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August 22, 2005

The Other Hockey Stick

Posted to Author: Pielke Jr., R. | Climate Change

Disaster losses have increased dramatically in recent decades. Yet as discussed here frequently there is no scientific evidence showing that any part of this increase can be attributed to changes in climate, whether anthropogenic in origin or not. This is a long post on this subject. It contains a lot of gory detail on what I consider to be a major misuse of science in the climate debate, viewed through the lens of a recent paper in Science. I focus on this issue mainly because this is an area where I have considerable expertise, and in this context my work is often mis-cited or ignored. This misuse of science is pretty much overlooked by scientists (here is one exception) advocates on either side of the debate, and the media (here is one exception). A number of colleagues and I have a letter on this subject coming out in the November Bulletin of the American Meteorological Society (I'll post a pre-publication version of this soon). Also, in partnership with Munich Re we are organizing a major workshop on attribution of causes underlying the observed trend of ever-escalating disaster damages. Munich Re seems very supportive of rigorous science on this topic. So clearly, I intend to pursue this subject.

Some important things to say before proceeding -- As I have written often on these pages, I accept the IPCC WGI consensus position on climate change and I am a strong advocate for policy action on climate change. I am also quite concerned by the role of science and scientists in the highly politicized context of climate.

I have titled this post "The Other Hockey Stick" drawing on some comments made by Hans von Storch in a talk at NCAR last month. The "other hockey stick" refers to the graph used by the IPCC based on Munich re data to show increasing disaster costs and has been widely used to argue for evidence of a climate change signal in disasters. Such claims are made by prominent scientists (such as Rajendra Pachauri and John Houghton) and can be found frequently in the scientific literature. The motivation for the present discussion is a paper in the 12 August 2005 issue of Science. Evan Mills, a scientist at Lawrence Livermore National Laboratory. Wrote in the essay,

"According to the latest Intergovernmental Panel on Climate Change (IPCC) assessment, climate change has played a role in the rising costs of natural disasters." And on the "relative weights of anthropogenic climate change and increased exposure" in the loss trend Mills concludes "quantification is premature." Mills uncritically accepts the IPCC statement, which as I show below is based on a pretty weak source and he is simply wrong on the latter point. Mills either ignores or is unaware of a robust literature on this subject (see here and here and here). Mills' analysis rests on a very thin basis of support. For reasons discussed below, it is amazing to me that Mills' paper survived peer review at Science. It should not have. Whether Science has a quality control problem or an inability to question analyses that may be politically inconvenient, the publication of Mills' paper sure does raise some questions.

Mills has a section of his paper focused on attribution of causes explaining recent trends in disaster losses. Let's take a close look at ten of the sources he cites in that section to support claims of a climate change signal in the damage record:

Kunkel et al. 1999. Mills cites this paper, (on which I am a co-author) to support this claim, "Socioeconomic and demographic trends clearly play important-and likely dominant-roles in the observed upward loss trends." Here is what Kunkel et al. concluded, "the results of the review strongly suggest that the increasing financial losses from weather extremes are primarily due to a variety of societal changes." Perhaps a slightly different characterization than the paper suggests, but lets move on.

Changnon and Demissie, 1996. This paper says nothing about trends in flood damage. What it does say is that in a comparison of urbanizing and rural river basins, there were large societal influences on streamflow in the urbanizing basins. This paper provides no basis for asserting anything related to flood damages.

Zhang et al. 2005. This paper is about the relationship of coastal erosion and sea level rise. It says nothing about trends in disaster losses.

Easterling et al. 2000. This paper states, "Most of the increase has been due to societal shifts and not to major increases in weather extremes. The growth of population, demographic shifts to more storm-prone locations, and the growth of wealth have collectively made the nation more vulnerable to climate extremes." This paper originated in a workshop held in Aspen that I participated in and I was originally a co-author on early drafts of this paper. I dropped off because I thought that the paper's conclusions were not supported by the evidence. In this case, there is an important difference in the cited sentence between the words "Most" and "All". "Most" happens to be grammatically correct, but in this case is synonymous with "All". My concern was that the paper would be mis-cited to assert an attribution when none was found. Here is a good example.

Karl and Trenberth 2003. This paper calls for the development of a global observing system. It says nothing about trends in disasters.

