Rebuttal to Åström et al. Attributing mortality from extreme temperatures to climate change in Stockholm, Sweden., published in Nature Climate Change by Paul C. “Chip” Knappenberger, Patrick J. Michaels, and Anthony Watts
Last fall, the press pounced on the results of a new study that found that global climate change was leading to an increasing frequency of heat waves and resulting in greater heat-related mortality. Finally a scientific study showing that global warming is killing us after all! See all you climate change optimists have been wrong all along, human-caused global warming is a threat to our health and welfare.
Not so fast.
Upon closer inspection, it turns out that the authors of that study—which examined heat-related mortality in Stockholm, Sweden—failed to include the impacts of adaptation in their analysis as well as the possibility that some of the temperature rise which has taken place in Stockholm is not from “global” climate change but rather local and regional processes not related to human greenhouse gas emissions.
What the researchers Daniel Oustin Åström and colleagues left out of their original analysis, we (Chip Knappenberger, Pat Michaels, and Anthony Watts) factored in. And when we did so, we arrived at the distinct possibility that global warming led to a reduction in the rate of heat-related mortality in Stockholm.
Our findings have just been published (paywalled) in the scientific journal Nature Climate Change as a Comment on the original Oustin Åström paper (which was published in the same journal).
We were immediately skeptical because the original Oustin Åström results run contrary to a solid body of scientific evidence (including our own) that shows that heat-related mortality and the population’s sensitivity to heat waves was been declining in major cities across America and Europe as people take adaptive measures to protect themselves from the rising heat.
Contrarily, Oudin Åström reported that as a result of an increase in the number of heat waves occurring in Stockholm, more people died from extreme heat during the latter portion of the 20th century than would have had the climate of Stockholm been similar to what it was in the early part of the 20th century—a time during which fewer heat waves were recorded. The implication was that global warming from increasing human greenhouse gas emissions was killing people from increased heat.
But the variability in the climate of Stockholm is a product of much more than human greenhouse gas emissions. Variations in the natural patterns of regional-scale atmospheric circulation, such as the Atlantic Multidecadal Oscillation (AMO), as well as local impacts associated with urbanization and environmental changes in the direct vicinity of the thermometer are reflected in the city’s temperature history, and the original Oudin Åström et al. publication did not take this into account. This effect is potentially significant as Stockholm is one of Europe’s fastest growing cities.
But regardless of the cause, rising temperatures spur adaptation. Expanded use of air conditioning, biophysical changes, behavior modification, and community awareness programs are all examples of actions which take place to make us better protected from the dangers associated with heat waves. Additionally, better medical practices, building practices, etc. have further reduced heat-related stress and mortality over the years.
The net result is that as result of the combination of all the adaptive measures that have taken place over the course of the 20th century in Stockholm, on average people currently die in heat waves at a rate four times less than they did during the beginning of the 20th century. The effect of adaptation overwhelms the effect of an increase in the number of heat waves.
In fact, it is not a stretch to say that much of the adaptation has likely occurred because of an increased frequency of heat waves. As heat waves become more common, the better adapted to them the population becomes.
Our analysis highlights one of the often overlooked intricacies of the human response to climate change—the fact that the response to a changing climate can actually improve public health and welfare.
Which, by the way, is a completely different view than the one taken by the current Administration.
References:
Knappenberger, P., Michaels, P., and A. Watts, 2014. Adaptation to extreme heat in Stockholm County, Sweden. Nature Climate Change, 4, 302-303.
Oudin Åström, D., Forsberg, B., Ebi, K. L. & Rocklöv, J., 2013. Attributing mortality from extreme temperatures to climate change in Stockholm, Sweden. Nature Climate Change, 3, 1050–1054.
The paper:
Adaptation to extreme heat in Stockholm County, Sweden
Online at: http://www.nature.com/nclimate/journal/v4/n5/full/nclimate2201.html
============================================================
Further detail by Anthony:
It should be noted that Nature Climate Change, which tends to be a fast track journal, took months to publish our correspondence, going through a longer than normal review process for such a short correspondence, and only did so along with a reply from Åström et al. Despite this uphill slog, we persevered.
Personally, I think the response from Åström et al. is ludicrous, especially this part:
“Our data indicate that there is no adaptation to heat extremes on a decadal basis or to the number of heat extremes occurring each year. “
Basically what they are saying is the people of Stockholm are too stupid to use an air conditioner or electric fan when it gets hot, and are incapable of any adaptation.
The other part of their response:
Our method of comparing the climate during two 30-year periods is valid for any two periods.
Well no, not really, and it is this flaw in their method that was a central point of our paper.
