John Houghton, a former key member of the Intergovernmental Panel on Climate Change, said the impacts of global warming are such that "I have no hesitation in describing it as a weapon of mass destruction."

He said the United States, in an "epic" abandonment of leadership, was largely responsible for the threat.

"Like terrorism, this weapon knows no boundaries," Houghton said. "It can strike anywhere, in any form -- a heatwave in one place, a drought or a flood or a storm surge in another"

The US mainland was struck by 562 tornados in May, killing 41 people, he said, but the developing world was hit even harder.

For example, pre-monsoon temperatures this year in India reached a blistering 49C (120F), 5C (9F) above normal.

"Once this killer heatwave began to abate, 1,500 people lay dead -- half the number killed outright in the September 11 attacks on the World Trade Centre," Houghton said.

He said British Prime Minister Tony Blair begun to face up to this, rhetorically at least, but "nowadays everyone knows that the US is the world's biggest polluter, and that with only one 20th of the world's population it produces a quarter of its greenhouse gas emissions."

"But the US government, in an abdication of leadership of epic proportions, is refusing to take the problem seriously -- and Britain, presumably because Blair wishes not to offend George Bush -- is beginning to fall behind too," Houghton said.

Apart from being co-chairman of the scientific assessment group of the climate change panel, Houghton is also the former chief executive of the British Meteorological Office.

TERRA.WIRE