Article: Science, belief and rational debate
Scientists often model systems to predict what effects might be expected if variables change in a certain way. In the absence of anything resembling evidence for the causative effect of global warming, computer modelling was enthusiastically embraced to project likely changes on the basis of the understanding of how climate worked. So far, so good, but the output from these models, rather than being seen as indications of what might happen if the hypothesis was right, have taken the place of experimental observation.
So, in a circular argument, the models which are based on a particular hypothesis (the greenhouse effect with positive feedback) are taken to "prove" the hypothesis because they reproduce the pattern of twentieth century temperature change. Similarly, the projections for future temperature rise (which, we should remember, cover a large range) are regularly quoted as what will happen if carbon dioxide emissions are not drastically cut back.
Large numbers of people have been sufficiently convinced by the arguments to take it as read that the greenhouse gas hypothesis is essentially correct and that disaster will occur unless radical cuts are made in emissions. They have moved beyond the stage of questioning to simply not listening to anyone who raises doubts. But, what is worse, they are putting their faith in a hypothesis unsupported by anything more than circumstantial evidence. Because no-one can do more than point to observations, no new evidence is going to be produced which – as in the story of peptic ulcers – will provide direct, irrefutable corroboration of an alternative theory.
Read it all here.