Variations in the natural patterns of regional-scale atmospheric circulation, such as the Atlantic multidecadal oscillation (AMO) as well as local impacts associated with urbanization and environmental changes in the direct vicinity of the thermometer are reflected in the city of Stockholm temperature history, and the original Åström et al. publication did not take this into account. By not looking at these factors, and by just taking the Stockholm temperature data at face value, assuming all of the heat extremes in it were “climate change” induced instead of being partially influenced by other effects, including the AMO and the city itself, allowed Åström et al. to become victims of their own confirmation bias.
For example, look at the GISTEMP record from Stockholm (which ends before 2000, not my fault). Note the 1900-1929 period.
Åström et al. compared two periods of Stockholm temperature data: 1900–1929 and 1980–2009, and used them as the basis for their entire paper. Here is their method from the abstract posted on the NIH website:
Methods: We collected daily temperature data for the period 1900-2009 and daily mortality data for the period 1980–2009 in Stockholm, Sweden. The relationship between extreme temperatures and all-cause mortality was investigated through time series modelling, adjusting for time trends. Attribution of mortality to climate change was calculated using the relative risks and baseline mortality during 1980-2009 and the number of excess extreme temperature events occurring in the last 30 years as compared to our baseline period 1900-1929. Results: Mortality from heat extremes doubled due to warming associated with climate change. The number of deaths attributable to climate change over the last 30 years due to excess heat extremes in Stockholm was estimated to be 323 (95% CI: 184, 465) compared with a reduction of 82 (95% CI: 43, 122) lives saved due to fewer cold extremes.
Only one problem, a big one, note that right after 1929 there was a big shift in the AMO data – what happens to the AMO in 1930 is essentially a “sea change”.
After 1930, the AMO was positive (warm phase) for over 30 years, went negative (cold phase) again around 1963-64, and stayed negative until a big uptick around 1998.
The AMO was primarily in its cold phase during the 1900–1929 period, and primarily in its warm phase during the 1980–2009 period — a difference likely to be responsible for some portion of the increase in extreme-heat events identified by Åström et al. and inappropriately attributed to global climate change. See Sutton and Dong 2012 for an explanation as to why the AMO affects the temperature record of Europe.
Then there were the changes/growth in the city itself, some movements and encroachments on the Stockholm observatory station, plus the fact that the mortality numbers they cited didn’t make sense when compared to other studies of trends in heat-related mortality across the United States and Europe which have reported declines in both total mortality and the sensitivity of urban populations to extreme heat,despite an increasing frequency of extreme-heat events.
Despite the long review, to the credit of Nature Climate Change, they recognized that we had a valid argument that mostly nullified the Åström et al. paper. Otherwise we’d never have gotten this published. Unfortunately, we can’t counter all the media hype from the original publication, but I hope readers will cite our rebuttal when appropriate.
Knappenberger_Michaels_Watts_Correspondence_original (PDF)
– Anthony
Huge svalgard flare narrowly misses chip of Earth. Sunspots still going out of the visible spectrum except for large, sparse, and hemispherically asymmetrical ones.
===============
Chip Knappenberger says:
May 1, 2014 at 9:27 am
I am sorry that they didn’t meet your expectations.
I am sorry about that too. I had expected more. 🙁
Anthony Watts says:
May 1, 2014 at 9:56 am
While I very much think open review would be a good thing we agreed to play in their sandbox by their rules and to violate them now would do nothing other than reflect badly on us.
Their rules do not prohibit an informal, paraphrased general description of what the objections and the responses were, so you are just hiding behind them rules.
While the review process was overly long it was not overly contentious and there is no “smoking gun” in the review to expose.
this is not your conclusion to make, it is for the readers to decide, but now you have cut your readers off, and that already reflects badly on you. But, as I said, I admit defeat, but allow me to stand up for my principles.
Leif I have no problem publishing paraphrased comments but that is still for Chip to decide
Anthony,
I already did this: http://wattsupwiththat.com/2014/04/30/new-skeptic-publication-in-nature-climate-change-rebuts-strm-et-al-claims-of-increased-deaths-due-to-heat-waves/#comment-1626275
This seems plenty sufficient.
-Chip
For those wondering why the original Astrom et al. results that climate change was leading to an increase in heat-related mortality initially caught our attention, see this new paper in Environmental Health Perspectives (http://ehp.niehs.nih.gov/1307392/) that includes:
“This study provides strong evidence that acute (e.g., same-day) heat-related mortality risk has declined over time in the US, even in more recent years. This evidence complements findings from US studies using earlier data from the 1960s through mid-1990s on community-specific mortality rates (Davis et al. 2003a; Davis et al. 2003b), as well as European studies that found temporal declines in heat-related mortality risk (Carson et al. 2006; Donaldson et al. 2003; Kysely and Plavcova 2011; Schifano et al. 2012), and supports the hypothesis that the population is continually adapting to heat.”
