Thursday, August 26, 2010

Time to blame climate change for extreme weather?

An editorial by Anil Ananthaswamy in New Scientist: It is time to start asking the hard questions. Countless people in flood-stricken Pakistan have lost families and livelihoods. Who can they hold responsible and turn to for reparations?

Less than a decade ago, these questions would have been dismissed outright. "Many scientists at the time said that you can never blame an individual weather event on climate change," says Myles Allen of the University of Oxford. But a small meeting of scientists in Colorado last week - organised by the US National Oceanic and Atmospheric Administration, the UK Foreign and Commonwealth Office and the UK Met Office's Hadley Centre, among others - suggests the tide is turning.

The aim of the Attribution of Climate-Related Events workshop was to discuss what information is needed to determine the extent to which human-induced climate change can be blamed for extreme weather events - possibly even straight after they have happened.

…The basic idea in producing such a figure is straightforward. Run thousands of simulations of the climate as it is and as it would have been without human influences, then compare the number of times a given event occurs in each scenario. In 2004, technological limitations made it impossible to run simulations for long enough to reproduce the 2003 heatwave, so the analysis involved making certain assumptions.

…Ultimately, though, putting numbers on the consequences of climate change will open the door to legal challenges. "There is a possibility that people who are adversely affected by climate change might seek compensation from those they feel are responsible," says Allen.

…There is another reason for finding out how much climate change is to blame for various events. "Hundreds of billions of dollars are potentially available [in a UN fund] to help developing countries adapt to climate change," says Allen. Who gets what share of the funds depends on being able to say which regions have suffered most as a result of climate change. For now, at least, that remains an open question….

Hurricane Mitch in 1998

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