Tuesday, January 28, 2014

Every time I hear about the consensus of climate scientists, I read a climate scientists saying something like this:


All of the above is background to one of the great mysteries of the climate change issue. Virtually all the scientists directly involved in climate prediction are aware of the enormous problems and uncertainties still associated with their product. How then is it that those of them involved in the latest report of the Intergovernmental Panel on Climate Change (IPCC) can put their hands on their hearts and maintain there is a 95 per cent probability that human emissions of carbon dioxide have caused most of the global warming that has occurred over the last several decades?

Bear in mind that the representation of clouds in climate models (and of water vapour, which is intimately involved with cloud formation) is such as to amplify the forecast warming from increasing atmospheric carbon dioxide—on average over most of the models—by a factor of about three. In other words, two-thirds of the forecast rise in temperature derives from this particular model characteristic. Despite what the models are telling us—and perhaps because it is models that are telling us—no scientist close to the problem and in his right mind, when asked the specific question, would say that he is 95 per cent sure that the effect of clouds is to amplify rather than to reduce the warming effect of increasing carbon dioxide. If he is not sure that clouds amplify global warming, he cannot be sure that most of the global warming is a result of increasing carbon dioxide.

Bear in mind too that no scientist close to the problem and in his right mind, when asked the specific question, would say there is only a very small possibility (that is, less than 5 per cent) that internal ocean behaviour could be a major cause of the warming over the past half-century. He would be particularly careful not to make such a statement now that there has been no significant warming over the most recent fifteen or so years. In the mad scurry to find reasons for the pause, and to find reasons for an obvious failure of the models to simulate the pause, suddenly we are hearing that perhaps the heat of global warming is being “hidden” in the deep ocean. In other words we are being told that some internal oceanic fluctuation may have reduced the upward trend in global temperature. It is therefore more than a little strange that we are not hearing from the IPCC (or at any rate not hearing very loudly) that some natural internal fluctuation of the system may have given rise to most of the earlier upward trend.

In the light of all this, we have at least to consider the possibility that the scientific establishment behind the global warming issue has been drawn into the trap of seriously overstating the climate problem—or, what is much the same thing, of seriously understating the uncertainties associated with the climate problem—in its effort to promote the cause. It is a particularly nasty trap in the context of science, because it risks destroying, perhaps for centuries to come, the unique and hard-won reputation for honesty which is the basis of society’s respect for scientific endeavour. Trading reputational capital for short-term political gain isn’t the most sensible way of going about things.

The trap was set in the late 1970s or thereabouts when the environmental movement first realised that doing something about global warming would play to quite a number of its social agendas. At much the same time, it became accepted wisdom around the corridors of power that government-funded scientists (that is, most scientists) should be required to obtain a goodly fraction of their funds and salaries from external sources—external anyway to their own particular organisation.//

Garth Paltridge is an emeritus professor at the University of Tasmania and a fellow of the Australian Academy of Science. He is the author of The Climate Caper: Facts and Fallacies of Global Warming. He was a chief research scientist with the CSIRO Division of Atmospheric Research.



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