(FWIW, I was a co-author on the two Davis et al. studies which were the first to look a trends in heat-related mortality instead of temporal averages).
-Chip
Chip Knappenberger says:
May 1, 2014 at 10:48 am
supports the hypothesis that the population is continually adapting to heat
How does that square with the 2003 Eoropean heatwave?
http://en.wikipedia.org/wiki/2003_European_heat_wave
Leif,
From Fouiltte et al. 2006 (http://ije.oxfordjournals.org/content/37/2/309.full and cited in our Nature Climate Change piece):
“Conclusions The excess mortality during the 2006 heat wave, which was markedly lower than that predicted by the model, may be interpreted as a decrease in the population’s vulnerability to heat, together with, since 2003, increased awareness of the risk related to extreme temperatures, preventive measures and the set-up of the warning system.”
-Chip
Heh, guilt from ’03 engendered more caring in ’06. Manifold and mysterious are the ways adaptation manifests.
=================
Chip Knappenberger says:
May 1, 2014 at 11:17 am
“Conclusions The excess mortality during the 2006 heat wave, which was markedly lower than that predicted by the model, may be interpreted as a decrease in the population’s vulnerability to heat, together with, since 2003, increased awareness of the risk related to extreme temperatures, preventive measures and the set-up of the warning system.”
Another example of the half-truths around this subject. Taken at face value it would say that your claim of a dramatic decrease shown by your analysis of the Stockholm data 1980-2009 all occurred in the six years since 2003. Could you direct me to a link showing us the warning system that the Stockholmers benefited from since 2003.
Chip Knappenberger says:
May 1, 2014 at 10:42 am
Anthony, I already did this
As I pointed out upstream, that was not informative and sufficient. Your readers [e.g. me] are the judge of that, not you. And this reader is not satisfied with your performance.
Leif,
Do you have a specific question that you’d like me to address that I haven’t already? If so, please ask it (I can’t guarantee that you’ll be satisfied by the answer, but I’ll try, just as I have been doing all along).
It would be nice to reach closure on this.
-Chip
Chip Knappenberger says:
May 1, 2014 at 12:48 pm
Do you have a specific question that you’d like me to address that I haven’t already?
Since you have not been specific in your report on the objections and your responses it is somewhat hard to put the burden on me. Now, I could play reviewer of your paper http://www.leif.org/EOS/ncclimate2201-Stockholm-Chip.pdf and then see what questions I would ask, as we obviously are not going to get anything more from you. Give me a moment to do this.
lsvalgaard says:
May 1, 2014 at 12:56 pm
Now, I could play reviewer of your paper
My review would start out like this:
[Confidential 🙂 NOT]
Review of ‘Adaptation to extreme heat in Stockholm County, Sweden’:
Your lead-in line: “Oudin Åström et al. argue that global climate change has doubled the incidence of heat-related mortality in Stockholm County, Sweden” is misleading because they do not claim that *global* climate change is responsible for the climate change in Stockholm. Climate changes all the time, also in Stockholm and, clearly, to assess the impact of climate change in Stockholm one must compare with the climate observed in Stockholm [only]. Any other reference to what happened elsewhere is not relevant. I suggest you change the lead-in sentence to “Oudin Åström et al. argue that the local climate change observed at Stockholm has doubled…”
Further in the same paragraph you claim that “Such findings indicate that adaptation has more than kept pace with climate change”. One of the key events in this field is the heat wave in France [and elsewhere] in 2003 where it was concluded that “most people did not know how to react to very high temperatures”. You lack needed discussion of this clear contradiction of your claim. Has much changed in the six years until 2009 [the end year of Åström et al.’s paper]? and where is the documentation of that? apart from the fact that six years hardly is sufficient to build credible statistics upon.
In paragraph three you say “They identify 220 extreme-heat days from 1900–1929 and conclude that *large-scale* climate change was responsible for the additional 158 occurrences…” but the clause ‘large-scale’ occurs nowhere in the Åström et al. paper and sounds like your [additional, and I believe, from the evidence, unfounded] opinion not based on fact. Again, replace with ‘climate change in Stockholm County’ in order to not mislead your readers.
Etc, etc.
—–
needless to say I could go on and on, but you may get my drift before I waste more of yours and my time on this.
jeez Leif. what is your problem? I don’t understand how non access to reviewer comments has turned into such a pssing match.
