"The insurance industry really is starting to take action" against global warming and its effects, he said at a conference on global warming at Rice University.

"US insurers have elected not to join in, often because they have close links to the fossil fuel industry," said Crichton, who is now a visiting professor at Benfield Hazard Research Centre at University College London.

Most experts say the Earth is becoming warmer because carbon dioxide is increasing in the atmosphere due to the burning of fossil fuels.

They warn the changing climate could cause many more severe storms, the submersion of coastal land, increased pollution and greater danger of mosquito-borne illnesses.

Crichton said more than 200 financial firms and insurers from around the world have signed on to the UN Environmental Program Financial Initiative aimed at promoting sustainable development and ameliorating problems such as global warming.

But only one US insurance firm and a handful of US banks signed up, Crichton said.

"It's really all the major banks and insurance companies in the world, except the USA.," he said. "In the USA., the fossil fuel companies are extremely powerful."

A large number of US energy firms, many of which are based in Houston, do not accept that man-made climate change is occurring. They say science has not yet proved it.

The United States is the largest emitter of greenhouse gases, but the Bush administration has refused to sign the international Kyoto Treaty to curb global warming.

Crichton spoke at a conference on climate change and its effect on coastal cities organized by the Shell (Oil) Center for Sustainability at Rice, the British government and University College London.

Several speakers detailed an ambitious program by London to curb greenhouse gas emissions and said other cities should do the same.

But in Houston, one of the world's oil capitals, opposition to the notion of global warming is so strong that local officials have to be careful not to use the term, said Elena Marks, the city's director of health policy.