The chairman of the Royal Commission on Environmental Pollution, Sir John Lawton, has called climate change deniers in the US "loonies", and says global warming is to blame for the increasingly strong hurricanes being spawned in the Atlantic.

In an interview with The Independent, Lawton said that global warming is "very likely" the cause of increasingly intense hurricanes, in line with computer simulations.

He told the paper: "If this [the arrival of Hurricane Rita] makes the climate loonies in the States realise we've got a problem, some good will come out of a truly awful situation."

Lawton was speaking as Hurricane Rita is growing in strength in the Gulf of Mexico and the region prepares for another battering.

NASA has closed the Johnson Space Center in Houston in preparation for the storm, and has evacuated personnel from sites damaged by Katrina. At the Michoud Assembly Facility, a skeleton crew of just forty remains to ride out the storm.

Meanwhile, residents of Houston are evacuating the city. Traffic queues hundreds of kilometres long are forming as fears grow that Houston could suffer the same kind of onslaught that caused such devastation in New Orleans last month.

Lawton said that with two such large storms hitting the Gulf coast in such quick succession, the Bush administration should re-evaluate its position on climate change. He said if the "extreme sceptics" in the US could be persuaded to change their minds, that would be "a valuable outcome [of] a horrible mess".

"There are a group of people in various parts of the world ... 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."

Some climatologists maintain that global warming is unlikely to have an impact on hurricanes. They argue that the increase in landfalls we are seeing now is due to a long term (50-70 years) cycle in Atlantic ocean temperatures, a phenomenon known as the Atlantic Multidecadal Oscillation.

However, Sir John says that it is fair to conclude that an increasingly warm climate, caused at least in part by human activity, is also warming the oceans' surfaces, and increasing the violence of hurricanes.

"Increasingly it looks like a smoking gun," he said. ®