Anthony Watts says:
May 1, 2014 at 2:08 pm
jeez Leif. what is your problem? I don’t understand how non access to reviewer comments has turned into such a pissing match.
It takes two to have a match, so you may also ask what is the problem of the other pisser(s).
My problem is simple: in order to assess if the paper has been properly peer-reviewed it is necessary to see the reviews AND your responses or at least some paraphrased version if you dare not show the real thing. Especially in this field of hostile opposing views. We have Astrom’s paper and we have yours. Both peer-reviewed. Which one to believe? If you are among the faithful of either stripe you believe what the party line compels you to. If you are a skeptic you want to assess the matter on your own [assuming that you have the scientific training to attempt to do so]. Your attitude prevents me [and other readers] to do so and thus simply lead to dismissal of the whole thing, which is sad. Now it is true that I don’t have access to the reviews of Astrom et al.. That may make we lean more towards the paper with a known review, but in the present situation not even that is possible.
Leif, there’s no “attitude” here on my part. I said I’m fine with reviewing paraphrased comments, and it was up to Chip as lead author to make the decision. I won’t burn my bridges with NCC by violating the rules I agreed to just to satisfy your curiosity.
You are behaving in a way that is not constructive, IMHO.
I’m about to board a plane and will be offline until tomorrow morning, though may have option during layover to check commensts
Leif,
Fair points. My responses are cut into your comments below.
-Chip
[Confidential 🙂 NOT]
Review of ‘Adaptation to extreme heat in Stockholm County, Sweden’:
Your lead-in line: “Oudin Åström et al. argue that global climate change has doubled the incidence of heat-related mortality in Stockholm County, Sweden” is misleading because they do not claim that *global* climate change is responsible for the climate change in Stockholm. Climate changes all the time, also in Stockholm and, clearly, to assess the impact of climate change in Stockholm one must compare with the climate observed in Stockholm [only]. Any other reference to what happened elsewhere is not relevant. I suggest you change the lead-in sentence to “Oudin Åström et al. argue that the local climate change observed at Stockholm has doubled…”
RESPONSE: The term “climate change” is introduced by Oustid Astrom et al. in the opening paragraph of their paper. The references cited throughout that paragraph regard global-scale climate change and include a tie-in to anthropogenic causes (primarily well-mixed greenhouse gas emissions which are global by their nature). Further, a primary justification for their analysis is found in the lead sentence of their paragraph 6 which is “A key policy-relevant question is the extent to which changes in climate-sensitive morbidity and mortality can be attributed to historic climate change [ref 19].” Reference 19 is to the IPCC Fourth Assessment Report—a report largely focusing on anthropogenic impacts on the earth’s climate for which the cause is global in nature. Further, the press release issued by Umea University to publicize the findings by Oustid Astrom (http://www.medfak.umu.se/english/about-the-faculty/news/newsdetailpage/climate-change-increased-the-number-of-deaths.cid223558) link “global warming” to increases in “the frequency and intensity of heat waves.” So while Oustid Astrom et al may not explicitly use the term “global climate change” the association between “climate change” and “global climate change” is strong in their paper and in their public comments.” So we feel the term “global climate change” is a fair description of those associations. We leave that phrase unchanged.
Further in the same paragraph you claim that “Such findings indicate that adaptation has more than kept pace with climate change”. One of the key events in this field is the heat wave in France [and elsewhere] in 2003 where it was concluded that “most people did not know how to react to very high temperatures”. You lack needed discussion of this clear contradiction of your claim. Has much changed in the six years until 2009 [the end year of Åström et al.’s paper]? and where is the documentation of that? apart from the fact that six years hardly is sufficient to build credible statistics upon.
RESPONSE: As you point out, six years is hardly sufficient time to build credible statistics upon. A single event, like the heat wave of 2003, is even less so. The citations we provided (which were necessarily limited in number by Nature’s restrictions on Correspondence) examine trends in heat-related mortality over several decades. They all find that despite a warming climate, the population’s sensitivity to heat waves (as measured by mortality rates) is declining. (for other references see the recent publication by Bobb et al. and citation therein, http://ehp.niehs.nih.gov/1307392/). For references which show that adaptive measures to reduce mortality during heat waves can occur over the very short term (a few years), see Palecki et al and Fouillet et al which examined the effects of heat waves which occurred is rapid succession from the deadly 1995 heat wave in the U.S. Midwest and the 2003 heat wave across Europe, respectively (citations 10 and 11 in our Correspondence).
