The U.N.’s Intergovernmental Panel on Climate Change (IPCC) has released a summary of its latest report. This has had the intended effect: generating fresh gloom-and-doom headlines about global warming. “A grim and powerful assessment of the future of the planet,” said the New York Times, a representative example. The chairman of the IPCC, Rajendra Pachauri, said, “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. Moreover, what is new represents a pullback from the gloomier claims of 2001. Notwithstanding the authors’ bold assertion of 95-percent confidence that human activity influences global warming, it appears from this short summary of the full 1,400-page report — which, inexplicably, the IPCC won’t release until May — that there has been only slight progress over the past five years in refining our climate models and resolving key uncertainties acknowledged in the last report.
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 these 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 purporting to show that the planet is warmer today than at any time in the last thousand years, a demonstration which required erasing the inconvenient medieval warm period and the little ice age. The new IPCC report has also reduced its estimate of the human influence on warming by one-third (though this change was not flagged for the media, so few if any news accounts took notice of it). That reduction is one reason the IPCC narrowed the range of predicted future warming, and lowered the new midpoint — i.e., the most likely prediction of temperature increase — by a half degree, from 3.5 degrees Celsius in 2001 to 3 degrees in this report. The new assessment also cuts in half the range of predicted sea-level rise over the next century. Now the maximum prediction is about 17 inches, as compared with the 20 to 30 feet Al Gore dramatizes in his horror film. (Which truths are inconvenient now?) There are murmurs from the green warriors that the new report is a disappointment, and no wonder.
Keep in mind that this summary covers only one of the three IPCC working groups that will report their findings later this year. Good news for insomniacs: The three complete reports, covering science, impacts, and mitigation, will run to nearly 5,000 pages. It’s troubling that, in what seems a clear attempt to spin the media, the IPCC has released only one summary in advance of the complete reports.
Climate change is real — the world is warming modestly, and this fact should be taken seriously. But the continuing panic of Gore & Co. in the face of growing evidence that previous predictions were exaggerated and politicized should bolster the position of those who advocate sensible climate policy. Such policy would emphasize development of new energy technologies, and eschew the starvation diet of the Kyoto Protocol.