20 May 2010

Last Word on Malaria?

[UPDATE: In the BBC the lead author of the Nature study has this to say:

"I'd say what we've shown is that if we can provide people with existing technologies such as drugs and bednets, we have the capacity as a global community to reduce the misery this disease causes. Climate change is, in our view, an unwelcome distraction from the main issues."]

Yesterday Nature published a paper on malaria and climate change which has concluded (from the abstract):
Our findings have two key and often ignored implications with respect to climate change and malaria. First, widespread claims that rising mean temperatures have already led to increases in worldwide malaria morbidity and mortality are largely at odds with observed decreasing global trends in both its endemicity and geographic extent. Second, the proposed future effects of rising temperatures on endemicity are at least one order of magnitude smaller than changes observed since about 1900 and up to two orders of magnitude smaller than those that can be achieved by the effective scale-up of key control measures. Predictions of an intensification of malaria in a warmer world, based on extrapolated empirical relationships or biological mechanisms, must be set against a context of a century of warming that has seen marked global declines in the disease and a substantial weakening of the global correlation between malaria endemicity and climate.
An accompanying Nature News article has this to say:
On the surface, the connection between malaria and climate change is intuitive: higher temperatures are known to boost mosquito populations and the frequency with which they bite. And more mosquito bites mean more malaria.

Yet when epidemiologists Peter Gething and Simon Hay of the Malaria Atlas Project at the University of Oxford, UK, and their colleagues compiled data on the incidence of malaria in 1900 and 2007 (see page 342), they found the opposite: despite rising temperatures during the twentieth century, malaria has lost ground. According to the models the researchers used to tease out the factors affecting the incidence of malaria, the impact of public-health measures such as improved medications, widespread insecticide use and bed nets have overwhelmed the influence of climate change. "Malaria is still a huge problem," says Gething. "But climate change per se is not something that should be central to the discussion. The risks have been overstated."

Some earlier analyses painted a dire picture of a malaria-ridden future, but these models often exclusively evaluated the impact of warmer temperatures without taking other factors into consideration, says Paul Reiter, an entomologist at the Pasteur Institute in Paris. The latest assessment of the Intergovernmental Panel on Climate Change noted these concerns: "Despite the known causal links between climate and malaria transmission dynamics, there is still much uncertainty about the potential impact of climate change on malaria at local and global scales."

The Nature News article ends on a predictable note, quoting a researcher who says:
"This does not diminish the importance of climate change at all."
I agree with this statement of course, because I never thought addressing malaria was a key justification for dealing with climate change in the first place. However the systematic overselling of malaria and climate change in the past requires some attention, and it is not the only context in which these dynamics have occurred -- disasters and climate change provides another obvious example.

Readers from last summer may remember that I took issue with the Global Humanitarian Forum's absurd estimate of more than 300,000 deaths per year due to human-caused climate change, mainly due to diseases and including malaria. The new study underscores my critique.

Hopefully, the new study will mark a new era in the climate debate where it is accepted among the mainstream scientific community to raise challenges to unsupportable claims made to support action, rather than seeing them go unquestioned because of the perceived delicate politics of the climate issue. In this spirit, I see that Andy Revkin, who also discusses the paper, pokes a little fun at one such serial exaggerator.

27 comments:

  1. "On the surface, the connection between malaria and climate change is intuitive: higher temperatures are known to boost mosquito populations and the frequency with which they bite. And more mosquito bites mean more malaria."

    Intuitive or just plain ignorant? Well if you don't know about the huge mosquitos in Alaska or that the biggest malarial outbreak was in Siberia then it's surely the latter.

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  2. I seem to remember Paul Reiter resigned from the IPCC over the fudging/fraud regarding malaria: http://commerce.senate.gov/pdf/reiter-042606.pdf

    He writes:

    "In this brief presentation I restrict my comments to malaria, and emphasise four points:
    1. Malaria is not an exclusively tropical disease
    2. The transmission dynamics of the disease are complex; the interplay of climate, ecology, mosquito biology, mosquito behavior and many other factors defies simplistic analysis.
    3. It is facile to attribute current resurgence of the disease to climate change, or to use models based on temperature to “predict” future prevalence.
    4. Environmental activists use the ‘big talk’ of science to create a simple but false paradigm. Malaria specialists who protest this are generally ignored, or labelled as ‘sceptics’."

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  3. People all too easily forget that in historic times, Malaria was endemic in places as tropical as the Netherlands and the UK. Human action wiped it out.