In paragraph three you say “They identify 220 extreme-heat days from 1900–1929 and conclude that *large-scale* climate change was responsible for the additional 158 occurrences…” but the clause ‘large-scale’ occurs nowhere in the Åström et al. paper and sounds like your [additional, and I believe, from the evidence, unfounded] opinion not based on fact. Again, replace with ‘climate change in Stockholm County’ in order to not mislead your readers.
RESPONSE: See our Response to your first comment.
Etc, etc.
RESPONSE: Etc., etc.
Anthony Watts says:
May 1, 2014 at 2:27 pm
Leif, there’s no “attitude” here on my part. I said I’m fine with reviewing paraphrased comments, and it was up to Chip as lead author to make the decision. I won’t burn my bridges with NCC by violating the rules I agreed to just to satisfy your curiosity.
Then the blame will fall on Chip. But I believe that it is not just my curiosity that needs to be satisfied. Other commenters have agreed that they have the same view. And in any event, I don’t need to lose sleep over this. The solution is simple: dismiss your paper. Of course, you may not care and I can live with that. Most people don’t care what I say, so what is one more?
You may ask: why you? why don’t I demand this of everybody? Because I’m versed enough in most other things that catch my interest to not need any further expertise. On the subject of your paper I’m less sure and I was hoping that the editors of NCC would have found experts that could, at least, raise issues that needed to be addressed [and that I might not be able to see], hence the interest in what the reviewers would have to say, if only in meaning fully paraphrased outline. But, alas, no joy.
Now, Chip is a slick operator, perhaps pissing harder than I, since I have admitted defeat. The last few comments were more by way of clarification than for any hope of turning the yellow tide.
Chip Knappenberger says:
May 1, 2014 at 2:31 pm
Fair points. My responses are cut into your comments below.
It is amazing that things have to be wrung out of you. Now were any of my comments also in the reviewer’s secret, confidential reports?
If you answer that, then I have a way of slowly, painstakingly to find out what those reviews were. You see, I’m a bit of an expert on cryptography and decoding of secrets and some techniques from that field are applicable here. There is, of course, a much easier way: you just tell me up front.
Chip Knappenberger says:
May 1, 2014 at 2:31 pm
So we feel the term “global climate change” is a fair description of those associations. We leave that phrase unchanged.
It is not about what you ‘feel’, but about what the paper actually says. Clearly, the climate in Stockholm is what is important for the study, not the climate in Timbuktu. If you would deny that fact and insist that you would not change the lead-in and thus give your paper a slant the Astrom paper does not have [as I read it], then that alone would be reason enough to reject your paper.
Leif,
I don’t have a confidentiality agreement in place with you. So its is easier to wring things out of me :^) But we have beaten that horse pretty much to death. You know where I stand, if you want the last word, go ahead.
As to the term global climate change, we are refering to responses from a common global forcing. Yes the response is different in Stockholm than in Timbuktu. But the initial impetus for the change was the same. It is pretty hard to make an argument that Oustid Astrom et al did not have a global scale forcing response in mind when they interpreted there results.
-Chip
Chip Knappenberger says:
May 1, 2014 at 4:18 pm
As to the term global climate change, we are refering to responses from a common global forcing. Yes the response is different in Stockholm than in Timbuktu. But the initial impetus for the change was the same. It is pretty hard to make an argument that Oustid Astrom et al did not have a global scale forcing response in mind when they interpreted there results.
I don’t need the last word, but only want to express my sadness about your decision, having reached the point of no scientific return. To me, it is obvious that to study things in Stockholm, only Stockholm matters, but then your paper was more of a political than scientific statement anyway, as also evidenced in the very title of this post, and discussing politics or politically flavored issues is not really my cup of tea. We can let it rest there.
Please, please, no blood on the white togas.
==========
Oh dear, I do hope the double blind review will protect the Journal editor from being sacked for allowing the truth to be spoken. It’s a rather grievous offense.
I just spotted this passage in the original Åström paper (p. 3): “The negative effects of heat in the Stockholm region are apparent during a short summer season and the adaptive measures taken in, for instance, the warmer regions of the United States with an increased use of air conditioning, are not used to the same extent in Sweden. There is very low awareness of the negative health effects of heat in Sweden. Future changes in the frequency and intensity of heat waves might be of a magnitude large enough to overwhelm the ability of individuals and communities to adapt.” Ridiculous. The passage implies that even if, summer after summer, Swedes are dropping like flies from the heat, their “awareness of the negative health effects of heat” will remain “very low” and they won’t use “adaptive measures,” i.e. “air conditioning. Wittingly or otherwise, the researchers reach an adverse judgment about the intelligence of their compatriots.
I have read all of the exchanges between the two principal ‘players’ of this mini –drama, and have nothing but admirations for the Mr. Chip Knappenberger’s conduct.