I was unpleasantly annoyed by a Clive James item on the radio yesterday, which you can read in full. I enjoyed the discussion of the golf ball crisp, but then he moves on to scepticism about man’s responsibility for climate change, suggesting that because there are scientists challenging the consensus, the “science isn’t settled”. Later he says “if you have a division on that scale, you can’t call it a consensus”. What does he mean by scale? Has he surveyed all the available literature and scientific opinion? He bridles about being called denialist, but he is using the exact same argument as the AIDS denalists in suggesting that there is an even balance between the Yays and the Nays. This displays a complete misunderstanding of how science should and does work.
As I see it, all scientific theories are based on the best possible combination of explaining existing observations and predicting future ones. This “best possible” could well be completely wrong: Newtonian relativity worked to get us so far into the air, we needed Einsteinian relativity to get space travel underway, and we are certain that there is a new theory needed to really understand what’s going on out there. So there must, repeat must, be scientists challenging the status quo. It’s how science works.
Consensus in science does not appear like a jury unanimous on a basis beyond reasonable doubt; rather the majority position must regularly assess and state its position and respond to challenge. On this basis, it is clear that the consensus is in: the earth is warming, it will cause us problems and we are responsible. Yes, we could be proven wrong on all these (e.g. ten years ago you would have been laughed out of the lab for suggesting that a bacterium caused stomach ulcers, but we now know that H. Pylori does), but that is not where the IPCC is sitting (and it has done the job of canvassing and weighing all available opinions).
We absolutely do not know that the sun will rise again tomorrow. We are really pretty sure that it will, though, so we will take action based on that pretty strong belief. We’re in the same position with climate change: we need to take some action, and fast.