Thousands of people from around the world volunteered their home computers to run a complex atmosphere-ocean climate model, enabling scientists to better forecast the impact of changing climate patterns. As a result of their efforts, scientists concluded that global warming of 3 degrees Celsius is possible. The study, presented in the journal Nature Geoscience, was supported in part by the EU-funded projects WATCH and ENSEMBLES. Both WATCH ('Water and global change') and ENSEMBLES ('Ensemble-based predictions of climate changes and their impacts') were funded under the ' Sustainable development, global change and ecosystems' Thematic area of the EU's Sixth Framework Programme (FP6) to the tune of EUR 9.98 million and EUR 15 million, respectively.
Scientists believe that this study, the first to run so many simulations using a complex atmosphere-ocean climate model, will address the uncertainties that have surfaced regarding previous forecasts that used simpler models or ran only a few dozen simulations.
The team concluded that a global warming of 3 degrees Celsius by 2050 is 'equally plausible' as a rise of 1.4 degrees. They noted that the forecast range is derived from models that accurately reproduce observed temperature changes over the last 50 years.
'It's only by running such a large number of simulations — with model versions deliberately chosen to display a range of behaviour — that you can get a handle on the uncertainty present in a complex system such as our climate,' said lead author Dr Dan Rowlands from the Department of Physics at the University of Oxford in the United Kingdom. 'Our work was only possible because thousands of people donated their home computer time to run these simulations.'
What the results suggest is that the possibility of the world crossing the '2 degrees barrier' this century is very likely if emissions continue unabated. This is important for other researchers who are planning for the impacts of climate change; with this information in hand, they now need to consider the possibility of warming of up to 3 degrees (above the 1961–1990 average) by 2050 even on a mid-range emission scenario. This is a faster rate of warming than most other models predict.
'Most forecasts of global warming are based on the range of results that different groups around the world happen to contribute to a model comparison,' said Professor Myles Allen from the School of Geography and Environment, University of Oxford, and one of the authors of the paper. 'These groups don't set out to explore the full range of uncertainty, which is why studies like ours are needed.'
Co-author Dr Ben Booth, senior climate scientist at the Met Office Hadley Centre, explained: 'There have been substantial efforts within the international community to quantify and understand the consequence of climate uncertainties for future projections. Perhaps the most ambitious effort to date, this work illustrates how the citizen science movement is making an important contribution to this field.'
The project brought together many actors from across Europe as well as private enterprise. More than 35 000 active hosts were used during this study. Volunteers ran a climate model on their computer. The model ran automatically as a background process on their computers whenever it was switched on. Users could use their computer as they wished without interference and results would be sent automatically.
Co-author Professor Dave Frame of Victoria University of Wellington in New Zealand, Visiting Fellow of Oxford's Smith School of Enterprise and the Environment, said: 'Ensembles like this are an innovative way of exploring a range of possible futures, and provide an exciting new resource for the climate adaptation and impact communities.'