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  4. "Hopefully, the new study will mark a new era in the climate debate where it is accepted among the mainstream scientific community to raise challenges to unsupportable claims made to support action, rather than seeing them go unquestioned because of the perceived delicate politics of the climate issue. "

    Hear, hear!!!

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  5. Since there has been so many studies on malaria and climate change we can conclude that this new study shows that we have been systematically misled by scientists over the past decade.

    Is that another fudge Roger?

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  6. Envisaging more malaria by 2100 based on expectations of increased temperature, is equivalent to some Victorian researcher predicting 20th/21st century London devastated by cholera, based on projections of increasing urban concentration and the (then) known association between urbanisation and cholera.

    It is in fact, worse, since this Nature study shows that the relationship between malaria and climate has already been shown to be wrong.

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  7. Many catastrophic impact assessments in the climate change debate depend on the notion of 'potential impact' embraced by the IPCC. A 'potential impact' is the impact of climate change 'in the absence of adaptation'. In practice, it is in the absence of adaptation and in the absence of any technological change. ('Residual impact' is impact after adaptation).

    The notion of potential impact is misleading. Since people adapt themselves to their environment, and technology changes rapidly nowadays, both adaptation and technological progress should be built into the projections, i.e. endogenised.

    Evaluating the impact of temperature alone, supposedly 'keeping constant' other relevant factors, is plain wrong, since those other factors will change along with climate. Such univariate model would be like a GCM without any feedback. Well, in fact there are plenty GCMs with little attention paid to (esp. negative) feedbacks.

    In short, potential impact, so defined, is hardly a helpful concept. I hope the next IPCC report uses a better notion of impact.

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  8. Excellent news. It is also a change of policy for the BBC to report that there is something in the world that won't go disasterously wrong due to AGW.

    It's not totally beyond the realms of possibility that a new government may be the reason. Pure speculation on my part, but it will be interesting to watch future developments.

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  9. Malaria, also known as paludism, was originally described and named in Rome, hardly a tropical town though quite hot in summer. The illness was (correctly) attributed to the unsanitary conditions of the swamps around the seven Roman hills, hence 'foul air' (mal aria) and 'paludism' from 'palude'=swamp in Italian. The illness was rampant all over Europe, and was thought to come from the foul air of swamps and other humid places (in fact, those places hosted the mosquitoes).

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  10. "This does not diminish the importance of climate change at all."

    Of course this statement is true, but the malaria issue highlights a reality that likely applies to all aspects of climate change--whatever impact climate change will have now and in the future, though certainly real, will always be a small contributor relative to the effects of normal human progress.

    Disease increases? Small compared with reductions by medical progress.

    Damage increases by hurricanes? Small compared with effects of coastal development.

    Displacement of people by sea-level rise? Small compared with normal human migration and effects of development on coastline.

    Changing patterns of agriculture? Small compared with normal human development trends.

    Increasing pressure on marginal societies? Small compared normal human development trends.

    etc., etc., etc.

    So, no, this does not reduce the importance of climate change one iota. Climate change, though real, will never be particularly important, probably at most a third- or fourth-order concern. And this report on malaria does nothing to change that.

    Roger, do you agree with this assessment? And if not, in what area of human interest do you consider climate change to be a first- or second-order concern (i.e., being the primary or at least secondary reason for action)?

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  11. "Since people adapt themselves to their environment, and technology changes rapidly nowadays, both adaptation and technological progress should be built into the projections, i.e. endogenised."

    Yes, technological and economic progress are essentially ignored in projections the impacts of climate change.

    Hence, one does not find any estimate of the actually number of deaths from malaria in the IPCC assessment reports (e.g., "in 2100, the most likely number of malaria deaths worldwide is 1000"). Instead, there are estimates of the number of people who will be at increased "risk" due to climate changes.

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  12. This is not news.

    Malaria expert Paul Reiter has been saying this for years.
    Look up his articles on Google scholar:

    Global warming and mosquito-borne disease in USA (1996)
    Malaria in England in the Little Ice Age (2000)
    Global warming and malaria: a call for accuracy (2004)

    This 'new' paper only cites one of Reiter's more recent ones.

    Reiter's reward is to be ignored or attacked as a denier.

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  13. I agree with PaulM. Why is this news?

    I really don't get it, can anyone explain why this ends up in Nature when an expert like Paul Reiter has been stating this for years, even decades?

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  14. Roger, a number of your more narky readers have asked whether in your opinion any previous studies which did posit a, presumably meaningful, connection between warming and malaria, are guilty of fudge or fraud.

