The biggest computer calculation of its kind has forecast a degree of global warming greater than previously predicted that could turn Britain into an unrecognisable tropical country in a few generations.

The forecast, which was computed by the Intergovernmental Panel on Climate Change, estimated a rise in the average global temperature of 11 degrees Celsius, causing ice caps to melt, according to the daily Scotsman.

Because climate change affects latitudes away from the equator the most, temperatures in Britain could rise by as much as 20 degrees Celsius, changing the face of the country and the lives of its inhabitants, the study said.

The new experiment in climate modelling based on current policies and recommendations on a warming range of two to five degrees Celsius is called climateprediction.net.

It uses the spare processing capacity of thousands of computers.

Over 95,000 people from 150 countries, including schoolchildren, university students and office workers, contributed to the research by downloading the free software.

David Stainforth of Oxford University, the leader of the research, said: "An 11-degree-warmed world would be a dramatically different world.

"With a world warmed by 11 degrees there would be large areas of high latitude that could be 20 degrees warmer than they are today.

"Britain would be at the high end of this change, well into the teens as the temperature changes. I don't think we'll be building many snowmen in winter or going sledging."