Greenhouse gases contributed substantially to the risk of floods in Autumn 2000
17 February 2011
Greenhouse gas emissions due to human activity substantially increased the odds of damaging floods occurring in England and Wales in Autumn 2000 according to new research published in the journal Nature this week. Although the precise magnitude is still uncertain, the researchers found a 2-in-3 chance that the odds were increased by about a factor of two or more.
The floods of autumn 2000 damaged nearly 10,000 properties, with insured losses estimated at £1.3 billion. The study suggests that, although these floods could have occurred in the absence of human influence on climate, greenhouse gas emissions can now be blamed for increasing the odds of floods occurring at that time.
Dr Pardeep Pall, who initiated the research as a Doctoral student at Oxford University’s Department of Physics, said: ‘This study is the first of its kind to model explicitly how such rising greenhouse gas concentrations increase the odds of a particular type of flood event in the UK, and is the first to use publicly volunteered computer time to do so.’
Using a detailed computer climate model, developed at the Met Office Hadley Centre, the project team simulated the weather in Autumn 2000, both as it was, and as it might have been had there been no greenhouse gas emissions since the beginning of the 20th Century. This was then repeated thousands of times using a global volunteer network of personal computers participating in the climateprediction.net project in order to pin down the impact of emissions on extreme weather.
In collaboration with Risk Management Solutions (RMS), developers of risk models for the insurance industry, the team then fed the output from these weather simulations into a flood model, and found that 20th-Century greenhouse gas emissions very likely increased the chances of floods occurring in Autumn 2000 by more than 20%; and likely by 90% (close to doubling the odds) or more.
Dr Dag Lohmann of RMS, a co-author on the paper, said: ‘studies like this are helpful, since we need to know how risks are changing to provide our clients with accurate models of risk today.’
Dr Peter Stott, of the Met Office, also a co-author, said: ‘This study is the first step toward near real-time attribution of extreme weather, untangling natural variability from man-made climate change. This research establishes a methodology that can answer the question about how the odds of particular weather events may be altering. It will also allow us to say, shortly after it has occurred, if a specific weather event has been made more likely by climate change, and equally importantly if it has not.’
Dr Richard Harding, of CEH Wallingford and the coordinator of the EU WATCH project which co-funded this research, said ‘climate change is only one of many factors affecting local flood risk, but understanding it is clearly important if we are to plan how to adapt.
’Professor Myles Allen, of Oxford University’s Department of Physics and School of Geography and the Environment, a co-author of the paper, said: ‘whether or not a flood occurs in any given year is still an ‘Act of God’ but, with the help of thousands of climateprediction.net volunteers, we are beginning to see how human influence on climate may be starting to load God’s dice.’
Members of the public can still participate in follow-up studies, supported by Microsoft Research, Oxford University’s Smith School for Enterprise and the Environment, the Met Office, and the Natural Environment Research Council, to assess how emissions might have changed the odds of a whole host of weather-related events – including floods and droughts – in regions across the world: more details at http://weatherathome.org. The Met Office Hadley Centre has been commissioned by DECC, Defra and DfID to work with international partners as part of the Attribution of Climate-related Events Group: developing the science of attribution of extreme weather that will be needed to provide regular and scientifically robust assessments of how the odds of these phenomena are changing.
For more information contact Professor Myles Allen of Oxford University on mobile; +44 (0)7776 306691 or email myles.allen@physics.ox.ac.uk or Dr Pardeep Pall, now based at ETH Zurich, on +41 44 632 33 64 or email pardeep.pall@env.ethz.ch or Dr Peter Stott, at the Met Office on +44 (0)1392 886655
Alternatively contact the University of Oxford Press Office on +44 (0)1865 283877 or email press.office@admin.ox.ac.ukOr the UK Met Office Press Office on +44 (0)1392 886655 or email pressoffice@metoffice. gov.uk