Reuters.com | Ocean, Arctic Studies Show Global Warming Is Real

"'The debate over whether or not there is a global warming signal is now over, at least for rational people,' he said.

The report was published one day after the United Nations Kyoto Protocol took effect, a 141-nation environmental pact the United States government has spurned for several reasons, including stated doubts about whether global warming is occurring and is caused by people.

Barnett urged U.S. officials to reconsider.

'Could a climate system simply do this on its own? The answer is clearly no,' Barnett said.

But then no one has accused the Bush administration of being rational.