By Alex Kirby, BBC News Online environment correspondent and presenter of Costing the Earth

Scientists in the US believe hurricanes may become more powerful in the next few decades, and that the damage they cause will be much greater.

Dr Chris Landsea, of the hurricane research division of the National Oceanic and Atmospheric Administration (NOAA), told BBC Radio Four's environment programme Costing the Earth how serious the problem might become.

He said he now thought that global warming would not cause more frequent and intense hurricanes, but that a natural cycle could produce the same result.

"Our best estimates now are that the frequency of hurricanes won't change much at all, and that the intensities may go up by five or 10%.

Damage doubled

"If we did see a 10% increase in the strength of the strongest hurricanes, that might mean 50% more damage, or doubling the damage. That is a magnitude that's worth worrying about."

A colleague of Dr Landsea's, Professor Hugh Willoughby, specialises in trying to reduce the power of hurricanes.

He told the programme, which reports on the increasing incidence of abnormally severe weather, that one possible way would be to spray a layer on the ocean surface to interfere with evaporation. But the spray would have to be capable of withstanding wind speeds of 50 metres per second.

Professor Willoughby said most people who sent him ideas failed to appreciate a hurricane's size and power.

"A hurricane generates mechanical energy at a rate comparable with all of the electrical power generation that the human race uses.

"In other words, there's more mechanical energy in a hurricane than you could get if you hooked all of the generating plants in the world together."

The programme also visited the island of Kutub Dia, a few miles off the coast of Bangladesh in the Bay of Bengal, which was devastated by a cyclone and tidal surge in 1991.

Of the island's population of almost 120,000 people, 30,000 were killed when the water completely submerged it.

No money to save more

Kutub Dia now has a string of 24 cyclone shelters, each able to accommodate about 2,000 people. But that still leaves half its people unprotected.

The Bangladeshi environment minister, Mrs Sajeeda Choudhury, told Costing the Earth her government had no money to build more shelters. And she said it would take another seven years to complete the raising of the embankment which protects the island against tidal surges.

The programme also says the United Kingdom is not immune from the rise in extreme weather.

Peter Midgley of the Environment Agency is responsible for sea defences along the Sussex coast in southern England. He told Costing the Earth there was a growing risk to life.

"In the past, we felt it would be less than once in every lifetime that you'd see a serious flood which could cause real damage and potential loss of life.

"I think given the way things are going, with sea levels rising and increasing storminess, it might be that in 40 or 50 years' time you'd be seeing one, two or possibly three floods of that sort of magnitude within a lifetime.

"Lives certainly are at risk. The last serious coastal flooding we had was in the early fifties on the east coast of England, with well over 200 deaths.

"The risk is there, it could easily happen, and you could get even greater casualties."