As you all know I'm perfectly willing to go along with the idea that climate change is indeed a problem that we are doing something about and that that something should be a carbon tax. All of this being based on the dual points that I know nothing about the science of all of this but a great deal about the economics. So, if the scientists tell me that it's happening then OK, here's what we should do about it.

And it's worth noting that this makes me entirely mainstream: think of that, a subject where Worstall is in fact entirely mainstream. It's what the Stern Review says for example.

However, the next IPCC report may well end up with my changing my views on this. Here's a taster from a recently leaked version:

Containing the concentration to 480 ppm “would entail global consumption losses” of 1 percent to 4 percent in 2030. That range would rise to 2 percent to 6 percent in 2050 and then to as much as 12 percent in 2100 when compared with scenarios that don’t involve fighting climate change, according to the document.

The only argument in favour of doing something about climate change is that not doing something will be even more expensive than doing something. And the calculation was, from the Stern Review, that we should be willing to spend 1-2% of global GDP each year in order to avoid a near catastrophic 20% decline in it when the changes occur. But it's important to note that that 20% decline is only a possibility, even Stern didn't say it was a certainty.

But now we've got the IPCC apparently saying that we're going to be losing 12% of GDP globally in order to avert the possibility of a 20% decline. That's not a cost benefit analysis that makes sense.

Which leads us to a quite delightful possibility. That the next IPCC report on hte dangers of climate change is actually going to end up proving that we shouldn't do anything about climate change. For the doing things will be more expensive than the damages we suffer from not doing anything.

Probably, given that that 20% decline in GDP is indeed only a possible event, not a certain one.

And yes, I am aware that that picture of the polar bear is not one drowning because of the melting ice.