Another alarming climate myth bites the dust – mosquito borne malaria does NOT increase with temperature

This is an Aedes albopictus female mosquito ob...

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Back in 2001, the University of Florida wrote one of those “science by press release” thingy’s in Eurekalert where they speculated that global warming would increase ranges, and thus the range of mosquito borne disease.

The next year, NPR jumped into the fray with Is Global Warming Nurturing Parasites?

In 2006 it was Warming Trend May Contribute To Malaria’s Rise in Science Daily

In 2009 Gore gets bitten again by another factual blunder getting all worked up about mosquitoes in Nairobi.

Joltin Joe Romm and NYT’s Andrew Revkin agreed last year that:

The climate blogger Joe Romm and I agree (breaking news): Scientific research and assessments examining the link between human-driven climate change and malaria exposure have, for the most part, accurately gauged and conveyed the nature of the risk that warming could swell the ranks of people afflicted with this awful mosquito-borne disease.

Also in 2010, Indur Goklany did a WUWT guest post Smacking Down Malaria Misconceptions as well as this guest post from Dr. Pat Michaels where clearly the malaria data just doesn’t add up in Peer reviewed whack a mozzie.

I’m happy to report both Romm and Revkin are wronger than wrong, and the whole AGW to malaria link has just been shot down, in Nature no less, by a Penn State study. It may also be time to revist this WUWT post: Mann’s 1.8 million Malaria grant – “where do we ask for a refund’? since he didn’t contribute to this new study.

Here’s excerpts from the story in Nature:

Global warming wilts malaria

Transmission of infectious parasites slows with rising temperatures, researchers find.

by Zoë Corbyn

A common assumption is that rising global temperatures will increase the spread of malaria — the deadly mosquito-borne disease that affects millions of people worldwide. But a study out today in Biology Letters finds that warmer temperatures seem to slow transmission of malaria-causing parasites, by reducing their infectiousness.

The study was done with rodent malaria, but the researchers, at Pennsylvania State University in University Park, expect the pattern to apply to human malaria and possibly to other mosquito-borne diseases such as dengue fever and West Nile virus.

Studies predicting that warmer climates will increase malaria infections commonly assume that the disease-causing parasites will develop faster and that the ability of the mosquito to acquire, maintain and transmit the pathogen will remain constant. They conclude that as temperature rises, mosquitoes become infectious quicker and therefore malaria transmission increases.

But the latest study shows that temperature has a more complex effect. As temperature rises, parasites do develop faster, but fewer of them become infectious.

“It is a trade-off between parasite development and parasite survival,” says Krijn Paaijmans, an entomologist and study author. “And if you don’t factor this in I think you come to the wrong conclusions.”

To tease out the factors involved, Paaijmans and his colleagues incubated mosquitoes infected with Plasmodium yoelii, which causes rodent malaria, at 20, 22, 24 and 26 degrees Celsius for 5–14 days. The researchers then examined the salivary glands of the mosquitoes — where the parasite travels when it is mature — and found that the parasite developed more quickly in warmer temperatures. But they also found fewer sporozoites — the infectious form of the parasite — indicating that the mosquitoes were less infectious at higher temperatures.


Full story here

Will Romm finally shut up about mosquitoes and malaria now? Will Revkin write a story correcting his previous ones? Will Mike Mann give back the 1.8 million dollars?

UPDATE: In comments, Andrew Revkin disputes that he was “wrong” on malaria per the quote I cited from the Climate Progress article. He now points to his 2010 article: The science linking warming and malaria risk was always iffy‘ He says he was taken out of context and that his quote was poor word construct. – Anthony


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Rhoda Ramirez

Three ending questions and I suspect the answer is “No” to all of them.

Leon Brozyna

And from Penn State no less !!
There they go … mucking up a good story with all those inconvenient facts. Epidemiology, like the climate, is no simple matter.


I’m suprised that Nature has turned from its climate Orthadoxy . This is good news, atleast its 1 less (fallacious) point the fraudsters have to make in swaying the public opnion to their scam.

Reed Coray

Does this mean the “team” will try to get the editor of NATURE fired? Inquiring minds want to know.

Rhoda Ramirez

The findings of the study are interesting. I’ve always assumed that the major plagues of the late middle ages on through the colonial period were so devastating because the enviromental conditions resulted in a lower quality of life. This study seems to indicate that the infection agent itself may have been more infections at lower overall conditions.


Isn’t it getting cooler the last 10 years? Where is my malaria surge?
Bengal appears to have the highest incidence of malaria in India, and, the temperatures hit well over 100F, which is well outside the temperature range of this paper. This research may only be relevant to spring in the U.S.A. So, I wouldn’t go demanding apologies with this scant data.


Would this qualify for the FAIL files?


This is reported here from the Australian Climate Commissioner, only a month ago.
“”3. As the climate changes, infectious diseases will rise.
› The expected rise in some infectious diseases associated with increasing temperatures,
changes in rainfall, and more intense extreme weather events is of serious concern.
› dengue fever is currently confined to northern Queensland. As north-eastern Australia
becomes hotter and wetter the range of the mosquito that spreads dengue fever is projected
to move south. A southward spread could put five to eight million Australians at risk by the
end of the century, 10–16 times the population that is currently at risk.
› As average temperature continues to rise across Australia the incidence of bacterial food-borne diseases will also rise. The more vulnerable members of the community will be hardest hit
by climate change-related illness.
› The more vulnerable members of the community—the elderly, the young, those with
chronic illness, those in lower socio-economic groups and indigenous communities—are
especially at risk.
› more frequent and more extreme bushfires, droughts and floods will increasingly affect
physical wellbeing, mental health and incomes of rural Australians.””
I have refereed their media coordinator to this new study and asked that the report be formally corrected. No doubt it will be a long time coming. My persistence will allow this little mossie to suck some blood.