Next the paper asserts that "Global weather-related losses in recent years have been trending upward much faster than population, inflation, or insurance penetration, and faster than non-weather-related events (Fig. 2D). By some estimates, losses have increased by a factor of 2, after accounting for these factors plus increased density of insured values."

It cites 2 references to make this claim. The first reference is to a talk by Howard Kunreuther. I have known Howard for a while and respect him and his work a great deal. I emailed him to ask his source for this claim and interestingly he referred me to the second source cited by Mills. So Mills is citing the same source twice, using two apparently different sources. Not good.

The second source is a 2000 report by Munich Re on catastrophes. The relevant sections of the report can be found at pp. 79-81. Here Munich Re accurately cites my work to correctly argue for the normalization of historical loss data to account for societal changes. Then Munich Re provides some summary data following a black box calculation of changes in disaster damages after normalizing for societal changes. Munich Re finds that global disasters cost an adjusted $636 billion in the 1990s compared with $315 billion in the 1970s, and concludes, " Mills "factor of 2" comes from this calculation (i.e., 636/315).

Methodologically the calculation is suspect for a number of reasons. First, Munich Re provides neither their methods nor data. Second, Munich Re admits that data on changes in wealth are not available around the world and changes in GDP are not always a good proxy for data on wealth. Third, Munich Re's data apparently includes weather and non-weather events (e.g., see figure "d" on page 81, which refers to earthquake damages).

But let's assume that all of these issues raised above can be overcome and in the end there remains a 2 to 1 ratio. The fact is that the large decadal variability in normalized losses makes it quite dodgy to assert a trend between two different ten-year periods over a period of 30 years. Let me illustrate this with an example from our database of normalized hurricane losses. If we adjust the hurricane loss data to 2004 values and then compare decades we see some interesting things. First the ratio of the 1990s:1970s is quite similar to the Munich Re analysis, 2.1 ($91B/$43B). But if we look at other decadal comparisons, the picture looks quite different, 1990s:1940s = 1.0 ($91B/$90B) and 1990s:1920s = 0.6 ($91B/$154B). Bottom line: The Munich Re analysis tells us nothing about attribution.

The Munich Re analysis may prove correct in the end from the standpoint of disasters in the 1970s compared to the 1990s. But all that it would allows us to say is that the 1990s had more costly disasters than the 1970s, and provides absolutely no basis for attribution of the causes of the differences. At a minimum analyses such as Minuch Re's should be submitted for peer review in the scientific literature to allow for an open discussion of data and methods.

Back to the papers cited by Mills:

Association of British Insurers, 2004. Mills cites this report as follows, "The Association of British Insurers states that changes in weather could already be driving UK property losses up 2 to 4% per year (7) owing to increasing extreme weather events."

The executive summary of the AIb report does claim, "Weather risks are already increasing by 2 - 4 % per year on the household and property accounts due to changing weather." But if you read down just a bit further (on p. 8) the executive summary says something a little different "On reasonable projections of extreme events, the pure risk rate for weather catastrophes is already rising at an unseen rate of 2 - 4 % per year." It has now raised the issue of projections. And if you take a look at the Technical Annex to the report, you find something different still, "Thus on the basis of the Foresight Programme view of future flood risk, realistically the risk of flood damage is projected to increase by between 2.1% and 3.9% per annum, or a range of two to four percent per year."

There are two important points here. First, the 2%-4% per year increase in damages is a projection made out over the next 80 years. Second, we discussed the Foresight project quite favorable here last year. The Foresight project was notable because it considered both climate and societal factors in its projections. The 2%-4% number is not based on climate factors alone. Mills' statement is thus incorrect in two ways - the increase in damage is projected, not observed, and it is the consequence of societal and climate factors, not an observed increase in extreme events.

Mills next cites the IPCC WGII, Chapter 8 to justify the claim "According to the latest Intergovernmental Panel on Climate Change (IPCC) assessment, climate change has played a role in the rising costs of natural disasters." If you go to the IPCC you see that the single basis for this claim is the Munich Re 2000 report discussed above. This is the third different reference to the same analysis. At best this is sloppy citing. At worst it appears as if there is an attenmpt to portray a broader intellectual base of support for these claims than there actually is.

