Man-made climate change increased the risk of severe storms that led to devastating flooding in the south of England in the winter of 2013/14, scientists have said.
Researchers at Oxford University found that anthropogenic greenhouse gas emissions increased the risk of the once-a-century wet January in 2014 by 43%.
The worst-affected areas 2013/2014
Among the worst-affected areas were Somerset, Devon, Dorset and Cornwall in the south west, and the Thames Valley in the south east.
According to the scientists' analysis, the increase in rainfall that led to the flooding was the result of two factors associated with global warming:
An increase in the water-holding capacity of the atmosphere (a thermodynamic factor)
More January days with westerly air flow (a dynamic factor)
Approximately two-thirds of the increased risk could be attributed to thermodynamic changes in the atmosphere and one-third to dynamic changes, the researchers found.
How the analysis was carried out
The research made use of the weather@home citizen-science project,which is part of Oxford's climateprediction.net climate modelling experiment.
It modelled possible weather for January 2014 in both the current climate and one in which there was no human influence on the atmosphere.
simulations of possible rainfall in the UK were analysed by researchers.
Lead author Dr Nathalie Schaller of Oxford University's Department of Physics said the "extreme rainfall" is more likely to occur in a "changing climate".
We found that extreme rainfall, as seen in January 2014, is more likely to occur in a changing climate. This is because not only does the higher water-holding capacity lead to increased rainfall, but climate change makes the atmosphere more favourable to low-pressure systems bringing rain from the Atlantic across southern England.