?I don?t want to pick on Al Gore,? Don J. Easterbrook, an emeritus professor of geology at Western Washington University, told hundreds of experts at the annual meeting of the Geological Society of America. ?But there are a lot of inaccuracies in the statements we are seeing, and we have to temper that with real data.?

...Although Mr. Gore is not a scientist, he does rely heavily on the authority of science in ?An Inconvenient Truth,? which is why scientists are sensitive to its details and claims.

Criticisms of Mr. Gore have come not only from conservative groups and prominent skeptics of catastrophic warming, but also from rank-and-file scientists like Dr. Easterbook, who told his peers that he had no political ax to grind. A few see natural variation as more central to global warming than heat-trapping gases. Many appear to occupy a middle ground in the climate debate, seeing human activity as a serious threat but challenging what they call the extremism of both skeptics and zealots.

Kevin Vranes, a climatologist at the Center for Science and Technology Policy Research at the University of Colorado, said he sensed a growing backlash against exaggeration. While praising Mr. Gore for ?getting the message out,? Dr. Vranes questioned whether his presentations were ?overselling our certainty about knowing the future.?