
Gavin [Correction: David] over at RealClimate has taken up Paul Krugman’s recent NY Times Magazine piece — which is a very good piece, IMHO, and I’d like to say more about it in a bit…but not here, dear readers — and if you haven’t yet, you should head over there and do so. The comments, as usual, are also worth the read. One point of note, however, was Gavin’s observation:
[Krugman] also seems to have missed the recent revelation that what really matters to climate is the total ultimate slug of emitted CO2, implying that unfettered emission today dooms us to more drastic cuts in the future or a higher ultimate atmospheric CO2concentration, which will persist not just for “possibly centuries”, but almost certainly for millennia.
I have a paper on a related topic that is currently making the referee rounds. In that paper, I engage the question of causal impotence — an esoteric discussion in applied ethics — but I also discuss what I think is a fundamental rift within the climate community. It’s evident right here, right in the first paragraph of the RealClimate post.
Namely, Krugman is an economist. He thinks in terms of costs and benefits, where these are characterized as units of welfare or preference satisfaction. It is entirely likely, therefore, that he’s thinking about mitigation in terms of “harms to people” or “harms to the economy.”
Gavin David, by contrast, is a climate scientist. He thinks in terms of climate systems and damage to, or interruptions in, those climate systems, where these are characterized as degrees from normal, deviations from expectations, and so on. It is entirely likely, therefore, that he’s thinking about mitigation in terms of “harms to the climate,” or some such.
This ambiguous focus of the climate discussion is, to my mind, a major rift that needs rifling through. As it happens, it’s primarily a philosophical discussion about ‘harms’, but it would behoove everyone to get clear on what, exactly, we’re talking about. We only vaguely know what we mean by a ‘harm’, and so far as I can tell, nobody’s bothered to spend much time exploring the issue.
If this were only an intellectual exercise, I suppose it might be one thing. But this is not a mere intellectual exercise. It has real-world implications. As a consequence of this ambiguity in the notion of ‘harm’, we’ve also not been particularly clear about what we mean by ‘mitigation’. I suspect that our lack of clarity gives rise to all manner of criticisms from all manner of quarters, including the Björn Lomborg sort. You see conflicts of the same sort appearing in the AR4 versus the Stern Review report.
Having said this, Roger also recently picked on Krugman’s piece as being muddied and confused, particularly with regard to alternative technologies. I personally don’t care much for the standard economic line on the environment, so I’m not, strictly speaking, a fan of Krugman’s suggested approach here. (I disagree with the reasoning, not the proposal; and there’s a lot about Krugman that I do like.) At the same time, I think it’s not entirely true that Krugman is guilty of the muddying and confusing that Roger thinks he is.
Simply because Krugman leaves the question of energy technology out of the discussion doesn’t undermine other reasons for promoting conservation — maybe, for instance, it is just reckless or greedy not to conserve. In this case, one can find a rationale for promoting conservation through economically grounded policy incentives without appeal to alternative technologies. To be more specific, Krugman isn’t just talking about decarbonizing the economy, he’s talking about conserving the energy resources that we have. That, I think, is also an area toward which the discussion could be moved.