Lastly in this section, Mills et al. 2002 discuss the relationship of lightning claims and temperature, which makes sense as lightning tends to be associated with thunderstorms and thunderstorms occur in summer not winter. As they state "An additional issue is that peak lightning periods occur in summer, when electricity reliability problems are likely to cause other business interruption losses, as suggested by the illustration." There is no data here relevant to understanding historical trends in disasters (or insurance claims).

So here is my tally:

3 sources are each traced back to a single non-peer reviewed source, Munich Re 2000, that raises some serious questions of methods and interpretation.

4 papers are cited but are not at all relevant to the issue of disaster losses or attribution.

1 paper (AIB) is mis-cited, which is easy to see if you actually look beyond the first page of its executive summary. (Ironically, the Foresight report which forms the basis for the AIB claims actually makes a good case for the overwhelming dominance of societal factors in future flood losses in the UK.)

1 paper is cited accurately, Easterling et al., but in my opinion this paper plays fast and lose with language to allow a mis-interpretation of its results.

1 paper Kunkel et al. is cited accurately, though I might take issue with the spin, it is probably within the bounds of appropriateness.

Of 10 citations, 9 are highly questionable. And this is Science magazine.

The bottom line is that the issue of attribution of trends in disaster losses rests on the thin reed of a single citation in the IPCC WG2 Chapter 8 to a 2000 Munich Re report that seems to be cited over and over again. Through citing this report several times via different secondary sources, the citing of multiple irrelevant sources and the careful parsing of two papers, Mills comes to the conclusion that climate change is responsible for some part of the observed trend in losses. There is a much, much larger literature on this subject that Mills does not cite.

These are not characteristics that one expects to see in a paper in Science, arguably one of the two most influential publications on science in the world. I have submitted a brief comment in the form of a letter to Science on this paper referencing some of this broader literature. Let's see what happens.

In the end, scientific research may yet prove that anthropogenic climate change plays a observable role in disaster losses. But today, August 22, 2005, shoddy science, bad peer review and a failure of the science community to demand high standards is not the best recipe for helping science to contribute effectively to policy.

Posted on August 22, 2005 09:21 AM


"I accept the IPCC WGI consensus position on climate change..."

What consensus are you referring to?

The most important portions of the IPCC Third Assessment Report, bar none, are the "projections" of what will happen if governments do not act. Do you agree with those projections?

Posted by: Mark Bahner at August 22, 2005 10:45 AM

Oh Mark... how dull of you. RP writes a long interesting post taking a careful analysis of disaster costs and sources, and you keep picking at the same old scab.

Roger: I too have a question: my impression is that most people read the WG I reports, they were written by the best people, and they have proved pretty robust. By contrast, I'm not very familiar with the WG II or III reports and I have the impression that fewer people have read them and that they are less good. What would you say?

Posted by: William Connolley at August 22, 2005 02:25 PM

Hi WIlliam-

Thanks for the comment and help keeping this thread on subject. I am actually a bit surprised that there is so little reaction to this post. Something I'll have to mull on a bit.

As far as the IPCC working groups, I do think that you are on to something. Though I do think it is more complicted than just the quality of the reports. I have written elsewhere that WGs II and III use different definitions of climate change than I and thus are framed much more in an advocacy manner. I was an expert reviewer for Ch 8 of WGII for the TAR and was not too pleased with the content. Perhaps I'll post my review of that chapter here. I wonder how AR4 will handle this issue. I've not been asked to review the relevant chapter.

Policy maker and media discussion of the IPCC almost exclusively focuses on the work of WGI. The public (and highly political) debates over the hockey stick and the surface/satellite temperature record are all located in WGI issues. There is the PPP/MER debate from WG III that is a notable exception.

Posted by: Roger Pielke Jr. at August 23, 2005 06:45 AM

I happen to agree with this. From what I've read, climate scientists are always wary to connect natural disasters to GW (at least, as presented in the media). Usually when I go on a tirade over GW it is when someone claims the science is unsettled on whether anthropogenic warming is occurring, since I'm rather convince that is not the case. When it comes to whether we should act, it enters the realm of politics (which, I believe, is the distinction you try to make).

Though, your parallel to the Hockey Stick suggests there are interest groups/think tanks behind this claim and are faking research to support it. Has this been the case? Or is this a result of sloppy reporting?

