Monday, 15 February 2010

More Inaccurate Truths?

Sigh. Another day, another Guardian article on climate change inaccuracies (though this particular brouhaha has been in the news for a little while now). Seeing as how a lot of people are now breaking out the party hats and dancing on the grave of man-caused climate change, it might be wise to take a breath and consider where we actually are right now.

One of those times I found it most difficult to understand the thought processes of climate change skeptics/deniers[1] was during the flap over the nine "inaccuracies" in Al Gore's film An Inconvenient Truth. I put the word inaccuracies in quote marks mainly because a review of the nine points reveals a significant variation in how reasonable the term is. Some of them are clearly mistakes, others seem to involve the judge quibbling over the differences between possible, plausible and probable events, and whether or not sufficient evidence exists for what he believes Al Gores intended to imply to the audience. I don't want to get into an argument over whether we should allow judges to determine the validity of statistical conclusions, but it's at least arguable that three or four of the highlighted "errors" aren't really anything more than semantic arguments regarding the level of certainty with which the judge believes a given statement can be made compared to the level of certainty with which he believes Al Gore had made it, and one (the CO2 graph) that I think the judge is dead wrong on in any case.

That's not really the point, though. The point is that a fine-tooth comb analysis of the film revealed nine facts that could be refuted, quibbled with, or cast in alternative lights, to the point where they needed to be addressed. What I can't get my head around is skeptics cheering these flaws in the film, rather than turning white with terror that the detailed, in-depth analysis of the ninety minute film (I guess the slide-show itself is about an hour or so) had determined that everything else in it was true. Either the claimant's experts had decided not to challenge any other point, or they had and the judge had ruled that point was sufficiently backed up by the evidence. The judge went so far as to say "I have no doubt that Dr Stott, the Defendant's expert, is right when he says that: 'Al Gore's presentation of the causes and likely effects of climate change in the film was broadly accurate.'"

It seems to me only the most lunatic of head-in-the-sand deniers could see that film and argue there wasn't anything to worry about because it was merely broadly accurate.

I mention all this because it's been looking a great deal like something very similar is going to happen again. This time, it's the IPCC report that's under fire, for including an unchecked prediction on how quickly the Himalayan glaciers will melt, including the hockey stick graph that is at the heart of the "climategate" screaming match, and (perhaps most ridiculously) misquoting the percentage of The Netherlands currently below sea level.

The first and third are clear mistakes (frankly, I can believe the latter is a simple typo), and it speaks poorly of those that composed the report allowed them to slip through. Both of them exist on the very fringe of theory, however. Getting either statistic wrong makes very little difference, because the former comes at the end of the process (prove the existence of climate change, demonstrate the degree to which its our fault, extrapolate what our continued actions will result in, and only then estimate how quickly the glaciers will melt), and the latter is only relevant if one believes that policy makers (or the general public) could be compelled to action in order to prevent half a country flooding, but not merely a quarter.

The hockey stick issue is more concerning, and I'm still digging through it all. To digress slightly, the problem here is that there are three separate issues that we must be careful not to conflate: 1) Is the previous methods by which that data was analysed objectively inferior, or was it literally the best one could do with that set, 2) assuming the second is true, how much else has been built on that analysis, since everything that has can now be viewed as coming along with a label that says "assuming our best guess is true, it follows that..." 3) if that really is the situation, and we decide that we're either heading for total disaster or we'll be totally fine, how sensible is it to conclude that there is no point doing anything to avert disaster because we can only say "Our best guess is that we're fucked?". For the record, though, my current position is 1) there seems to have ultimately been consensus that it was the best one, though that doesn't make it good (the argument boils down to the method being unreliable over the short term for predicting temperature and thus unsuitable for longer time periods as well vs. it's better than nothing, and over the long-term the problems might iron themselves out), 2) not as much as people think; the hockey stick seems to be the most commonly cited evidence that current global temperature levels are unprecedented, which is a separate issue from why temperatures are so hot now ("It's happened before" is obviously a non-answer when you're trying to determine a specific cause), and 3) you'd need some fairly intelligent people and powerful mathematics to run the cost analysis to answer that one, and it wouldn't matter because people would automatically attack the answer if they didn't like it, just as they are doing now.

Anyway, the point here is that the IPCC report is now being taken apart, attacked by an entire fleet of fine-tooth combs. The skeptics are most certainly over it like white on rice, and if climate scientists have an ounce of sense, they'll be doing it as well. If follows, then, that within a comparatively short space of time (a year or so, perhaps) we will be able to divide the document into two classes: the parts which have been held up as dodgy, and those that haven't because no-one has been able to fault them.

This is why Ian Katz - whose heart I think is in the right place - gets it so wrong when he suggests the whole case must be remade (he's far more persuasive on the narrower issue of increasing public access to data sets). There's simply no need; what is and isn't correct will be determined pretty quickly, and my money is on the vast majority of cases falling into the former category. Did anyone demand we reconsider whether F=ma when Newton's conception of planetary orbits turned out to be flawed? The constant drumbeat of complaints along the lines of "If that's not true, what else might be false?" is deeply unconvincing precisely because those other areas can be checked as well. It's not like finding salmonella in a consignment of eggs. We can, and no doubt will, check the entire body of literature on this topic (or at least those parts of it that are heavily relied upon by the IPCC). The alternative framing of the situation, "If your investigation found that that's not true, then why couldn't you find a problem anywhere else unless no problem existed?" makes far more sense to me, but it's all too rare.

[1] And deniers are almost always what they turn out to be, in my experience. It is possible to be a global warming skeptic, I don't doubt, but every time I've seen such a person pushed to explain their skepticism, they always reveal that they are cheerfully, wilfully accepting of anything other skeptics have told them. You are NOT a skeptic if you're only skeptical about one side of a debate, especially when your "skepticism" is rooted in believing only one side has ulterior motives (how people can tell me with a straight face that scientists and governments are colluding in an international conspiracy to raise taxes whilst holding up big oil-funded research as evidence against AGW is simply beyond me). You're just a denier. You might not like the label, but that's the price you pay for deciding how trustworthy someone is based on how much you like what they're telling you.

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