IPCC exaggerates risks: Opposing view

• Due to its charter and sheer bureaucratic momentum%2C the IPCC is compelled to claim it is more confident than ever.
• Policymakers and the public have no reason to believe this discredited oracle.
• It%27s time to start listening to other voices in the debate%2C such as the Nongovernmental International Panel on Climate Change.

Environmentalists hoped the latest study from the United Nations' Intergovernmental Panel on Climate Change (IPCC) would finally end the increasingly acrimonious debate over the causes and consequences of climate change. It has had the opposite effect.

MIT physicist Richard Lindzen called the IPCC report "hilarious incoherence." British historian Rupert Darwall labeled it "nonsense" and "the manipulation of science for political ends." Judith Curry of the Georgia Institute of Technology says the IPCC suffers from "paradigm paralysis" and should be "put down."

The most precise criticism of the IPCC's report came from the editors of Nature, one of the world's most distinguished science journals: "Scientists cannot say with any certainty what rate of warming might be expected, or what effects humanity might want to prepare for, hedge against or avoid at all costs."

Despite decades of research funded by taxpayers to the tune of billions of dollars, we are no more certain about the impact of man-made greenhouse gases than we were in 1990, or even in 1979 when the National Academy of Sciences estimated the effect of a doubling of carbon dioxide to be "near 3 degrees C with a probable error of plus or minus 1.5 degrees C."

The lower end of that range, which is where the best research on the likely sensitivity of climate to carbon dioxide lands, is well within the bounds of natural variability.

Significantly, the IPCC has backed down from its previous forecasts of increases in droughts and hurricanes. And it admits, but does not explain, why no warming has occurred for the past 15 years.

Due to its charter and sheer bureaucratic momentum, the IPCC is compelled to claim it is more confident than ever in its alarmist predictions, even as real-world evidence falsifies them at every turn. Policymakers and the public have no reason to believe this discredited oracle.

It's time to start listening to other voices in the debate, such as the 50-some scientists who make up the Nongovernmental International Panel on Climate Change (NIPCC).

According to its latest report, "the IPCC has exaggerated the amount of warming likely to occur if the concentration of atmospheric carbon dioxide were to double, and such warming as occurs is likely to be modest and cause no net harm to the global environment or to human well-being."

Joseph L. Bast is president of The Heartland Institute, a Chicago-based research organization that advocates free-market policies.