What is confusing from my admittedly layman position is that scientists, as presented in the media, seem to say climate change would effect weather, but that attributing any weather to GW is unsound. So, is climate change not widely believed to effect weather, or is this like saying a warming climate doesn't mean an unusually hot summer is a result of global warming?

Posted by: Dylan Otto Krider at August 23, 2005 08:22 AM

Dylan- Thanks for these comments. I think von Storch's original anaology (and mine in borrowing adopting it here) is simply a reference to the shape of the curve. However, I do think that there is some irony here -- what is more relevant to decision making, the global average temperature 500 years ago or the relationship of extreme events with actual damage in recent years and decades? Seems like a no-brainer to me, but paradoxically the attention is exactly opposite the significance. This seems to me to be a common characteristic of scientized debates. There are folks in interest groups and the scientific community who flaunt science in the area of disasters and climate change and they are rarely, if ever, called to task on their misuse of science in the same manner that, for example, the climate science community goes to the mat over satellite temperature trends measured to the thousandth of a degree. This selective attention to ensuring scientific accuracy surely says something about a bias in the community's (both scientific and interest group) attention and willingness to get the science right in different contexts.

Posted by: Roger Pielke Jr. at August 23, 2005 09:19 AM

If conservative think tanks were more grounded in reality, perhaps they'd be attacking this science rather than satellites and the Hockey Stick. They certainly have the money and the megaphone. At least here they'd have a point.

Posted by: Dylan Otto Krider at August 23, 2005 09:57 AM

Dylan- Thanks. But it seems to me that it would be in the interests of both conservative think tanks and green advocacy groups, not to mention the scientific community, to make sure that all climate science is solid -- even that focused on climate impacts (!). I am sure that the selective upholding of science standards within the climate community is one factor that contributes to its continued politicization.

Posted by: Roger Pielke Jr. at August 23, 2005 10:22 AM

William Connolley writes, “Oh Mark... how dull of you. RP writes a long interesting post taking a careful analysis of disaster costs and sources, and you keep picking at the same old scab.”

Oh William…I suggest you brush up on your analogies! A “scab” is a wound that has partially healed. The IPCC (or the “climate change community” for that matter) has never acknowledged that the “projections” in the IPCC Third Assessment Report are pseudoscientific rubbish. Ergo, the “wound” has not healed. In fact, the “science” of the IPCC (and the “climate change community”) actually grows ever more laughable, as Roger Pielke’s excellent piece amply demonstrates.

P.S. By the way, you have claimed to be able to discern the “IPCC consensus” from the IPCC TAR. (I believe your exact words were, “Mark - you really are completely clueless. We already know what the IPCC authors think... because they've written this thing called...yes, thats right... oh don't remind me, its on the tip of my tongue... yess... "The IPCC report"."

Given your position on the matter, you should have no trouble categorizing the 8 assertions listed in my blog as “true” or “false”...and you should also be able to easily answer the final “short answer” question:

Posted by: Mark Bahner at August 23, 2005 10:34 AM

Roger Pielke writes, "Thanks for the comment and help keeping this thread on subject."

Actually, my comment was very much "on subject." You made an extremely solid case for the position that, to date, claims that anthropogenic climate change has not discernably affected disaster losses.

So, if we accept your position, the next question becomes, "What about the future?"

To answer that question, we'd have to have some ideas of the changes expected in the future. I expect you'd agree that there would be no noticeable influence if the temperature were to go back down (for example)?

You also state, "I accept the IPCC WGI consensus position on climate change."

But you don't identify what (you think) that "consensus position" is. What do you think that "consensus position" is...especially regarding future temperatures?

Posted by: Mark Bahner at August 23, 2005 10:49 AM

Oops...typo trying to get finished by the end of lunch. I intended to write,

"Actually, my comment was very much 'on subject.' You made an extremely solid case for the position that, to date, anthropogenic climate change has not discernably affected disaster losses."

Posted by: Mark Bahner at August 23, 2005 10:52 AM

You do seem to point to some pretty sloppy science here, no doubt about it. There's no excuse for making an asssertion based solely on a non-peer reviewed paper.

