The UN's Intergovernmental Panel on Climate Change, at a news conference in Paris, will release part one of a four-volume survey, the first such report since 2001. The study was reviewed by more than 2,500 scientists from 130 countries.

The IPCC will revise forecasts for rises in temperatures and sea levels this century. The panel will say it is more than 90 percent likely that global warming is being caused by human activities, Philip Clapp, president of the U.S. National Environmental Trust, said Jan. 31 in Washington. The degree of certainty in the last report was 66 to 90 percent.

"This is a statement by the largest scientific panel ever put together on a major scientific issue that we now have the smoking gun on global warming,'' said Clapp, who has seen portions of the draft. "The central message to governments is that we are at the tipping point and between 2015 and 2025 we have to stabilize the world's emissions'' of greenhouse gases, and then reduce them.

Industrial Revolution

"The science of climate change, of global warming, is now unambiguous: the Earth is getting hotter, the weather is becoming more variable and this is due to our own industrial revolution,'' U.K. Environment Secretary David Miliband said in a Jan. 31 interview. "All the predictions are that the problem is becoming more urgent, that the scientists are becoming more certain and that the dangers are becoming more real.''

The IPCC's report issued today is entitled "Climate Change 2007: the Physical Science Basis.''

Scientists say that carbon dioxide (CO2) and other gases produced by burning fossil fuels cause the Earth to heat up when they linger in the atmosphere, trapping energy from the sun that would otherwise reflect back into space.

The level of greenhouse gases in the atmosphere is at its highest in at least 650,000 years, European scientists who analyzed ice cores from Antarctica said in the journal Science in November 2005.

The IPCC will narrow the bands for its forecast on temperature rise because of a "greater degree of certainty'' in the science, Steve Sawyer, Climate and Energy Policy Advisor for Greenpeace International, said in a Jan. 31 telephone interview.