At most, the draft report says, climate change may have played a role in the disappearance of a few amphibians, fresh water fish and mollusks. Yet even the icons of catastrophic global warming, the polar bears, are doing surprisingly well. Their population has remained stable despite the shrinking of the Arctic ice cap.

Ragnar Kinzelbach, a zoologist at the University of Rostock, says essential data is missing for most other life forms, making it virtually impossible to forecast the potential effects of climate change. Given the myriad other human encroachments in the natural environment, Kinzelbach says, “crocodile tears over an animal kingdom threatened by climate change are less than convincing.”

The draft report includes a surprising admission by the IPCC — that it doubts its own computer simulations for species extinctions. “There is very little confidence that models currently predict extinction risk accurately,” the report notes. Very low extinction rates despite considerable climate variability during past hundreds of thousands of years have led to concern that “forecasts for very high extinction rates due entirely to climate change may be overestimated.”