Dr Myles Allen from the Rutherford Appleton Laboratory, England, says that if enough people join forces worldwide to analyse data, it might be possible to get an accurate prediction of what the planet's climate might be like in 50 years' time.
More than a million volunteers are currently involved in a similar scheme which uses screensaver software to scan radio-telescope data for signs of extraterrestrial intelligence.
The SETI@Home project has been a phenomenal success and is credited with being the largest computation ever done.
But Dr Allen believes using the desktops to model the Earth's climate would represent a more practical application of all that PC power.
"After all, it is possible that none of the participants in the SETI@home project will find signals of alien life," he writes in the science journal Nature.
"But, provided we keep the records, someone could definitely tell their grandchildren that it was they who, on a cheap PC, made the most accurate forecast of the global mean temperature of 2050."
Scientists currently use the world's fastest supercomputers in an attempt to forecast what the climate might be like on planet Earth well into the next century.
But even these machines struggle with the number of calculations that are required to build up what might be regarded as a "realistic" picture of events.
Complex interactions
They have to incorporate a multitude of complex interactions, including cloud formation, precipitation, oceanic heat transport and sea-ice formation. Many measurements have to be averaged otherwise the computing task would simply be impossible.
The Casino-21 Climate Simulation project will effectively allow the number of these measurements to be increased and tested. This, hopefully, will improve the "accuracy" of the simulations and help humankind formulate a practical response to the problems that may stem from an increase in CO2 and other greenhouse gases.
"PCs, often driven by the needs of games, have really developed very fast," Dr Allen told BBC News Online.
"It's now possible to run climate models, which we wouldn't have dreamt of running on anything other than a supercomputer a few years ago, on something people have in their bedrooms."
Computer users can register to take part in the project at a special Website set up by the Rutherford Lab. The screensaver software can be downloaded over the Net or requested on a CD.
The program will run a model that will attempt to match what has happened to the climate over the past 50 years and, if it succeeds, produce a climate forecast that runs into the next century.
Dr Allen hopes the project will fire the imagination of the public and inform them about the uncertainties associated with climate prediction.
"Climate prediction is not an exact science," he said. "You can only say there is a range of possibilities and this is, arguably, with a chaotic system, one of the only ways of pinning down that range.
"People who join the project will be contributing to a better understanding of what the risks are from climate change."
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