Monday, January 22, 2007

Thomas Knutson is a very dangerous guy...

A while ago Eli pointed to a 2005 article by Thomas Knutson and Robert Tulyea on hurricane modeling as an example of fine climate snark

Michaels et al. (2005, hereafter MKL) recall the question of Ellsaesser: “Should we trust models or observations?” In reply we note that if we had observations of the future, we obviously would trust them more than models, but unfortunately observations of the future are not available at this time.
the Kappa and the Lambda being Knappenberger and Landsea. But this, dear friends was but a small beginning. The subject was whether CO2 forcing would change the nature and frequency of hurricanes and how climate models could be brought to bear on the question, you are free to guess who took the affirmative.

While the comment itself and the underlying papers (curl up with a good journal and rtfr dear bunnies) are interesting in and of themselves, and more usefully as background to the current hurricane wars (other papers on the subject by Knutsen are also good) Eli came back to this in answer to some back and forth on Roger Pielke Sr.'s blog. Roger, Sr. has both a certain style, and a bunch of obsessions, but he also tends to force the cards, looking at only one side of the equation. In commenting on Michaels, Knappenberger and Landsea (MKL), Knutson and Tulyea pretty much spot the pea under the shell:
In contrast to Michaels et al., who exclusively emphasize uncertainties that lead to smaller future changes, uncertainties are noted that could lead to either smaller or larger changes in future intensities of hurricanes than those summarized in the original study, with accompany in smaller or larger societal impacts.
As in
We noted in KT04 that there is uncertainty concerning future changes in atmospheric temperature profiles and other factors such as vertical wind shear, which could affect storm intensities. In contrast to MKL, who evidently believe that these factors will change in such as way as to oppose future SST-driven intensity increases, we note that these factors could change in ways that either reduce or enhance the increases of intensities that we simulate. Uncertainties such as these are a “two-edged sword”—not the panacea envisioned by MKL.
MKL are not very impressed by models
MKL contend that the model used in KT04 has no intensity forecasting skill and therefore is of limited utility in studies of future climate change impacts on hurricane intensity. In doing so, they fail to recognize the important distinction between the operational hurricane forecasting problem (a classical initial value problem) and the boundary value problem addressed in KT04, where one is concerned with the maximum hurricane intensity that is possible for a given set of largescale environmental conditions (i.e., a climatological or statistical distribution of maximum intensities).
Eli notes that this confusion about the nature of boundary value problems and model skill appears endemic to the Eastern Slope of Colorado

Knutson and Tulyea end with a crescendo
MKL propose to adopt what appears to be a plausible but low-end scenario of future radiative forcing, whereas Houghton et al. (2001) indicates that even stronger radiative forcing scenarios than we use in KT04 are also plausible. MKL present a flawed SST– intensity regression analysis comparing correlations of real-world intensities versus SST with idealized model correlations where no synoptic weather variability is present. Interestingly, their noisy regression (slope) results hint at a much greater sensitivity of hurricane intensity to SST than our simulations.....


Anonymous said...

One interesting question about MKL is why that journal article didn't contain a conflict of interest statement since Michaels and Knappenberger are swimming in corporate cash.

Anonymous said...

I have never been able to figure out what the hurricane forecasts are useful for -- other than to test models (and for that, real after the fact data is much more useful).

The forecasts are often completely wrong (as they were for the Atlantic this past summer) and in any given year, different people (or groups) often produce very different forecasts.

So hurricane forecasts have more than a little in common with reading tea leaves. They are about as reliable and therfore about as useful.

Anonymous said...

Thats Crescendo, not Creshendo.
Did you ever play a musical instrument?

EliRabett said...


Anonymous said...

I believe "Creshendo" is the unceremonious removal of the Christmas Cresh (or Creche, for purists) from the village square after complaints from the local chapter of AA (Atheists Anonymous).

Which instrument? The pickelo?