Valencia, Spain: Delegates from more than 140 countries agreed Friday on an environmental "instant guide" for policy makers, stating more forcefully than ever that climate change had begun and that it threatened to alter the planet irreversibly.

The document summarizes the scientific consensus on human-induced climate change. It will be distributed to delegates at a crucial meeting in Indonesia next month that is intended to begin a political process on international cooperation to control global warming.

Comment: It is the government and media consensus rather than scientific consensus. The scientific community is far from reaching a consensus on this.

Five days of sometimes tense negotiations ended before dawn with the approval of a 20-page summary of thousands of pages of data and computer projections compiled over six years by the Intergovernmental Panel on Climate Change, which was awarded the Nobel Peace Prize this year with Al Gore.

The work describes how climate systems are changing and why, the effects they are having on mankind and ecosystems and various scenarios of future impacts, depending on how quickly action is taken to slow the trend.

The summary and a longer "synthesis report" of about 70 pages were expected to be formally adopted after proofreading. They will be released Saturday at a news conference attended by the United Nations secretary general, Ban Ki Moon.

"Warming of the climate system is unequivocal," the summary begins, a statement that participants in the meeting said was meant to dispel any skepticism about the reality of climate change.

In a startling and much-debated conclusion, the document warns that human activity risks causing "abrupt or irreversible changes" on Earth, including the widespread extinction of species and a dramatic rise in sea levels before the end of this century.

Comment: At least it is admitted that this conclusion is much-debated.

"I think overall it is a good and balanced document," said Bert Metz, an eminent Dutch scientist and one of the 40 authors of the draft. "In the end, a lot of people had to compromise."

Although it contains no previously unpublished material, the summary pulls together the central elements of three lengthy reports the climate panel released this year. "I think this will be the scientific imperative" propelling action, said Stephanie Tunmore of the Greenpeace environmental group, an observer at the talks.