Over the years, the IPCC has behaved like a treed cat. Instead of closing its eyes and scurrying to the ground, it climbs onto even higher and thinner branches, while yowling ever louder. How does it back down from a quarter-century of predicting a quarter of a degree (Celsius) of warming every decade, when there’s been none for 17 years now?
In fact, as I demonstrated in a recent presentation to the American Geophysical Union, the reigning suite of climate models has now officially failed, with the difference between them and reality now statistically significant at the 1-in-20 level.
Since the beginning of 2011, at least 16 separate experiments published by nearly 50 researchers show that the “sensitivity” of temperature to carbon dioxide that is characteristic of the IPCC’s climate models is simply too high. “Sensitivity” is the amount of temperature change expected for a nominal doubling of atmospheric carbon dioxide.
The new IPCC assessment calls sensitivity “the single most important measure of climate response” because changes in global mean surface temperature are what drive other changes, like sea-level rise. If you blow the sensitivity, you also blow every forecast of what is supposed to happen because of climate change.
Historians tell us scientists are reluctant to abandon their overarching worldviews. The New York Times’ Andrew Revkin wrote in February that there is even greater than normal reluctance to admit to a lower sensitivity “because the recent work is trending towards the published low sensitivity findings from a decade ago from climate scientists best known for their relationships with libertarian groups.” Call me nameless.
So the IPCC has three options:
1. Vote at week’s end to “not accept” the latest report and start over;
2. Note the recent findings and include a prominent disclaimer directing readers to substantially discount anything they say about the effects of future climate change; or
3. Do nothing and mislead the world. Again.
Bet on Door No. 3, with the corollary that whoever legislates or promulgates climate policies based upon the new report will be putting his political career in very serious jeopardy.
— Patrick J. Michaels is the director of the Center for the Study of Science at the Cato Institute.