Scientists walk out in protest at China's intransigence

Some of the world's best-informed climate change scientists walked out of an all-night drafting session of yesterday's report on global warming, as tempers flared.

The protest, which included a prominent US scientist, took place after Chinese diplomats sought to water down a section spelling out the degree of certainty researchers attach to the impact of climate change.

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During a fractious night of negotiation, China and Saudi Arabia were identified as the countries which sought most systematically to dilute the text.

Feelings were running high because the summary produced will be read by heads of government, including Tony Blair and Germany's Angela Merkel, according to Hans Verolme, director of WWF's climate change programme. The summary is an unusual hybrid, crafted by scientists but endorsed by diplomats, thereby gaining political, as well as academic, credibility.

One of those who left the large, crescent-shaped conference room in the Charlemagne building in Brussels was Cynthia Rosenzweig, senior research scientist at the Nasa Goddard Institute for Space Studies and one of the report's authors.

Asked why things got so heated, she replied: "I think that scientists and government representatives are two different groups of people, they have different ways of operating and standards of evidence. When scientists come together with these government people you have some sparks flying." She added: "The lead authors wanted the governments to know that we felt strongly that we have very high confidence that the statement was justified. So I made that point emphatically".

The US eventually brokered a compromise which avoided any watering down of the reference to a "very high confidence" by removing the clause altogether.

Among the delegates there had been a clear spread of views. One observer blamed China and Saudi Arabia for seeking to water down the text, Russia for being "idiosyncratic" and the US for being "difficult in a nuanced way". Russia's representative, Oleg Anisimov, for example, said there were ways in which "climate change could be not so bad for Russia because it could lead to warmer temperatures and less money would have to be spent on heating." In addition, Russia's crop yields would rise.

Mr Verolme warned that politics could undermine climate change research "if you have governments questioning the level of scientific confidence or saying 'this is not globally observed' whereas the underlying document says this is a global phenomenon observed by scientists."

He added that he was "disappointed that there are countries which feel the need to reduce the political pressure and they do it through this process".

Mr Verolme predicts that, when the Intergovernmental Panel on Climate Change meets next month in Bangkok to discuss the economic fallout of climate change, "it will be worse".

"You can bet that that text will be really scrutinised," he said. "I am looking forward to some sleepless nights in Bangkok".