ClimatePrediction.net and Weather@Home
The world’s largest climate experiment
Climate models predict significant changes to the Earth’s climate in the coming century, but the predictions range greatly, signifying high levels of uncertainty. Creating better models requires vast amounts of computing power. By using a screensaver running on people's home and work computers across the world, ClimatePrediction.net is able to combine the power of thousands of ordinary computers, each tackling one small but key part of the global problem.
By using a distributed network of computers, the project aims to improve our understanding of, and confidence in, climate change predictions, far more effectively than would ever be possible using even the best supercomputers currently available to scientists.
With high uncertainty, there is an increased probability that the models may over-estimate or under-estimate the speed and scale of climate change. If the models over-estimate it, we may invest huge amounts of money trying to avert a problem which isn’t as serious as the models suggest. Alternatively, if the models under-estimate the change, we will end up doing too little, too late in the mistaken belief that the changes in weather patterns will be small and gradual. To cope with this problem, we need to quantify the uncertainty in these predictions.
There are two complementary approaches to assess and reduce uncertainty:
- Improve the parameterisations while narrowing the range of uncertainty in the parameters. This continuous process requires:
i) Improving the models by using the latest supercomputers as they become available.
ii) Gathering more and more (mainly satellite) data on a wide range of atmospheric variables (such as wind speed, cloud cover, temperature).
- Carry out large numbers of model runs in which the parameters are varied within their current range of uncertainty. Reject those which fail to model past climate successfully and use the remainder to study future climate.
The second approach is the one taken by climateprediction.net. Our intention is to run hundreds of thousands of state-of-the-art climate models with slightly different physics in order to represent the whole range of uncertainties in all the parameterizations. By running the model thousands of times, we hope to find out how sensitive individual models are to small disturbances, as well as to changes in carbon dioxide and sulphates in the atmosphere. Whilst these tweaks are slight enough not make the approximations any less realistic, they allow us to explore how climate may change in the next century under a wide range of different scenarios.