No one is asking for radical changes, but if we don't stop pretending that what we do doesn't matter, they might be forced upon us (or our children).
PARIS (AP) - The world's leading climate scientists said global warming has begun, is "very likely" caused by man, and will be unstoppable for centuries, according to a report obtained Friday by The Associated Press.
The scientists - using their strongest language yet on the issue - said now that world has begun to warm, hotter temperatures and rises in sea level "would continue for centuries" no matter how much humans control their pollution. The report also linked the warming to the recent increase in stronger hurricanes.
"The observed widespread warming of the atmosphere and ocean, together with ice-mass loss, support the conclusion that it is extremely unlikely that global climate change of the past 50 years can be explained without external forcing, and very likely that is not due to known natural causes alone," said the report by the Intergovernmental Panel on Climate Change - a group of hundreds of scientists and representatives of 113 governments.
The phrase "very likely" translates to a more than 90 percent certainty that global warming is caused by man's burning of fossil fuels. That was the strongest conclusion to date, making it nearly impossible to say natural forces are to blame.
What that means in simple language is "we have this nailed," said top U.S. climate scientist Jerry Mahlman, who originated the percentage system. The 20-page report, which was due to be officially released later in the day, represents the most authoritative science on global warming.
On sea levels, the report projects rises of 7-23 inches by the end of the century. An additional 3.9-7.8 inches are possible if recent, surprising melting of polar ice sheets continues. But there is some cold comfort. Some, but not all, of the projected temperature and sea level rises are slightly lower than projected in a previous report in 2001. That is mostly due to use of more likely scenarios and would still result in dramatic effects across the globe, scientists said. Many scientists had warned that this estimate was too cautious and said sea level rise could be closer to 3-5 feet because of ice sheet melt.
Nevertheless, scientists agreed the report is strong.
"There's no question that the powerful language is intimately linked to the more powerful science," said one of the study's many co-authors, Andrew Weaver of the University of Victoria, who spoke by phone from Canada. He said the report was based on science that is rock-solid, peer-reviewed, and consensus.
"It's very conservative. Scientists by their nature are skeptics." The scientists wrote the report based on years of peer-reviewed research and government officials edited it with an eye toward the required unanimous approval by world governments. In the end, there was little debate on the strength of the wording about the role of man in global warming.
The panel quickly agreed Thursday on two of the most contentious issues: attributing global warming to man-made burning of fossil fuels and connecting it to a recent increase in stronger hurricanes. Negotiations over a third and more difficult issue - how much the sea level is predicted to rise by 2100 - went into the night Thursday with a deadline approaching for the report.
While critics call the panel overly alarmist, it is by nature relatively cautious because it relies on hundreds of scientists, including skeptics. "I hope that policymakers will be quite convinced by this message," said Riibeta Abeta, a delegate whose island nation Kiribati is threatened by rising seas. "The purpose is to get them moving."
The Chinese delegation was resistant to strong wording on global warming, said Barbados delegate Leonard Fields and others. China has increasingly turned to fossil fuels for its huge and growing energy needs. The U.S. government delegation was not one of the more vocal groups in the debate over whether warming is man-made, said officials from other countries. And several attendees credited the head of the panel session, Susan Solomon, a top U.S. government climate scientist, with pushing through the agreement so quickly.
The Bush administration acknowledges that global warming is man-made and a problem that must be dealt with, Bush science adviser John Marburger has said. However, Bush continues to reject mandatory limits on so-called "greenhouse" gases.