An “Emerging Consensus”, part XVI

Interesting comment from Kevin Vranes that’s worth pulling out onto the front page. The question is whether there’s really an “emerging consensus” on the hurricane-global warming link. Kevin’s privy to discussion not visible to us plebes:

I still have to say that after watching the emails fly on the tropical cyclones email list over the past two weeks, a list that contains almost everybody of importance working on tropical cyclones in the world and to which Holland, Curry and Webster have also been posting in the past two weeks, anybody would be very hard pressed to say that an “emerging consensus” exists amongst that group of experts. Mostly what I’ve seen are very reasonable, very well-considered emails poking major holes in the data Webster used, among other aspects to the “debate.”

I’ll continue to maintain that while it is very reasonable to infer that increased global T –> stronger hurricanes, “reasonable” means nothing in systems that can be as counter-intuitive as climate/weather.

I continue to wonder what the hurry is. Science is hard, sometimes it takes a while to figure stuff out, and I’m at a bit of a loss to imagine what difference it makes, in terms of the actions we might take, whether we know the answer to this question now, or next year, or in 2011.


  1. To know what this really means one would have to know exactly who is on that list and who has been making those comments. In-house HRD theologian Stan Goldenberg, e.g.? Snark aside, it’s interesting to see exactly who is on the AGW side, via either publication or public statement, vs. who on the Gray/NHC side. Things are very lopsided in terms of numbers, and if we add a weighting for CVs it gets a lot worse.

    Regarding the specific issue, it’s well-known that the NHC data Webster et al had to work with had holes. The data is currently being re-worked by Chris Landsea (it’s a small world after all). Landsea has stated that he expects the new data will show a substantially greater number of strong hurricanes in the earlier part of the study period (roughly 1950-75), which will affect Webster et al’s results. Webster agrees that this is true, but points out that a change large enough to affect his conclusions is highly unlikely.

    Why it matters should be clear enough: Very large land use decisions adding development to hurricane-vulnerable portions of the Gulf and Atlantic coasts continue to be made on the assumption that the current level of storms will drop again in the not too distant future. If the government would say instead that the current level is very unlikely to drop, and if anything will go up, I think we’d be seeing a quite different response. What’s at stake here are billions of dollars and hundreds of lives.

    On a political level, it’s depressing to see Bush political appointees get away with enforcing silence on scientists who otherwise would be telling the public that there is every reason to not expect a reduction.

  2. Correction: The first half of the Webster et al study is about 1970-86. To expand slightly on what I said before, to throw off Webster et al’s conclusions would require the promotion of about 9 hurricanes per year from minor to major status, which is a huge change.

  3. Steve –

    I’m curious as to the evidence supporting your asssertion that, “Very large land use decisions adding development to hurricane-vulnerable portions of the Gulf and Atlantic coasts continue to be made on the assumption that the current level of storms will drop again in the not too distant future.”

    Who is making that assumption, and how are they articulating it?

  4. I would be very surprised to see it articulated out in the open, although OTOH I suppose it’s hard for them to ignore the issue completely. I’ll check and see what I can find on this.

    My evidence is the lack of large coastal developments being cancelled. I think the key point is that if for any given development the likely return period for a hurricane is substantially more than the 10-15 period of heightened activity imputed to “natural cycles,” the developer (and local land use authorities) will ignore the heightened short-term risk. Large developments often get planned within similar time-frames, which is to say developers are used to buying property and then waiting 10-15 years before actually breaking ground. All of that said, if we start having repeats of the 2004/5 seasons on a regular basis, I don’t think it will take long for the effects of an inability to obtain insurance in vulnerable areas to kick in (although I suppose the cynical POV would be that state insurance funds will step in even though they likely won’t be sufficiently capitalized to pay for the consequences of a big strike or strikes).

  5. of course it matters who is on the list, but as I said, as far as I know it’s just about everybody in the universe doing work on tropical cyclones, including the major names in the news over the past year. Keep in mind that relatively very few people are actually doing work on hurricane climatology (this was Judy Curry’s point in attacking Bill Gray a few months ago — that she and her team are actual climatologists rather than just hurricane forecasters) — but the prominent ones that are doing climatology have been contributing to discussions on the list.

  6. Could you be a little more specific about what holes have been poked in Webster et al’s data? I won’t ask who made them, but I wouldn’t put a lot of stock in those assertions if they come from people without specific direct knowledge of substantial numbers of extra major hurricanes in the period at issue. Put another way, what data has been provided to back up those assertions?

  7. Just saw this interesting story in the Maimi Herald featuring Chris Landsea’s response to the new Trenberth-Shea paper: . Excerpt:

    “Chris Landsea, a leading hurricane researcher and the science and operations officer at the National Hurricane Center in West Miami-Dade, maintains there is no proven link between global warming and the number of storms — and only a tiny link to the intensity of storms.

    “He and some others believe that unusually vigorous hurricane activity since 1995 has been caused mostly by long-term natural cycles largely unrelated to global warming.

    “Landsea, an official scientific reviewer of the Trenberth-Shea report, was uncomfortable with at least one of its statistical methods.

    “‘This report does make a contribution to the science, where it’s helping to partition out natural [cycles] and global warming when it comes to ocean temperatures,’ Landsea said. ‘But the implication for hurricanes is not nearly as straightforward as they are suggesting.'”

    Now this is an interesting twist! Landsea seems to have abandoned the natural cycle theory as regards SSTs, but now seems to assert that the cycles are largely controlling of hurricane trends via other factors. I had thought this argument would be largely over when the natural cycle crowd accepted the AGW-SST connection, but apparently not. I will await with bated breath the paper supporting Landsea’s views.

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