By all measures of global temperature — and we have three — Hansen’s forecast was a bust. Temperatures on the ground rose a mere 0.11º C during the decade, while temperatures of the lower atmosphere measured by satellites and weather balloons actually declined — by 0.24º C and 0.36º C, respectively.
In a recent paper in the Proceedings of the National Academy of Sciences, Hansen explains why he was wrong: the planet is getting greener and consuming carbon dioxide, the main greenhouse warming gas, at a rate far exceeding what he and the other climate modelers predicted a mere 10 years ago. In fact, the observed changes in carbon dioxide levels are below the lowest scenarios thought to be reasonable by none other than the United Nations Intergovernmental Panel on Climate Change — otherwise known as the “consensus of 2,500 scientists” that Vice President Gore is fond of marshaling in support of his position on the issue.
We could have saved a lot of time and grief if we had just listened to the “cynics” (Washingtonese for those who don’t think Washington is required for global salvation) when Hansen made his 1988 splash. They pointed out that the observed planetary warming, even back then, was far too small to support Hansen’s forecast. And, to make things worse, at least half of that warming had occurred prior to 1930, before greenhouse changes could have caused it. The lion’s share of the warming was also confined to the coldest air masses of Siberia and northwestern North America in the dead of winter, where warming from an average temperature of -40 degrees Celsius to, say, -38 degrees, is hardly a disaster.
The failing paradigm of dramatic warming was to be shored up with a great deal of intellectual effort — as is common in science. Thomas Kuhn frequently pointed out in his many studies of the evolution of scientific thought that explanations become increasingly ornate and bizarre as the disconnection between models and reality broadens.