I do wonder if the focus of climate scientists on Satellite data and Hockey Sticks is a reaction to the attacks by conservative think tanks. The bad science you show above is in some ways more disturbing, since it may point to a bias in the scientific community itself, but it is not think tank driven. It is occuring in peer reviewed journals where people like you can submit papers for peer review in contradiction of those claims. It is the scientific process at work.

In other words, the left is not getting involved in the scientific community, but waiting for consensus to emerge for the most part, which is the role you suggest they should play. They are doing a better job of confining their critiques to what we know, whereas conservative think tanks are trying to influence scientific conclusions. Again, these are generalizations, and some of it might simply have to do with the conservative lock on power. The left has in the past, and may again in the future, do the same to the same degree.

You expressed some surprise that this post didn't spark more debate, but I think that is a result of the very dynamic I'm talking about. I certainly come off as a partisan zealot, but I'm a zealot for the scientific process. If science says climate change doesn't cause hurricanes, I'm willing to accept that, and I'm willing to stand back and let the process work until a consensus emerges. I have no particular ideological need for hurricanes to be caused by GW, nor do I have any particular need to believe the Earth is warming. What I do want is a functioning scientific system that can determine these things, and for politics as much as possible to be based on different ideas of how to deal with these facts as they emerge rather than making up our own facts to suit us.

Posted by: Dylan Otto Krider at August 23, 2005 11:40 AM

Dylan- Thanks for these additional comments. I may not be understanding correctly the distinction that you are making with conservative think tanks. Here are some (of many) examples of groups that are in my view misusing information on climate change and disasters:

Posted by: Roger Pielke Jr. at August 23, 2005 02:36 PM

The Red Cross connects GW to earthquakes? Wow.

Worldwatch states that it is impossible to connect individual weather occurrences to GW. This gets back to my previous question about whether you're saying GW does not predict chaotic weather, or is like claiming a hot summer is evidence of an overall warming trend. Sounds like your issue is the former.

Glancing at the third one, it consists of links in to articles in the BBC, AP and the Guardian, not their own research. Do you object to the articles by these mainstream press outlets, or do you object to something else on the site?

Posted by: Dylan Otto Krider at August 23, 2005 03:22 PM


Thanks. Just a few more comments on this.

Worldwatch is trying to have it both ways by saying that global warming can't be connected to any one weather event (true enough) but then descibing a whole series of damaging weather events on a page about global climate change.

Ross Gelbspan, principal of the other site, is pretty well known for asserting links between weather diasters and climate change. Greenpeace has done that often as well.

The point here is that the misuse of climate science seems to be an issue across the political spectrum and across different sorts of organizations.

Posted by: Roger Pielke Jr. at August 23, 2005 03:36 PM

Yeah, I'm not going to go tit for tat on this because I'll probably lose, and I'll agree with that.

Posted by: Dylan Otto Krider at August 23, 2005 04:04 PM


Greenpeace in Victoria, Australia recently broke into a coal fired power station to highlight the fact that it was contributing to global warming. Unfortunately for them the day they did it there was snowfall over much of the low lying country side around it an event which had not been seen for decades. Yet they still claimed that this was the result of climate change (note they did not say AGW). So the conclusion is that global warming causes snow??? Incidently few days later Victoria had temperatures in the low 20c's this is not unusual but the weather men still felt they needed to point out that it was not unusual and shouln't be seen as being linked to global warming. So we had some snowy days and some warmer days and pretty much an average winter.

Posted by: Ross McNaughton at August 23, 2005 05:34 PM

Yeah, true. As I said above, a warm summer doesn't mean the world is warming. And like I said, I'm on shaky ground here, so I'll just concede the point.

All I was getting at is I go heatisonline which provides almost nothing but links to mainstream newssites, and a book with the following description:

