A warming theory that has melted away

In defending his strategy for fighting climate change, Oliver Tickell abandons his entire argument

Björn Lomborg
guardian.co.uk,
Monday August 25 2008 19:00 BST

Oliver Tickell defends against my critique his visions of 4C leading to a catastrophic future. Two casual observations lend themselves readily. First, Tickell has entirely abstained from defending his claim for human extinction from 4C. Thanks. Second, I was clearly wrong when I said that Tickell's claim for 70-80 metres of sea level rise had maxed out campaigners' scare potential because that means all ice is melted. Showing an amazing ability to raise the stakes none the less, Tickell now talks about sea level going 100m higher.
The UN climate panel (IPCC) says that 4C will lead to a rise a hundredth of that figure; but Tickell simply claims such moderate projections are "dangerously misplaced". All I can see is that such facts are terribly inconvenient.
He summarily dismisses (as "outdated econometric models") the analysis of one of the IPCC lead climate economist authors, when the model points out that the damage will be quite modest at 3.5% of GDP. He assures us this "is not to dismiss economics as a whole" – because he can find two economists who support his argument, embracing Stern and Weitzman eagerly. It is hard not to see this as opportunistic cherry-picking: Stern might have been incomplete but his work "yielded many useful findings – not least that swift and decisive action to mitigate climate change is" the right way to go.
I will not deal with Stern here. Many others have pointed out that the Stern Report has seriously exaggerated the peer reviewed evidence and massaged the analysis to get his results (see, for example, Byatt et al, 2006; Carter, de Freitas, Goklany, Holland, & Lindzen, 2006; Dasgupta, 2006; Mendelsohn, 2007; Nordhaus, 2006e; R. S. J. Tol, 2006; R. S. J. Tol & Yohe, 2006; Varian, 2006; Yohe, 2006, see also my critique in my book Cool It). Weitzman, who Tickell likes when he agrees with him, actually criticises Stern: "As economic analysis the Stern Review dwells in a non_scientific state of limbo." Even then, Stern never did a proper cost-benefit analysis. Such analyses overwhelmingly show that strong early carbon cuts are a bad idea.
But it is interesting to assess Weitzman's argument (My arguments are partly indebted to Professor Nordhaus (pdf)). Tickell (and many other campaigners) fancies Weitzman, because his economic argument seems to support draconian climate policies. While very technical, it relies on a fairly straightforward gist. All risks you can think of – even catastrophic ones – have non-zero risk. Thus, it is possible (if not very likely) that global warming will not only increase the planet's temperature by 4C, but 10C. Heck, it might even increase beyond 20C – which Weitzman with armchair climatology, suggests might have a probability of 1%. Since evidence for or against such extremes is scarce, accumulating evidence can only slowly close us in on their true probability. Yet, for any given amount of evidence, there will always be sufficiently outrageous risks (think 30C) that are sufficiently unbound by evidence and sufficiently close to negative infinite utility that the total net utility is negative infinity. Thus, we should be willing to spend all our money to avoid it.
Now, in principle all economists would agree that non-trivial risks should be included in the model, and for example, Nordhaus has done that analytically in cost-benefit models (they still show that large emission cuts are not warranted). However, the Weitzman result curiously means that the more speculative and fuzzy the extreme event, the more it counts in the total utility.
This is an argument driven by a technicality – essentially a claim that we are willing to pay an infinite amount to avoid even an infinitesimal risk of annihilation. Yet we demonstratively aren't – and shouldn't be. Civilization-ending asteroids hit the earth once every 100m years, but at present we only spend $4m per year to track them. Maybe we should pay $1bn. But we shouldn't spend everything.
This underscores the fatal flaw in the Weitzman argument. When we allow all scary, fuzzy concerns onto centre stage, there is no end to where we should spend all our money. Every conceivable policy measure has a non-zero risk of catastrophe and so should be avoided at any cost. Biotechnology, http://www.wisegeek.com/what-is-a-strangelet.htm strangelets, runaway computer systems, nuclear proliferation, rogue weeds and bugs, pandemics, and asteroids are just a small sample of the areas each of which we should spend all our money on.
Tickell doesn't deal with these arguments at all. As with Stern, he simply picks Weitzman because the policy conclusion fits. Tickell then claims that spending $2tn annually on large-scale emissions cuts will provide the best insurance for mankind. But this ignores that investments in energy R&D will probably long-term cut 11 times more CO2. Moreover, if our goal is not just to cut CO2 but to help people and the planet, we can do even more good by focusing on simple solutions such as investing in nutrition, health and agricultural technologies. Instead of avoiding a couple of thousand extra malaria deaths in a century cases through expensive CO2 cuts, maybe we should avoid a million malaria deaths now through low-cost health policies.
Tickell's reply clearly shows what happens when policy drives the search for suitable facts. The IPCC is simply ignored, Stern is praised for his policy usefulness, Weitzman embraced irrespective of his analysis essentially leading to policy paralysis, driven by extreme and pervasive speculative risks. Not surprisingly, Tickell ends by saying – without a shred of evidence – that his policy would be the best solution, "even without the threat of global warming".
Not only does Tickell abandon his central claim of human extinction, but he also abandons his entire argument for his policy. Not much remains.