He also said people are more likely to act if they are given positive messages about what they can do.

“All the evidence shows you should be measured in showing people the risk but you can also be clear about the actions they can take. Scaring them will just put them off,” he added.

A separate study by the Carbon Trust found that more than half of people in Britain want big business to be more responsible when it comes to cutting greenhouse gas emissions.

However just seven per cent believe public announcements from a company about how it is reducing its impact on climate change are accurate

This week a number of initiatives to cut carbon are being held around the country for Climate Week, a nationwide event sponsored by Tesco and supported by Al Gore and Sir Paul McCartney.

The idea is to celebrate the positive things people can do to cut carbon emissions such as saving energy at home and taking public transport.

However campaigners say that some of the companies involved have failed to do enough to tackle climate change.

The World Development Movement claim that one of the main sponsors, the Royal Bank of Scotland, has invested more in coal-fired power stations than any other UK bank over the last few years.