    I don't want to re-open the arid definitional debate, but there are two points I'd like your opinion on:

    1 'claims that rising temperatures have led to increases in worldwide malaria morbidity and mortality are largely at odds with observed decreasing global trends in both its endemicity and geographic extent.'

    To us laymen this is a statement of the bleedin' obvious, that non-temperature impacts are clearly magnitudes more important - do scientists just not realise that, or is it actually not relevant to them?

    2 If I assume that they do realise that, what is the inventive to produce studies that say temperature is important?

    (I should say I am NOT expert in such studies, for all I know they may well stress the small likely impact of temperature.)


    I understand the fury that people feel being deluged with what looks, smells, and walks like alarmism.

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  15. -14-Roddy

    Please follow the links above to what I had to say about the GHF "study" -- I called it a "methodological embarrassment". But not a fraud, and not scientific misconduct.

    On disasters and climate change I called it "systematic misrepresentation" but not fraud.

    This paper by Dan Sarewitz may help to explain my views:

    http://www.cspo.org/products/articles/excess.objectivity.html

    Maybe worth a blog post.

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  16. You are correct, of course: this news that malaria is not impacted by climate change does not change its importance at all. One cannot reduce zero. something that has never had any importance except as a social mania cannot become less important in terms of reality.
    But one can hope that the social mania of catastrophic AGW will continue to decline in importance and that rational decision making will take its place.
    I know, but I am an optimist.

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  17. I happen to be sitting in the Lagos office of a major multinational oil company. They have screen savers on their PC network that warn of how many children malaria kills and all the things that should be done to prevent it. They also have posters describing the efforts they are making to reduce greenhouse gases, mostly around reducing methane venting and flaring.

    There is no hint that the two issues could be related. Fix methane venting and flaring? Yup, good idea. Take your Malarone and drain the ditches? Yup, good idea. One does not depend on the other.

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  18. for the sake of clarity, I meant incentive, natch

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  19. ooof that Sarewitz essay is a piece of work. Crikey. Thanks Roger, good answer ......

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  20. It is reading claims about malaria and other pretended health problems related to global warming that turned me into a 'skeptic'.

    I am frequently in southern Tuscany, that was a malarial area as recently as in the 1940'. Now it is a completely healthy and prosperous part of Italy - and you don't need to be an expert to see that no change in temperature or weather is going to bring malaria back.

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  21. This is yet another example of the what John Maddox wrote about in "The Doomsday Syndrome":
    Scientists and others taking bit of theory and a lot of hype and making claims of doom that fall apart under modest scrutiny.

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  22. Eric144, Good to see BBC cover this, Australian Government media, the ABC, on the other hand, remain in denial...

    http://abcnewswatch.blogspot.com/2010/05/malaria-climate-link-de-bunked-but-will.html

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  23. DDT. The enviros have killed millions by going after DDT. Of course, for a lot of enviro whackos the dead people are a feature, not a bug.

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  24. Sarewitz' article is great. BTW, I just got your book yesterday, and am enjoying it. Open discussion of these issues of science and advocacy is what we need.

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  25. Re Weitz’s quote:
    “Environmental activists use the ‘big talk’ of science to create a simple but false paradigm. Malaria specialists who protest this are generally ignored, or labelled as ‘sceptics’."

    I would say that this has become a pattern – climate scientists and a set of generalized kinds of scientists and others make projections about something- malaria, forestry, agriculture. They do not employ the scientists who are actually experts in the field, nor practitioners, who have spent their lives studying these topics.

    They publish this work in journals- say Science or Nature- which would seldom publish an article from one of these applied fields on its own- generally when a paper supports a specific paradigm and have political significance.

    Then when the real experts protest, they gnerally have nowhre to go, since the main journals and mainstream media do not provide opportunities for the small voices. Until the advent of bloggery, that is.

    Perhaps there should be a rule that when papers study impacts on some topic, that a draft of that paper be published on the web and comments requested from all the involved disciplines.

    Finally, I don’t see how the idea of “ecosystems are more complex than we think, they are more complex than we can think” from the ecological literature (I know, paraphrased from Haldane, who was a population geneticist) can be harmonized with the idea of “we know that climate change will have these impacts.” We could be seeing the beginning of a match- science vs. Science. Perhaps there will be a video ;)?

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  26. Mitigation of the effects has long been touted (and long ignored) as the sensible response to climate change. As for GW, the point may soon be moot if Dr. Adussamatov of the Pulkovo Observatory is correct.

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  27. The memory of some science it's short. These findings and "new studies" are on the table years ago thank's to Paul Reiter, the media and AGW advocates ignore him.

    This Climate Science need more real science.

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