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 on February 17. 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.
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