100,000 PCs Involved In Climate Predicting Experiment

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Early results from climateprediction.net suggest that the climate could be a lot more sensitive to greenhouse gases and could warm a lot more than the Intergovernmental Panel on Climate Change (IPCC) has previously suggested. These and future results will form part of the UK's contribution to the fourth report of the IPCC due in 2007. 'Better assessment of the uncertainties in climate forecasts is a priority for the Met Office and the Government. The climateprediction.net experiment should give policy-makers a better scientific basis for addressing one of the biggest potential global problems of the twenty-first century', says Mat Collins of the Met Office.

Climate change and our response to it are issues of global importance, affecting food production, water resources, ecosystems, energy demand and insurance costs. There is a broad scientific consensus that the Earth will warm over the coming century, but the key question is by how much? Climateprediction.net should, for the first time, allow scientists to give a much more complete answer to this question.

Best estimates of future climate change come from general circulation models (GCMs), which are the same models used to make everyday weather forecasts. GCMs simulate as much as possible about the climate system: the incoming and outgoing radiation, the way the air moves, the way the ice sheets grow or shrink and how all these different parts of the climate system interact and affect each other. A limiting factor in developing accurate models has been the time that even the most powerful computers take to repeatedly run models with slight variations in all these interacting factors. Climateprediction.net has overcome this problem by harnessing the combined power of tens of thousands of PCs worldwide, making it the world's largest and most complete climate-modelling experiment.

General circulation climate models are now running on over 100,000 PCs in locations as far afield as Nicaragua and Nepal. Individuals participate by downloading and running a unique simulation of the Earth's climate. These models are tested to see if they can accurately simulate past and present climates, and are then used to predict the future climate. 'Thanks to chaos theory, we can't predict which versions of the model will be any good without running these simulations, and there are far too many for us to run them ourselves. Together, participants' results from around the world will give us an overall picture of how much human influence has contributed to recent climate change and of the range of possible changes in the future', says Myles Allen, principal investigator at climateprediction.net.

The idea of using the combined power of personal computers is not new. SETI @ home, with the help of several million people, has been processing radio telescope data for signs of extra-terrestrial life since 1999. A key factor in the development of the climateprediction.net project has been the dramatic increase in computing power of home PCs. 'Five years ago it would have been unthinkable to run a complete climate model on a home computer', explains Sylvia Knight, Communications Manager for the project.

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