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Floods, caused by global warming

The floods, caused by global warming

Floods in Australia REUTERS

CLIMATE - The latest studies show a link between the intensity of floods and global warming ... The

warming has increased the intensity of heavy rains and flooding in the northern hemisphere during the second half of the 20th century, according to research published Wednesday. Two studies appearing in the British scientific journal Nature among the first establishing a direct link between climate change and its impact on extreme weather events. Until then, this relationship remained largely theoretical, although numerical simulations predicted that rising greenhouse gas emissions in the atmosphere would aggravate the episodes of torrential rains. "It's really the case, our paper provides the first specific evidence," says Francis Zwiers (University of Victoria, Canada), co-author of one study. "Man influences the intensity of extreme precipitation events" , "he told reporters during a telephone press conference.

More water in the air when the weather warms

data collected in Europe, Asia and North America show that on average, more severe precipitation peaks with a duration of 24 hours in a given year had increased intensity during the latter half of the 20th century. When comparing these peaks with annual simulations of climate models, human influence becomes evident, according to Francis Zwiers. "The change can not be explained by natural fluctuations, the only internal climate system," he said. There is more water in the air when the weather warms up "the atmosphere has increased capacity to retain moisture," he says.
precipitation will not necessarily increase in regions where rainfall is low. Some may, instead, to become drier. "But this means that when precipitation occurs, there is more water," says this scientist.

risks of extreme rainfall doubled

Why was it so difficult for scientists to establish a direct link between climate change and extreme weather events? It is "easier and easier to detect in the comments" the effects of climate change as and greenhouse gas emissions accumulate in the atmosphere, "he says. Capabilities limited computational computers, however, remain an obstacle to achieve thin models and compare them to reality.
To overcome this obstacle, Myles Allen (Oxford University) and Pardeep Hall (ETH Zurich) have used the power of social networks to complete the second study on the impact of global warming in England, where Fall 2000 was marked by torrential rains causing severe damage. "We asked members of the public worldwide to leave their own personal computer simulations to make when we were not using it" he recounts. The distributed computing project climateprediction.net currently receives 50,000 to 60,000 personal computers.
The researchers were able to compare two numerical models, one based on detailed historical weather data, the other on a simulation of what would have happened in the fall of 2000 in England if greenhouse gas emissions n had not been issued in the 20th century. After repeating the simulation thousands of times, they found that these emissions had doubled the risk of seeing produce extreme rainfall events.