“Climate change caused …”: linguistics, empirics, & reasoned discourse

Here are some reflections occasioned by (1) Andy Revkin’s excellent dotearth blog post on the relationship between climate change and Sandy; (2) the anger that Revkin’s post aroused among at least some climate-change-policy advocates, who proposed the laughable but still disturbing idea that Revkin be publicly censured in some way (others, it should be noted, responded in a critical but reasoned way to issues about advocacy and science information that are admittedly complex); and (3) a columin in the Huffington Post by George Lakoff, who has figured out that the problem here is confusion over language, which if used properly resolves important practical, empirical issues without the need to consult evidence (including evidence of how the public engages with climate science)…

There are 3 issues here: (1) one relating to whether “climate changed caused x” in general; (2) another to whether it caused Sandy in particular; and (3) a final one to the polemics of “caused by climate change…”

1. General.  Hansen et al. are much more helpful than Lakoff on this issue. When we ask the question, “did climate change cause x,” the issue is not “semantic” but practical & empirical: we want to understand what the physical relationship is between climate change & particular events &  what effect to assign to particular events in trying to asses the impact of climate change.  The issue isn’t what word or phrase to use; it’s what to do. Hansen et al. tell us *exactly* what we need to know: climate change shifts the normal distribution of weather events, making certain outcomes more likely & hence more frequent than they otherwise would have been. Accordingly, we can say that climate change made a particular event “y times more likely” than it would have been, if that’s useful (Hansen et al. identify events for which y is very very very high!); but more importantly we can speak instructively to the question of what the impact of climate change is in practical terms– “y more events like this per yr/decade, which will cost $z billion, kill q x 10^3 people  etc”.

It’s ironic that Lakoff refers to black-lung & cigarettes. The law got over being confused on causation for mass torts when it stopped trying to wring practical guidance from vague, impressionistic, & ultimately question-begging/-obscuring concepts like “direct vs. indirect,” & w/ the help of toxicologists, epidemiologists, economists & others started to think in practical, empirical terms akin to those being proposed by Hansen et al. At that point, the law adopted doctrines that made companies that manufacture products that increase the incidence of some harm pay the price of that extra harm w/o getting tied in conceptual knots about whether this particular actor “caused” that particular injury.

2. Sandy. I myself am still not sure whether climate change increased the likelihood of a weather event like Sandy. I would have thought the answer was clearly yes. But Revkin’s excellent dotearth post showed me that there is at least a division of opinion on this among experts; whether Sandy belongs to the class of events the likelihood of which was increased to a very high degree by climate change is not as cut & dried, apparently, as whether climate change increased the likelihood of, say, persistence of summer heat waves, or wild fires in western US.

But I might be misunderstanding & I’m sure there is more to day. I’d like to hear it. But I won’t if people agree to talk the way Lakoff does: whatever one thinks of his “systemic causation” linguistically, the way he uses it (“Global warming systemically caused the huge and ferocious Hurricane Sandy…”) begs the practical/empirical question.