Climate action scepticism takes at least three forms:
those that deny that there is the possibility (they deny that it is feasible for humanity to coordinate sufficiently to prevent or reverse whatever human-controllable element there is to climate change) those that deny it is worth doing (they believe that, even if there is human-induced climate change and even if it could be prevented or reversed, the costs of doing so would be greater than the benefits)
The three forms are independent in the sense that one need not hold any one of them in order to hold the others.
There is adequate science for us to set aside form (1) scepticism for the moment. I do not suggest that the scientific debate is "over" - no scientific debate ever ends - but we certainly have strong enough scientific evidence for the policy debate to need to take account of it.
Unfortunately, however (I suggest) form (1) scepticism does not get set aside nearly often enough. What happens, instead, is that anyone trying to offer either form (2) or particularly form (3) scepticism is shouted down - on the one side by form (1) sceptics who say the forms (2) and (3) sceptics are ignorant of this, this, and this; and on the other by climate change action advocates who allege that form (3) scepticism is just form (1) scepticism dressed up or that there cannot be any form (3) scepticism without being a form (1) sceptic or that just start talking about why form (1) scepticism is wrong or irrelevant. The consequence is that the serious form (3) debate never occurs.
Let's first see why it is wrong to say that one cannot be a form (3) sceptic without being a form (1) sceptic. For example, they say "Would there be any non-trivial cost-benefit analysis if a dinosour-killing asteroid were headed towards the earth?" They are quite wrong in this, for three important reasons. Firstly, because no serious model suggests that climate change is remotely as dangerous as a dinosaur-killing asteroid. Second, because the overwhelming bulk of alleged costs of climate change arise in a century to several centuries' time, and even in the case of a dinosaur-killing asteroid that was going to arrive in a couple of centuries' time there might be questions such as "Are we better to try to prevent the asteroid from striking the earth or would it be cheaper and more likely to work if we adapted by evacuating the earth to Mars?" Third, because it would be an open question whether it were better if we bore the costs of developing the anti-asteroid technologies today or whether they would be better borne tomorrow or in ten or fifty years' time by people richer and more advanced than we would be.
That point is easily dealt with. What seems to be less easy, unfortunately, is the addiction form (1) sceptics and climate change action advocates have to debating only with each other. On this morning's Today programme, Professor Diana Liverman was asked whether there was any sense at the Copenhagen conference of the feeling some people have that it might not be worth the costs of acting. i.e. she was asked a form (3) sceptic's question. She responded by saying that there was great confidence in the science and that only delegations such as the Saudi Arabian had attempted to raise any scepticism about the science. The presenter should have pressed her to answer his question, not another one, except that of course she had answered his question - obviously, there is so little comprehension of form (3) scepticism that it was having no impact whatever on the Copenhagen discussions.
Those of you that are form (1) sceptics need to get hold of the following point: you have lost the scientific argument within the policy community, at least for now. If you want to get anywhere in opposing action (action that you must believe is pointless and hence for which the costs outweigh the benefits), you need to move on to the cost-benefit argument and let those of us that are form (3) sceptics make the case without being continuously undermined by form (1) carping from the background. The policy community has engaged with form (1) scepticism and found it wanting. The policy community is, at present, simply failing to engage or debate with form (3) scepticism at all.
