Flawed study on impact of climate change on damages from Atlantic hurricanes ignores one of its own references and many key factors
Anthropogenic climate change will almost certainly increase the number of the most destructive hurricanes (see “Nature: Hurricanes ARE getting fiercer “” and it’s going to get much worse” and NOAA here, the source of the figure).
Also, while this has not been modeled much, warming will put more water in the air above the ocean for hurricanes to sweep up and deluge down, as Kevin Trenberth, head of NCAR’s Climate Analysis Section, explains here.
A trickier question is how that will translate into an increase in landfilling hurricane and, even trickier, how much that will translate into increased damage, when you have to correct for non-climatic factors that would increase damage (population and GDP growth) and those that would decrease damage (better hurricane warning and building codes). Hurricanes are uniquely difficult to do this kind of analysis for because, as Judith Curry has pointed out, “It’s the strongest storms that matter most.”
“More than half the total hurricane damage in the U.S. (normalized for inflation and populations trends) was caused by just five events,” explained MIT hurricane expert Kerry Emanuel in an email to me a while back. Storms that are Category 4 and 5 at landfall (or just before) are what destroy major cities like New Orleans and Galveston with devastating winds, rains, and storm surges. One extra Cat 4 or 5 hitting Miami and you’ve obliterated the damage records.
So one thing you can safely say about a hurricane damage analysis study: Its conclusions should not be generalized into broader conclusions about the impact of climate change on extreme weather.
Into this mix comes a new study, “Emergence time scales for detection of anthropogenic climate change in US tropical cyclone loss data,” by Crompton, Pielke and McAneney (PDF here via the NYT/ClimateWire article). Yes, it’s that Pielke (see Foreign Policy’s “Guide to Climate Skeptics” includes Roger Pielke, Jr.), who just can’t avoid making an outrageous and baseless attack on the integrity of those whose real-world data happen to disagree with his widely-criticized modeling:
The study concludes, unjustifiably, as we’ll see:
Recent reviews have concluded that efforts to date have yet to detect or attribute an anthropogenic climate change influence on Atlantic tropical cyclone (of at least tropical storm strength) behaviour and concomitant damage. However, identification of such influence cannot be ruled out in the future. Using projections of future tropical cyclone activity from a recent prominent study we estimate the time it would take for anthropogenic signals to emerge in a time series of normalized US tropical cyclone losses. Depending on the global climate model(s) underpinning the projection, emergence time scales range between 120 and 550 years, reflecting a large uncertainty. It takes 260 years for an 18-model ensemble-based signal to emerge. Consequently, under the projections examined here, the detection or attribution of an anthropogenic signal in tropical cyclone loss data is extremely unlikely to occur over periods of several decades (and even longer). This caution extends more generally to global weather-related natural disaster losses.
As we’ve seen, the big city-destroying hurricanes are such unique events, whose damage is highly dependent on even a small change in storm track, that one should be very reluctant to generalize any modeling conclusion about the damage they might cause to “global weather-related natural disaster losses.” This goes double for a study that ignores key damages caused by hurricanes and weather-related disasters.
Crompton, Pielke and McAneney (CPM) note on page 4:
Our study ignores future rising sea-levels and related adaptation efforts, both of which will be important for damage arising from storm surge, as well as any future changes in tropical cyclone rainfall.
But increases in rainfall intensity are a big deal. And as we saw with Katrina, the devastation caused by the storm surge to a city that is below sea level may be the single biggest threat that hurricanes pose in the future.
The authors’ rationalization is “With respect to these issues, we note that the historical damage record compiled by the US National Hurricane Center generally does not include losses associated with rainfall-induced flooding.” So what? These omissions alone call into question the results — and certainly should have led the authors and the reviewers to avoid generalizing these now somewhat arbitrary results to all global weather-related natural disaster losses.
I would add that today, the part of our coast that hasn’t been eroded by storm and tide has generally been toughened up by them. Sea-level rise exposes parts of the shore to storms that are not so strengthened. So even a foot of sea level rise could well increase the damage of major hurricanes substantially, let alone the several feet we may say in the second half of the century (see Sea levels may rise 3 times faster than IPCC estimated, could hit 6 feet by 2100).
Trenberth in his review of Pielke’s book in Science (subs. req’d) notes other flaws in Pielke’s general methodology for looking at hurricane damages:
He makes “corrections” for some things (notably, more people putting themselves in harm’s way) but not others. Some adjustments, such as for hurricane losses for the early 20th century, in which the dollar value goes up several hundred-fold, are highly flawed. But he then uses this record to suggest that the resulting absence of trends in damage costs represents the lack of evidence of a climate component. His record fails to consider all tropical storms and instead focuses only on the rare landfalling ones, which cause highly variable damage depending on where they hit. He completely ignores the benefits from improvements in hurricane warning times, changes in building codes, and other factors that have been important in reducing losses.
