Two studies published in Nature this week have demonstrated a direct link between rising greenhouse gas levels and severe rainfall events.
Scientists compared rainfall predictions from eight climate models with data from weather stations around the Northern Hemisphere. Gabriele Hegerl, a climate researcher at the University of Edinburgh, United Kingdom, told NatureNews:
"We can now say with some confidence that the increased rainfall intensity in the latter half of the 20th century cannot be explained by our estimates of internal climate variability."
In the second study, scientists found that human greenhouse gas emissions "significantly increased" the likelihood of severe floods that caused £1.3 billion (US$2 million) of damage in England and Wales in 2000.
They showed, with a 66 per cent confidence level, that the emissions nearly doubled the risk of the 2000 floods. For comparison, the chances that emissions raised the risk of flooding by only a fifth are just 10 per cent.
"This has immense importance not just as a further justification for emissions reduction but also for adaptation planning," said Michael Oppenheimer, a climate policy researcher at Princeton University in the United States.
Similar attribution studies are underway for flood and drought risk in Europe; meltwater availability in the western United States; and drought in southern Africa, said NatureNews.
(1) Nature doi:10.1038/nature09763 (2011)
(2) Nature doi:10.1038/nature09762 (2011)