The Catastrophist

Elizabeth Kolbert has an article about the cap and trade legislation and Jim Hansen. It's behind a paywall, but the New Yorker is one of those things you should subscribe to ($50/yr) so don't expect sympathy. Particularly interesting is Kolbert's description of how Hansen moved from space science (modeling Venus) to Earth science. After the discovery that CFC were killing off the ozone layer Hansen

"realized that we had a planet that was changing before our eyes, and that's more interesting," Hansen told me. The topic attracted him for much the same reason that Venus's coulds had: there were new research questions to be answered. He decided to try to adapt a computer program that had been designed to forecast the weather to see if it could be used to look further into the future. What would happen to the earth if, for example, greenhouse gas levels were to double.

"He never worked on any topic thinking it might be any use for the world," Anniek told me. "He just wanted to figure out the scientific meaning of it."

When Hansen began his modeling work, there were good theoretical reasons for blieving that increasing CO2 levels would cause the world to warm, but little empirical evidence. Average global temperatures had risen in the nineteen thirties and forties; then they had declined in some regions, in the nineteen fifties and sixties. A few years into his project, Hansen concluded that a new pattern was about to emerge. In 1981, he became the director of GISS. In a paper published that year in Science, he forecast that the following decade would be unusually warm. (That turned out to be the case). In the same paper, he predicted that the nineteen nineties would be warmer still. (That also turned out to be true.) Finally he forecast that by the end of the twentieth century a global warming signal would emerge from the "noise" of natural climate variability. (This too proved to be correct.)

Later, Hansen became even more specific. In 1990, he bet a roomful of scientists that that year, or one of the following two, would be the warmest on record. (Within nine months, he had won the bet. ) In 1991, he predicted that, owing to the eruption of Mt. Pinatubo, in the Philippines, average global temperatures would drop, and then, a few years later, recommence their upward climb, which was precisely what happened.

From early on, the significance of Hansen's insights was recognized by the scientific community. "The work that he did in the seventies, eighties and nineties was absolutely groundbreaking," Spencer Weart, a physicist turned historian who has studies the efforts to understand climate change told me. He added, "It does help to be right."

"I have a whole folder in my drawer labelled 'Canonical Papers,' Michael Oppenheimer, a climate scientist at Princeton, said. "About half of them are Jim's"

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