IPCC Wrong Again on Malaria and Mosquitoes.

One of the many dangers of global warming being thrown around is the increased incidence of malaria in Africa.  The theory being that warmer climate would allow mosquitoes to transmit malaria to higher altitudes as the climate warmed up.  Year after year it has been thrown out that malaria will rise as a result of global warming.  Considering the typical accuracy of the IPCC, it should be no surprise that they are once again completely wrong.

A new paper from Malaria Journal is claiming that there has been an unexplained and dramatic DECREASE in the mosquitoes that cause malaria.  The drop over the past 20 years cannot be explained by activities to reduce mosquitoes and the drop is ~100%.  They actually put the percent drop at 99.7% and 99.8%, but you will excuse me if I round that up a tiny amount.   This qualifies as a significant drop in the mosquitoes that transmit malaria.

The paper itself discusses if the previously unexplained drop in malaria is caused by the drop in the mosquito population and that would appear to be the case.  The drop is so large that the BBC article on the paper has the following quote:

Prof Meyrowitsch added: “Other scientists are saying they can’t test their drugs because there are no children left with malaria.

So the latest science shows that malaria infection rates are dropping and the likely cause is a decrease in the disease carrying mosquito population.  This certainly is contrary to the predictions of the IPCC.

So what is causing the drop in the mosquito population?  The paper also covers that.  There is this ambiguous statement that might suggest that rainfall patterns are the culprit:

Part of the decline could be associated with changes in the pattern of monthly rainfall

But the results section contradicts that statement with the precise statement of:

With the exception of the decline in An. gambiae during the 1st period, the results did not reveal any statistical association between
mean trend in monthly rainfall and declining malaria vector populations.

So the results of the paper are that there is no statistical association between the trend in monthly rainfall and the decline the the mosquito populations in question.  The climate does not appear to be the cause of the drop in the mosquito population.  The chart for the mosquitoes captured and the monthly rainfall show the accuracy of the statement.

The Inconvenient Skeptic

(Fill) Monthly rainfall. (lines) Trapped Mosquito by species.

While this trend may reverse itself in the future, it is obvious that the projections of the IPCC are basically meaningless because there is so much that still needs to be learned about the ecosystems of the Earth.  They create a theory that sounds plausible if the Earth warms, but in the end, the observations keep failing to match the predictions.

In the meantime the people in Africa are experiencing a decrease in a devastating disease and everyone should rejoice in that news.  For those that question the methods and motives of the IPCC, this is just one more example of real world observations showing the opposite of what is predicted by the IPCC.

Posted in Fear and Misinformation and Politics and Global Warming by inconvenientskeptic on August 29th, 2011 at 12:51 am.


This post has 11 comments

  1. Prevalence of malaria and related haemosporidian parasites in two shorebird species with different winter habitat distribution


    Malaria is found in the Arctic region.

  2. From Shakespeare to Defoe: Malaria in England in the Little Ice Age


    Malaria has infected people in cool summer regions.

  3. ARWallace Sep 1st 2011

    I hope your book is not written with the accuracy you show in this post. You seriously misrepresented the story.

    The article basically gives three reasons for the drop in malaria.
    1) “Controls such as anti-mosquito bed nets”, and …wait for it…
    2) Climate change caused “chaotic” rainfall. Yup, that is the next explanation given, but the lead author is not convinced it is “just” climate change, so what other factors might be involved.
    3) Disease, fungi, or other “environmental” changes.

    So basically the story says that changes in rainfall and related factors (possibly caused by climate change) can influence mosquito populations and effect malaria. In this case, it is for the better. What happens if it increases or evens out the rainfall?

    Basically, you take a story about a single country where climate change may be having a positive effect on one aspect of life and extrapolate it to the rest of the world. Because you also want to ignore evidence of climate change you discount that part.

    Please be more careful. My sense is this kind of argument is what gives anti-AGW folks a bad name.

  4. inconvenientskeptic Sep 1st 2011


    The point being that the IPCC predicted the opposite. The increase of malaria has long been a theorized threat of global warming. The IPCC prediction is wrong which is why the article has the title that it does.

    The journal paper was one country, but the BBC article stated:

    Data from countries such as Tanzania, Eritrea, Rwanda, Kenya and Zambia all indicate that the incidence of malaria is dropping fast.

    So multiple countries covering a large area are showing reduced malaria rates and in one case the cause is known to be a reduction in mosquitoes, but no one knows why the mosquitoes are being reduced, but it doesn’t correlate to rainfall.

    The science does not support the theory that malaria is on the increase as predicted by the IPCC.

  5. inconvenientskeptic Sep 1st 2011


    Much of the developed world has succeeded in eliminating malaria which was prevalent around the world until 100 years ago.

    That it was more widespread in the past when it was cooler is perhaps an indicator that the entire idea of temperature dependence of mosquitoes was always a weak idea. Certainly Minnesota has plenty of mosquitoes and its average temperature is relatively low.

  6. ARWallace Sep 1st 2011

    I’m just pointing out you are doing the same thing as the AGW folks. Your logic is this:

    Premise from the IPCC: AGW could lead to the extension of malaria in the future (decades from now).
    Test: Right now after < 1C warming, in a few places, from a non- standard sample, Malaria may be dropping.That might be from climate change, but no one knows.
    Conclusion: AGW will not cause the spread of malaria.

    This seems pretty sloppy to me. I just thought I would point it out.

  7. inconvenientskeptic Sep 1st 2011


    That is a fair point. It is certainly too early to draw significant conclusions based on short-term trends. Using my own methods against me. 🙂

  8. Eric Anderson Sep 2nd 2011

    Why would anyone in their right minds think that mosquito populations don’t thrive at higher elevations and higher latitudes? Anyone been to northern Canada or Russia or high in the Rocky Mountains? The mosquitoes love it!

  9. Eric Anderson Sep 2nd 2011

    AR, I understand your point, but the situations are not symmetrical. On the one hand we have someone putting forward a hypothesis: that malaria will extend in a meaningful way as a result of global warming. On the other hand, we have someone noting that, so far the (yes, limited) data suggests that the hypothesis may not be on solid footing. The scare hypothesis doesn’t get to become the null hypothesis (which must then be proven wrong or must wait decades to see if it unfolds) just by virtue of it being uttered. Until there is good evidence to believe global warming will cause a spread in malaria, one is perfectly justified in taking it with a grain of salt.

  10. The two links I posted was just a sampling.To show that Malaria has been present in a lot of cool to cold locations.

    The idea that GW will spread it to cooler regions,is faulty.They are already there! The incidence of the infection will probably increase with GW in the cool regions.Since warmer weather there will improve the chances for the Malarial virus to infect people.

  11. I see this type of result regularly. If the news is bad then AGW is the cause, if the news is good then AGW is not the cause. In this case, malaria decreased so AGW is not the cause. Had malaria increased, AGW would definitly have been to blame.

    A few years ago salmon biologists were concerned that the west coast salmon run was gradually deminishing, they claimed AGW was the cause. However, last year the salmon run was the biggest in 100 years, but low and behold AGW was found not responsible. The biologists could not present an explanation for the increased salmon population and thus needed to do more research.

    This is so predictable now.

    Climate science is a new political science.

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