Bad news: Andrew Sullivan quotes Jim Manzi quoting IPCC:
This is the crux of the problem with McKibben’s argument: According to the IPCC, the expected economic costs of global warming are about 3 percent of GDP more than 100 years from now. This is pretty far from the rhetoric of global devastation that McKibben, and so many others, use.The question raised obviously is the authority of this claim. Did the IPCC make such a claim? In what context? (Manzi does not provide a reference.) Is there any basis for this claim? What is the confidence interval?
For myself, I have always thought of WG I as authoritative, and WG II and WG III as speculative. Much of the damage to the reputation of climate science has emerged from attributing WG II speculation to "climate science".
I will probably change everything I'm doing in my professional life if anyone can convince me that the 3% prediction is reliable. I think there's very little chance of that, but Manzi is right on this point: "One of the great strengths of TNR, in my opinion as an outsider, is that it has made a habit of facing up the strongest arguments of its ideological opponents." Well, I stopped following TNR fifteen years ago on the grounds of its exasperating blindness on middle east policy and a divergence of interest in general, but I support the principle. So, is there really some way to limit the damage to an unmeasurably small modest reduction of growth?
I have to say my BS detectors are pegged on this one. It will be interesting if blame for this really attaches to IPCC.
Amusingly, Sullivan takes the bait:
But since when did conservatives only care about "economic costs"? I respect Manzi's cost-benefit argument, and his policy pragmatism. But there is a moral dimension to real conservatism, even a spiritual one, that does not treat the planet as something to be used, but as something to be a sensible steward of.Maybe so. But if we really believe that "growth" remains possible for a century, it necessarily follows that the probability of real environmental crisis is small. This is not despite, but because of, the fact that the economy is part of the environment.
In future, only actual consensus positions should be reported as such by IPCC, please and thanks. Any clues where Manzi got his idea and what we can do about it?
That all said, I like Sullivan's concluding paragraphs:
Confirming that the present day Republican party is not conservative.
The earth is something none of us can own or control. It is something far older than our limited minds can even imagine. Our task is therefore a modest one: of stewardship, the quintessential conservative occupation.
Conservatives do not seek to remake the world anew. We do not hope to impose upon it some abstract ideological “truth” or bring about some new age for humanity. We seek as conservatives merely to live up to our generational responsibility and to care for the inheritance we have in turn been given. This ecological vision is a Burkean one, which is why Toryism’s natural colour is as much green as blue.
Update: Plenty of sensible caveats (see comments) notwithstanding, I'd be enormously relieved to see that we are talking about a cost of 3% per century. This works out to a hair less than 0.03% per year.
This year's cost would be 18.3 billion dollars at that rate. Since costs are expected to accelerate, we can refute the estimate if we can find 18 billion in losses this year.
Estimates from the Pakistan flood losses alone range from 9 billion to 43 billion.
Can we put this down to climate change? I think history will do so. But for present purposes it doesn't matter. All we need to do is find excess weather/hydrosphere/cryosphere related costs. and Pakistan surely qualifies. This means that we are already bearing the brunt of business-as-usual climate change.
That is, if the estimate is correct, this year would be worse than average in terms of climate related costs averaged over the next century. I think that implies changes much smaller than the WG I consensus, which expects accelerating change. Therefore it would appear to be inconsistent with the rest of IPCC.
Note also that in comments Brian Schmidt points out that this appears in AR4 only as a quotation from AR3 upon which some doubt is subsequently cast.
In any case the idea that a problem like climate change separates out linearly from other problems itself seems highly dubious. I retain my opinion that Manzi's reasoning is based on a very flimsy premise.