In case you don’t already know what’s in it you can download the IPPC AR4 report from here. You should know what’s in it, because the summary for policy makers was released early this year in a “cart before the horse” exercise.
I can’t help thinking that the IPCC reports are the biggest exercise in collective confirmation bias since the invention of religion. Now I’m on the record as being religious, and also believing that CO2 contributes to warming of the globe, so please don’t send me any mail saying that I’m a “denier”. But I do believe that we should test everything, and only hold fast to that which is true. And on that basis the IPCC reports fall far short of the standards set by the empirical enlightenment tradition of which I’m also a disciple.
The IPCC reports seem to me to grab onto any bit of evidence that supports their thesis – that global warming will be catastrophic – while ignoring any contrary evidence. This then extends to categorising any meteorological occurence that is relatively rare as being a product of global warming. Worst drought in Australia in 100 years – must be global warming.
This is very similar to the primitive religious view of the world in that not only is confirmation bias at work, but it centralises the world around mankind. So for example if the moon disappears in an eclipse, for a primitive it must be our fault, and we need to make some sacrifice to change it. A more sophisticated scientific and religious view of the world disentangles cause and effect. Maybe god caused the eclipse, but if he did, it is as a consequence of the way he created the universe, not of anything we ourselves have done, and I say “maybe” because you can take the concept of god out of this altogether, and it still holds as a logical proposition.
So, scientists start to act more like priests than scientists. For example, the report says that it is 90% likely that the scenarios outlined in it will come to occur. This is not a statistical statement, or even a core promise. This is the equivalent of saying that interest rates will always be lower under the Liberals, or that God exists. In fact, I’d give you better odds on the first than the second, but in each case less than 90 percent, but this will just be a personal opinion, not a scientific one, because there is no way to statistically calculate the probability. To do that you have to have an event which recurs.
To be scientific you also need to be able to construct an experiment to test your theory, but in the case of climate change you can’t verify the results until after the event, and even then, in the case of climate change, even if it did get very much warmer, disentangling cause from effect would probably still be impossible. So my odds would be an expression of a personal, not a scientific, view.
Which is one of the problems that I have with the IPCC. The scientists writing the report should be as aware as I am of the limits of “probability” in this sort of exercise, so why do they attempt to pass faith off as science?