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Politics : Foreign Affairs Discussion Group -- Ignore unavailable to you. Want to Upgrade?

To: c.hinton who wrote (250234)	12/1/2007 4:30:36 PM
From: Nadine Carroll	Read Replies (1) \| Respond to of 281500

ch, the earth gets warmer and cooler all the time. Climate is a chaotic system. The feedback loops between warmer temps, cloud formation and precipitation are not understood well enough to be properly modeled by these climate models that the IPCC touts as the end-all and be-all of knowledge; they are stuck in with paramaters on cells that get fudged to make the numbers come out right. I can't say that climate change isn't happening as the models say, but anyone who tells you that the case is proved and we know exactly how much of the warming is due to manmade carbon emissions is talking propaganda, not science. The physicist Freeman Dyson understands from experience the hazards of over-reliance on elegant models: The "fluff," Prof. Dyson explains, comes from climate-change models that predict all manner of catastrophe. The models count for naught as predictive tools. "I have studied their climate models and know what they can do," Prof. Dyson says. "The models solve the equations of fluid dynamics and do a very good job of describing the fluid motions of the atmosphere and the oceans. They do a very poor job of describing the clouds, the dust, the chemistry and the biology of fields, farms and forests. They do not begin to describe the real world that we live in." Prof. Dyson explains that the many components of climate models are divorced from first principles and are "parameterized" -- incorporated by reference to their measured effects. "They are full of fudge factors that are fitted to the existing climate, so the models more or less agree with the observed data. But there is no reason to believe that the same fudge factors would give the right behaviour in a world with different chemistry, for example in a world with increased CO2 in the atmosphere," he states. Prof. Dyson learned about the pitfalls of modelling early in his career, in 1953, and from good authority: physicist Enrico Fermi, who had built the first nuclear reactor in 1942. The young Prof. Dyson and his team of graduate students and post-docs had proudly developed what seemed like a remarkably reliable model of subatomic behaviour that corresponded with Fermi's actual measurements. To Prof. Dyson's dismay, Fermi quickly dismissed his model. "In desperation, I asked Fermi whether he was not impressed by the agreement between our calculated numbers and his measured numbers. He replied, 'How many arbitrary parameters did you use for your calculations?' I thought for a moment about our cut-off procedures and said, 'Four.' He said, 'I remember my friend Johnny von Neumann [the co-creator of game theory] used to say, with four parameters I can fit an elephant, and with five I can make him wiggle his trunk.' With that, the conversation was over." Prof. Dyson soon abandoned this line of inquiry. Only years later, after Fermi's death, did new developments in science confirm that the impressive agreement between Prof. Dyson's model and Fermi's measurements was bogus, and that Prof. Dyson and his students had been spared years of grief by Fermi's wise dismissal of his speculative model. Although it seemed elegant, it was no foundation upon which to base sound science. nationalpost.com