"In Boiling Point, Pulitzer Prize-winning journalist Ross Gelbspan argues that, unchecked, climate change will swamp every other issue facing us today. (expected policy hyperbole) Indeed, what began as an initial response of many institutions-denial and delay-has now grown into a crime against humanity. (over-the-top policy hyperbole) Gelbspan's previous book, The Heat Is On, exposed the financing of climate-change skeptics by the oil and coal companies. (true) In Boiling Point, he reveals exactly how the fossil fuel industry is directing the Bush administration's energy and climate policies -payback for helping Bush get elected. (true) Even more surprisingly, Gelbspan points a finger at both the media and environmental activists for unwittingly worsening the crisis. (definitely true) Finally, he offers a concrete plan for averting a full-blown climate catastrophe. (now I'm getting worried) According to Gelbspan, a proper approach to climate change could solve many other problems in our social, political, and economic lives. (okay, that wasn't so bad...) It would dramatically reduce our reliance on oil, and with it our exposure to instability in the Middle East. (Okay, I'm relaxing a little... it's still policy...) It would create millions of jobs and raise living standards in poor countries whose populations are affected by climate-driven disease epidemics and whose borders are overrun by environmental refugees. (Huh? Now you've lost me...)"

And then I go to TechCentralStation and read this:

"CO2 is an aerial fertilizer benefiting the biosphere, particularly in areas of limited rainfall."

And then I read about their studies that wetlands cause pollution, or about the fake Oregon Petition which falsely claimed to have been signed by thousands of scientists supporting a paper on letterhead to make it look like peer reviewed research, and then I see yet another study funded by the American Petroleum Institute meant to show Benzene is safe.

Which is worse? Both distort facts to push their cause. But I guess what concerns me the most is this producing of fake research which the right is trying to put on an equal footing with peer reviewed research to provide "balance" to science they don't like, and the creation of their own "scientific journals" that specialize in publishing ideological science to bamboozle the media.

Perhaps the left is also funding fake research and creating their own journals (I know there are some journals that publish research on ESP and UFOs). If you know of any, send me the links. I'd be interested in looking them over.

Posted by: Dylan Otto Krider at August 23, 2005 06:06 PM


Minor quibble: The fossil fuel lobby's think tank and astroturf campaign has gone to great lengths to portray the environmental movement as "left." Apparently they've succeeded, at least with you. It's not even faintly true, by the way.

My bare-bones analysis: The *environmental* movement did not, after all, invent global warming or the IPCC, and hasn't needed to resort to fake science simply because we have been willing to go with the research and conclusions that the scientific community provided. Of course, the greedy/short-sighted world-view of the fossil fools naturally led them to conclude that the AGW "consensus" must be some kind of left-wing conspiracy since it leads to conclusions that constrain the expression of that world-view. The fact that these constraints are broadly consistent with positions environmentalists were already advocating (e.g., clean air) made it seem even more like a conspiracy.

Q: How many climate scientists are members of environmental organizations? A: Way more than 57.

Posted by: Steve Bloom at August 24, 2005 03:12 PM

"The fossil fuel lobby's think tank and astroturf campaign has gone to great lengths to portray the environmental movement as "left." Apparently they've succeeded, at least with you. It's not even faintly true, by the way."

Heh, heh, heh! Good one!

What percentage of the combined U.S. membership of the Sierra Club, Environmental Defense, Greenpeace are Democrats or Greens, vs Republicans or Libertarians? I would be shocked if it's less than 80 percent Democrats and Greens, and I wouldn't be at all surprised if the combined U.S. membership was more than 90 percent Democrats and Greens.

"Of course, the greedy/short-sighted world-view of the fossil fools naturally led them to conclude that the AGW "consensus" must be some kind of left-wing conspiracy..."

What "consensus" are you referring to?

Posted by: Mark Bahner at August 25, 2005 10:27 AM

Creating reality again, eh, Mark? Karl would be proud of you.

FYI, the Sierra Club up until the late '60s was majority Republican. That's not true now, of course, but there are a lot more Republicans than you might imagine. Since the Club is officially non-partisan, a party affiliation statistic is not collected, but I can assure you based on numbers that I've seen from the SF Bay Area (a known hotbed of Dems and Greens) that there are more than 10% Republicans here, to say nothing of a fair number of decline to states. Remember that the Club has a huge membership compared to those other organizations, and that of the active membership many more are involved in "activities" (hiking, e.g.) than in politics or activism. I'm sure you're right that ED and Greenpeace are a different story, though. That said, of course your conflation of Democrats with "left" is absurd, although it's fair to say of the Greens (a very small minority in the Club at least).

Regarding the consensus, that would be the oft-cited scientific consensus. But you knew that.

Posted by: Steve Bloom at August 25, 2005 12:02 PM

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