Thanks. Yes, you are correct about the acceptance. I am assuming that if there are radically novel papers in the pipeline I would have heard about it among the hurricane community, but you are right, there always may be unanticipated surprises.

The longer the time horizon, the greater that the analysis falls in favor of the societal factors. This is because vulnerability is doubling every 7-15 years, while the projected increase in hurricane intensity is measured in tens of percent over the same time frame. So as we go from 2050 to 2100 wealth and population will double at least 2 times (a 200% increase), while hurricane intensity is currenty expect to increase by less than 5% over that same time period. But assume that these estimates of intensity increases are in error by a factor of 3 (i.e., 15%), or 5 (25%) even (unrealistic given current understandings, but assume it anyway). It does not change the qualitative interpretation of the results. This is a pretty robust conclusion.

Yes, I think that sea level rise was considered in the integrated assessment model studies that we surveyed, but it can’t be too significant of a factor in damages. Consider that the IPCC projects sea level increases of 0.25 to 0.45 meters by 2100, while a storm like Katrina had a storm surge of 10 meters in some places. I doubt that damage would have been measurably different if this had instead been 9.5 or 10.5 meters. If you can identify a signal of sea level rise in the damage record over the past 100 years, then you might have a case for its importance.

In any case I look forward to your longer post.

Thanks!

I need to do a longer comment on all of this, but if your new effort both uses a 100-year horizon and considers the enhancement of storm surge by sea level rise (did the first one?), can you be so confident about the conclusions?

Thanks for the follow up.

You correctly saw the 40-50% figure referenced in our paper to the various integrated assessment studies, but we did not use these figures in our calculations because the IPCC provided updated and more authoritative estimates for projected hurricane intensity.

Specifically, on p. 260 of the article we describe the methodology used by each of the integrated assessment models for calculating the sensitivity of losses to climate change influences on hurricanes, and summarized in Table 1. Each of these methods assumed a 40-50% increase in the intensity of hurricanes to 2050. (We used 2050 because that is what the IPCC SAR used. Obviously one could use whatever end date one wanted to in such an analysis, providing that the proper information is available, e.g., from the IPCC.) The IPCC SAR WG I concluded that hurricane intensity would increase by 10% by 2050, so we used this figure in the damage formulas presented by Tol, Fankhauser, and Cline under the assumption that the IPCC represented the most updated and accurate state of the science. On page 264 we show that the damages under such a scenario would increase by 8-10% under the three integrated assessment methods.

Thus, the 22 to 1 figure comes from (32 billion (A2 scenario) – $10 billion (base))/1 billion (Cline estimated increase). Similarly the 60 to 1 figure comes from (58 billion (A1 Scenario) – $10 billion (base))/0.8 billion (Tol estimated increase).

As far as updating the analysis, currently the state of the science would lead to numbers more like 50 to 1 and 130 to 1! Consider that Knutson and Tuleya (2004) provide a scenario that suggests a 5% increase in hurricane intensity by 2080, which is 30 years later than IPCC SAR estimated and half the intensity increase. Of course, scientists may come up with other estimates that are larger in the near term, but these results are not really sensitive to whether it is 5% or 50%, given that population and wealth are doubling in coastal locations every 7-15 years. Redoing this analysis when the next IPCC makes sense, but because the IPCC has not updated the SRES scenarios, the wealth and population data will not change from the 2000 study, and because the IPCC is only supposed to use peer-reviewed work published as of Dec, 2005, I think that the Knutson and Tuleya article will be among the most recent and authoritative. Thus, our next analysis may make the 2000 study look conservative by comparison.

Thanks!

More later, but I’ll just note squeakily here that the alleged error of a 40-50% increase in intensity from warming “repeated throughout Schmidt’s post,” is taken from your original article.