Ten leading US climate scientists spoke on Tuesday of the need for more urgent action to tackle global warming.

They warned that climate models might have grossly underestimated the rises in temperature that will soon occur.

The team called for a major shift to cleaner fuel technologies to constrain the rapid growth in greenhouse gases.

"We're in the middle of a large, uncontrolled experiment on the only planet we have," said Don Kennedy, the editor-in-chief of Science magazine.

"Global warming has taken place and at our present rate of doing business, there is going to be a lot more of it and it will have serious consequences," added the co-organiser of the open gathering of researchers in Washington DC.