Super-powerful hurricanes hitting the United States are the "smoking gun" of global warming, says one of Britain's leading scientists.
The growing violence of storms such as Katrina, which wrecked New Orleans, and Rita, now threatening Texas, was probably caused by climate change, said Sir John Lawton, chairman of the RoyalCommission on Environmental Pollution.
Hurricanes were getting more intense, just as computer models predicted they would, because of the rising temperature of the sea.
"The increased intensity of these kinds of extreme storms is very likely to be due to global warming."
In a thinly veiled attack on the Bush Administration, Sir John hit out at neoconservatives in the US who still deny climate change.
Referring to the arrival of Hurricane Rita he said: "If this makes the climate loonies in the States realise we've got a problem, some good will come out of a truly awful situation."
Asked about characterising them as "loonies", he said: "There are a group of people ... who simply don't want to accept human activities can change climate and are changing the climate.
"I'd liken them to the people who denied that smoking causes lung cancer."
A paper by US researchers in the journal Science last week, showed that storms of the intensity of Hurricane Katrina have become almost twice as common in the past 35 years.
During the same period, sea surface temperatures, among the key drivers of hurricane intensity, have increased by an average of 0.5C.
Sir John said: "Increasingly it looks like a smoking gun."