But let’s go back to the first sentence in CPM’s abstract, “Recent reviews have concluded that efforts to date have yet to detect or attribute an anthropogenic climate change influence on Atlantic tropical cyclone (of at least tropical storm strength) behaviour and concomitant damage.”
Compare that to the conclusion of CPM’s reference 8 — Schmidt, Kemfert and H¶ppe, “Tropical cyclone losses in the USA and the impact of climate change “” A trend analysis based on data from a new approach to adjusting storm losses” (subs. req’d):
In the period 1971-2005, since the beginning of a trend towards increased intense cyclone activity, losses excluding socio-economic effects show an annual increase of 4% per annum. This increase must therefore be at least due to the impact of natural climate variability but, more likely than not, also due to anthropogenic forcings.
That isn’t definitive attribution — which the authors explicitly avoid — but it still is a statement of attribution. Since CPM cites the paper but doesn’t refute it, they undercut their own conclusions.
For the record, Pielke himself told Nature back in 2006:
Clearly, since 1970, climate change (i.e., defined as by the IPCC to include all sources of change) has shaped the disaster loss record.
Yes, that is what Pielke said (see Pielke in Nature: “Clearly, since 1970 climate change “¦ has shaped the disaster loss record”). You can look it up yourself: The PDF of the Nature story, “Insurers’ disaster files suggest climate is culprit,” is here.
Of course, not all climate change since 1970 is due to humans, but the U.S. National Academy of Sciences concluded its recent review of climate science, saying it is a “settled fact” that “the Earth system is warming and that much of this warming is very likely due to human activities.”
So if you want to play word games and perform analyses that ignore key impacts of climate change (among other flaws) in order to make a relatively pointless point, well, that is your right. But the rest of us can be quite confident that humans are changing the climate and that it is showing up in the disaster record and it is going to get much, much worse if we don’t act soon.
How confident can we be? Munich Re, one of the world’s leading reinsurers, issued a news release in late September, “Large number of weather extremes as strong indication of climate change,” which noted:
Munich Re’s natural catastrophe database, the most comprehensive of its kind in the world, shows a marked increase in the number of weather-related events. For instance, globally there has been a more than threefold increase in loss-related floods since 1980 and more than double the number of windstorm natural catastrophes, with particularly heavy losses as a result of Atlantic hurricanes.
The rise in natural catastrophe losses is primarily due to socio-economic factors. In many countries, populations are rising, and more and more people moving into exposed areas. At the same time, greater prosperity is leading to higher property values. Nevertheless, it would seem that the only plausible explanation for the rise in weather-related catastrophes is climate change. The view that weather extremes are more frequent and intense due to global warming coincides with the current state of scientific knowledge as set out in the Fourth IPCC Assessment Report.
There are at present insufficient data on many weather risks and regions to permit statistically backed assertions regarding the link with climate change. However, there is evidence that, as a result of warming, events associated with severe windstorms, such as thunderstorms, hail and cloudbursts, have become more frequent in parts of the USA, southwest Germany and other regions. The number of very severe tropical cyclones is also increasing. One direct result of warming is an increase in heatwaves such as that experienced in Russia this summer. There are also indications of a higher incidence of atmospheric conditions causing air mass formation on the north side of the Alps and low-lying mountain ranges, a phenomenon which can result in floods. Heavy rain and flash floods are affecting not only people living close to rivers but also those who live well away from traditionally flood-prone areas. Although climate change can no longer be halted, even with the help of very ambitious schemes, it can still be curbed.
Dr. Peter H¶ppe, Head of the Geo Risks Research Department at Munich Re, the co-author of Schmidt, Kemfert and H¶ppe, wrote me:
For me the most convincing piece of evidence that global warming has been contributing already to more and more intense weather related natural catastrophes is the fact that while we find a steep increase in the number of loss relevant weather events (about tripling in the last 30 years) we only find a slight increase in geophysical (earthquake, volcano, tsunami) events, which should not be affected by global warming. If the whole trend we find in weather related disaster should be caused by reporting bias, or socio-demographic or economic developments we would expect to find it similarly for the geophysical events. By the way the assumption that climate change is increasing the risk of extreme weather events is backed by IPCC.
This is all one big coincidence for the anti-science disinformers. But for the rest of us, more and more studies keep coming out attributing extreme weather events to climate change (see Study: Global warming is driving increased frequency of extreme wet or dry summer weather in southeast, so droughts and deluges are likely to get worse).
The really scary part is that we’ve only warmed about a degree and a half Fahrenheit in the past century. We are on track to warm five times times that or more this century (see M.I.T. doubles its 2095 warming projection to 10°F “” with 866 ppm and Arctic warming of 20°F ). That outcome is especially likely if we listen to the do-little crowd of confusionists — see Finally, Roger Pielke admits he supports policies that will take us to 5-7°C warming or more).
