Spread the Word

Increased flood risk linked to global warming.

by Nature News:

The effects of severe weather — such as these floods in Albania — take a huge human and financial toll.

Climate change may be hitting home. Rises in global average temperature are remote from most people’s experience, but two studies in this week’s Nature1,2conclude that climate warming is already causing extreme weather events that affect the lives of millions. The research directly links rising greenhouse-gas levels with the growing intensity of rain and snow in the Northern Hemisphere, and the increased risk of flooding in the United Kingdom.

There is no doubt that humans are altering the climate, but the implications for regional weather are less clear. No computer simulation can conclusively attribute a given snowstorm or flood to global warming. But with a combination of climate models, weather observations and a good dose of probability theory, scientists may be able to determine how climate warming changes the odds. An earlier study3, for example, found that global warming has at least doubled the likelihood of extreme events such as the 2003 European heatwave.

More-localized weather extremes have been harder to attribute to climate change until now. “Climate models have improved a lot since ten years ago, when we basically couldn’t say anything about rainfall,” says Gabriele Hegerl, a climate researcher at the University of Edinburgh, UK. In the first of the latest studies1, Hegerl and her colleagues compared data from weather stations in the Northern Hemisphere with precipitation simulations from eight climate models (see page 378). “We can now say with some confidence that the increased rainfall intensity in the latter half of the twentieth century cannot be explained by our estimates of internal climate variability,” she says.

The second study2 links climate change to a specific event: damaging floods in 2000 in England and Wales. By running thousands of high-resolution seasonal forecast simulations with or without the effect of greenhouse gases, Myles Allen of the University of Oxford, UK, and his colleagues found that anthropogenic climate change may have almost doubled the risk of the extremely wet weather that caused the floods (see page 382). The rise in extreme precipitation in some Northern Hemisphere areas has been recognized for more than a decade, but this is the first time that the anthropogenic contribution has been nailed down, says Oppenheimer. The findings mean that Northern Hemisphere countries need to prepare for more of these events in the future. “What has been considered a 1-in-100-years event in a stationary climate may actually occur twice as often in the future,” says Allen.

Nature News

London was first in implementing the Industrial Revolution now, they may be the first in implementing the Climate Change revolution as this is the first study in its kind to directly link flood risk to global warming. Let’s just, hope it’s not the last.