For some odd reason the question of the linkage, or otherwise, between hurricanes and global warming is in the news at the moment. As to the details, I have rather little to say, on the grounds that hurricanes in the Antarctic are unknown. I will recommend this RC post if you're interested; also RP Jr has quite a bit to say about the issue recently. But I do want to make a comment about the attribution question. As far as I can tell, while its premature to say: "an increase in hurricanes can be attributed to global warming", its equally wrong to say "global warming has had no effect on hurricanes".
Which is why I find RP Jrs latest rant on ceding the high ground odd, because he apparently approves of James Glassman at TCS who sez Katrina has nothing to do with global warming. Nothing. Approving of anything on TCS is a strange thing to do, and I can't see why this one should be approved of. It looks like some kind of reverse-fallacy to me: failing to attribute to GW doesn't do the reverse, ie it doesn't demonstrate a lack of connection. Is it perhaps the "unexcluded middle" fallacy?
Having said that, the perceptive will notice that I welcome RP Jr back onto my blogline, and Sr (and not just because I got him to nuance his nuances a bit more).
William- Well, part of citing JG was in fact to provoke, and I see that it did ... but I think that Occam's razor would suggest that we start with a hypothesis that global warming is not having an effect, and then seek to falisfy that hypothesis, which has not yet occurred. As you may have seen in our BAMS paper, I am not in any way opposed to the idea that GW may in fact have already or in the future affected hurricanes, but I'd like the science to be there first. From the standpoint of policy and societal impacts, the connection is under any reasonable interpretations of current scientific understandings moot. There is no basis for claiming that GHGs are an effective tool for disaster management ... Thanks, Roger
John Fleck said....
Farbeit from me to defend Glassman, but I think Roger was not trying to defend Glassman on the narrow note you quoted, but on the broader critique of those like Gelbspan who are trying to situate Katrina as a token in the climate wars. I think any reasonable reading of the literature here suggests that what Gelbspan wrote (and others writing similarly) is inappropriate.
Yes, I agree with all that. But I think you are effectively conceding my point: that proving that GW has *not* had an effect has not been done. Which makes Glassmans piece wrong, especially as he states the lack of connection as absolute. I know what youre trying to say, but asserting that Glassman has taken the high ground is IMHO indefensible.
I'm not (at least here) asserting anything terribly policy relevant about this: I'm saying that Glassman is *wrong*, just as someone who says "Katrina was definitely caused by GW. Totally" is also wrong.
Oops, sorry, previous response was to RP. To John: I see what you're saying. I haven't personally read anything (other than in sci.env, but you can find anything there) that says what RP is criticising the liberal left for, but I wouldn't be surprised if someone has. I like and agree with RP's fudging post. Todays Grauniad article in the science section here seems OK to me.
All I'm trying to say here is that the assertion that Glassman has the moral high ground appears wrong to me: Glassman is as wrong as those he is criticising.
Now *I'm* going to write something in praise of RP. From his file here look at fig 6, which compares the damage estimates to 2050 from societal changes and GW changes.
I'm sure there is wiggle room for exactly how big the various estimates should be, but that appears to indicate pretty clearly that societal impacts are far more important. Interesting.
Roger said, "but I think that Occam's razor would suggest that we start with a hypothesis that global warming is not having an effect, and then seek to falisfy that hypothesis, which has not yet occurred." I don't think that's the appropriate spot to start, myself. To me, the appropriate starting point is that we have no idea if, or if not, there is an effect and that the nature of the observational data set and physical processes means that we are unlikely to know. It's similar to the severe thunderstorm problem. I can argue (with a straight face) for increases or decreases in frequency based on fairly basic principles, but the observational database of events is so poor we couldn't identify even relatively large changes. This is different from the problem, say of temperature changes, where the observational record is better and there's a clear physical mechanism.
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