In short, we ain’t seen nothing yet — and we won’t have to wait a century to figure out that humans are the cause!
UPDATE: Contrary to what you may read on the blogosphere, no one has ever contacted me with an offer to debate for charity, even many months after I noted that fact. In any case, I have explained at great length why one doesn’t debate folks like Pielke (see “Debate the controversy!“). To paraphrase Juan Cole’s advice to climate scientists on how to avoid being Swift-boated, any debate or broadcast that pits a serial misinformer or misrepresenter against someone defending climate science is automatically a win for the misinformer, “since a false position is being given equal time and legitimacy.” That’s why 99% of the articles or blog posts you read by people demanding some climate science defender debate someone are by other serial misinformers.
For more evidence of why why one doesn’t debate folks like Pielke, consider this jaw-dropper in the NYT/ClimateWire story:
“If you have a vested interest in particular outcomes, you want to try to emphasize that science or that information that best makes your case,” Pielke said of Munich Reinsurance and other companies that emphasize addressing climate change. “If there’s an expectation that losses over the next few years are going to be higher because of climate change, it provides a scientific, quote-unquote, basis for justifying rate increases.”
“Because your credibility is hard to gain and easy to lose in the area, and they don’t want to be seen as going beyond what the science can support,” he cautioned.
Yes, Pielke is accusing Munich Re of bad faith analysis, of making the data-driven assertions they have solely to make more money — without any justification whatsoever for such an incendiary charge! And remember, this is all because their real-world data happen to disagree with Pielke’s own flawed modeling, which has been critiqued by some of the leading experts in the field. For the record, Munich Re is one of the most respected companies in the industry.
Pielke made the same exact kind of baseless smear against IPCC chief Pachauri (see here), which led climate scientist Ken Caldeira to email me a long defense of Pachauri ending “For a man with a $49,000 salary, donating all of his consulting fees to nonprofit organizations would ordinarily be seen as a sign of professional integrity and dedication. It is outrageous that Pielke attempts to turn this around and use it to insinuate an ethical lapse. It makes one wonder about Pielke’s motives.” Pachauri was ultimately vindicated (see “KPMG review finds IPCC chief Pachauri innocent of financial misdealings or conflict of interest, UK Telegraph apologizes for smearing him“).
Or you can look at this 2009 ScienceBlogs post, “Pielke Jr: How low can he go?” from A Few Things Ill Considered: “His [Pielke's] latest effort at sabotaging productive discourse on climate science and policy is a really low blow, putting to rest any lingering hopes one might have had that he still had some integrity stashed away in there somewhere. Now I know these are strong words, but I have to confess this really gets my blood pressure up, it is just the slimiest of tactics.”
Computer scientist Tim Lambert (aka Deltoid) has a whole category just for Pielke, which I commend to anyone who still thinks he is a serious representative of science or even climate analysis, someone who anyone should debate on any circumstances.
Significantly, Pielke agrees with the rest of his field on the need to stop emitting carbon dioxide and to stabilize its concentration in the atmosphere at somewhere between 350 and 500 parts per million; he just doesn’t want scientists to tell the rest of us how to get there.And so with all the “debunking” of prominent science, by the book’s end his readers won’t have learned very much at all. If you didn’t know that there were uncertainties in climate science before, then yes, you will definitely know that now. Pielke’s actual “fix,” on the other hand, comes so late in the book and is so poorly highlighted that it might not get noticed at all.
What is that fix? Well, it involves an obscenely low price on carbon (US $5 per metric ton) that will pay for further innovations in renewable energy. Other than that, Pielke advocates setting specific goals, monitoring progress, and focusing on technology advancement. Yawn.
If Pielke’s first tenet is the completely unrealistic and potentially counterproductive divorce of science from policy, his second, as evidenced by the meager carbon price, seems to be aiming low in the name of political expediency. He suggests five bucks only because it seems feasible and cites the support of Exxon Mobil’s CEO as evidence. Seriously, Exxon Mobil. “The precise amount of the tax itself””whether $5 per metric ton, or $10, or only $3″”is less important than that the tax be implemented at the highest price politically possible,” Pielke writes.
Such “pragmatism” amounts to bargaining ourselves down in advance of the bargaining that we have to do with others. Pielke’s carbon price will force fossil fuel companies like ExxonMobil to do absolutely nothing differently. Pielke admits this, noting that the point is simply to raise money for renewable energy technology innovation. Such a path, though, ignores the vast scientific consensus that we need to start lowering emissions yesterday. Even if his carbon tax could raise $150 billion per year, as Pielke suggests, the pace of innovation can’t match the pace of current emissions and subsequent temperature and sea level rise, ocean acidification, and various other problems. At its root, Pielke’s climate fix is to do almost nothing.