Planet Gore.(PUBLIC POLICY)(Al Gore)

THE U.N.'s Intergovernmental Panel on Climate Change (IPCC) has released a summary of its latest report. The release has had the intended effect: generating fresh gloom and doom about global warming. The New York Times described the report as "a grim and powerful assessment of the future of the planet." Meteorologists who dissent from the "consensus" on warming are already being ostracized. And the chairman of the IPCC, Rajendra Pachauri, has said, quite forthrightly, "I hope this report will shock people."

The shock, however, is that the latest summary contains very little that was not in the IPCC's last report, in 2001. What is new, moreover, is a retreat from earlier, gloomier claims. Notwithstanding the authors' bold assertion of 90 percent confidence that human activity causes warming, it appears from the short summary of the full report that there has been only slight progress over the past five years in refining our climate models and resolving key uncertainties.

The 2001 report identified twelve factors in climate "forcings" (i.e., factors such as greenhouse-gas emissions, clouds, and solar radiation that "force" temperatures higher or lower). These twelve factors went into the computer models to generate predictions about future warming, but the IPCC said in 2001 that the level of scientific understanding for seven of the twelve factors was "very low." Most of the seven are significant "negative forcings" that cool the planet, and may be underestimated in climate models. The new report has consolidated the twelve factors into just nine; yet the IPCC still says our level of understanding is "low" or "medium-low" for six of the nine.

Gone from the latest summary is the infamous "hockey stick" of the 2001 report. This was a graphic ...