where it rots, emitting the potent climate- change gas methane.

Ms Ruddock, the minister for climate change, warned that, although many people had not made the connection between scraping food into the bin and climate change, waste food presented a bigger environmental problem than packaging. "We cannot fail to do what is necessary," she said. "At this rate we will not have a place to live which is habitable if we don't address climate change globally and the UK has to make its contribution."

The Waste & Resources Action Programme (Wrap), a government-funded agency that has been investigating food waste, complained consumers were, in effect, dumping one in three bags of shopping straight in the bin. Preventing that waste would have the same environmental impact as taking one in five cars off the roads, said Wrap's chief executive, Liz Goodwin.

In an attempt to change attitudes, Wrap has devised a campaign "Love Food Hate Waste", launched at Borough Market in London yesterday by Ms Ruddock and the TV chefs Ainsley Harriott and Paul Merrett. A slew of prominent chefs including Tom Aikens and Mark Hix, the former cricketer David Gower and the actress Prunella Scales are backing an advertising blitz that encourages people to plan their shopping, use food before it goes off and make meals from leftovers.

Appearing on the campaign's video, the Hell's Kitchen chef Marco Pierre White recalled that his mother used to make bubble and squeak out of leftovers and called for people to return to more careful ways. "There's a use for everything. We should show a little more respect for Mother Nature," he said.

Wrap's estimate of waste was compiled after polling almost 3,000 households and getting 300 people to keep diaries of what food they threw away. Although 90 per cent of people thought they threw away little, the true picture was revealed by the diaries.

Most waste arose because people had "over-shopped" as a result of not planning; because they failed to keep their fridge cold enough, allowing food to go off; or because food had passed its "best by" date. About 30 per cent of households were particularly wasteful, mostly busy younger working people aged 16-34 and families with school-age children.

Wrap said people were buying too much, particularly because they were temped by "buy one get one free" deals in supermarkets. Shoppers also failed to eat food in date order, store it at the right temperature or throw it out as it approached its best-before date. Young professionals with fluid work and social patterns seldom planned meals. Wrap said half of people under 24 had very poor cooking skills, possibly as a result of the emphasis in schools on the science of food.

(By Martin Hickman, The Independent, 02/11/2007)