This should maybe go in climate fail files for reference. The whole malaria thing keeps coming up again and again. Or at least it did in the past. It’d be nice to have a quick reference to this. Other alarmist myths should go in the climate fail files too. Weren’t there several posts in the past about melting ice on mountains.


Once in a while, a good piece of science will still slip into Nature. Mann and Jones and company don’t dare try to get the editor fired there…..

The “backing away slowly” has begun?
As for malaria, you need: 1) lotsa skeeters (any standing water for breeding will assure this); 2) available food.
Which is why historically, e.g., Siberia had major outbreaks. Etc.

“Will Mike Mann give back the 1.8 million dollars?”
That would be premature. Mann did not get the grant – Matthew Thomas did. Mann was one of four co-investigators. And Matthew Thomas was one of the co-authors of this paper, which was written under that very same grant:
Paaijmans, K.P., Blanford, S., Chan, B.K. & Thomas, M.B. (accepted).Warmer temperatures reduce the vectorial capacity of malaria mosquitoes. Biology Letters.

How many times do peer-reviewed studies have to show what we all know, need to be published before the maniacs STFU about malaria and global warming!??!!??? Don’t get me wrong, I’m glad these guys engaged, but, on my unplugged 3-generations-ago-computer I have two papers that clearly state there is no connection. And, if memory serves me correctly, a comment in Lancet, from a team of people that actually know about infectious diseases, absolutely, emphatically, under no uncertain circumstances, does malaria have any connection with global warming. Are these people braindead? Why is it so important to these people that malaria be connected to global warming? Personally, I would have gone with dysentery, but that’s as easily dismissed as well. But, honestly, what part about the historical malaria outbreaks in Siberia and Alaska do they not understand?
The people arguing that malaria is tied to global warming are the reason why people give the argument of eugenics merit.


Its funny how the Pro AGW people tend to be outspoken proponents of population control, and the Anti AGW people typically take the opposite view. Al Gore and Bjørn Lomborg come to mind as fairly vocal proponents of their respective beliefs.
Since the modern day Green Progressive’s are direct philosophical decedents of the Progressives of the 1920’s and 1930’s, advocating population control should not come as a big surprise to people. At least the people that have take the time to inform themselves about the subject…I think.


From the pedant in me, you may wish to correct the spelling of borne in your headline. Though the way it reads at present gives it a very interesting meaning


Will the IPCC include this research in their next report?


James Sexton says:
December 20, 2011 at 8:34 pm
How many times do peer-reviewed studies have to show what we all know, need to be published before the maniacs STFU about malaria and global warming!??!!???

People in the grip of a cultish fundamentalist belief system usually don’t “give up” they can only be deprogrammed, or absolutely shocked out of their belief when their messiah figures are caught doing something especially dispicable to them or someone they truly care about.
Due to lack of personal interaction between the core believers and their prophets (Gore, Hanson, Mann, et al) it’s only deprogamming that will work.
Where AGW has lost “believers” is from the ranks that were not fundamentalist to begin with – such as myself (woke up in 2008).
So no STFU’ing on the horizon – this is a long march fight.

Now that I have your attention, consider the trivial “borne” vs “born” in the title. 😉
[REPLY: Happy Now? -REP]

Dr. Dave

There have been several excellent articles about malaria here at WUWT. What’s important to remember is that humans are the reservoir of the Plasmodia that cause malaria in humans. Wanna get rid of malaria in your neighborhood? Get rid of humans infected with the disease. I don’t mean get rid of the humans, per se, just get rid of the disease. Mosquitoes are only the insect vectors for transmission of the disease. Because we have seen severe outbreaks of malaria close to the arctic circle should be a tip off that the insect vectors are only one part of the equation. The trick is to break the chain. Reduce the prevalence of the insect vectors (e.g. DDT), treat and/or isolate infected individuals and pretty soon you no longer have malaria. Most of the US was malarious just 150 years ago (before global warming started). A lot of things changed in the US (and Europe). We moved indoors, we invented screens, we discovered the cinchona alkaloids (i.e. quinine and derivatives) and eventually we developed very effective pesticides. No more malaria in North America and most of Europe. EVERYBODY has mosquitoes (almost), but if you don’t have a population actively infected with malaria you’re unlikely to become a malarious region. Mosquitoes are only the vector…humans carry the disease.

David Eyles

Right up until the 1890s, malaria was endemic in the Essex and Kent marshes (low lying areas on opposite sides of the Thames Estuary). That was at the end of the period that we now know as the Little Ice Age. Warming and drainage of the marshes in the early 20th Century finished the malaria off.

This study is interesting but it was done with rodent malaria etc. The main point is that malaria hasn’t increased with increased temperatures:
I’d assumed this was because of successful interventions. It’s interesting that there may be more to the story.


Those danged complexities!

Neil Jones

I assume that’s now in the “FAIL” file

Dennis Nikols, P. Geo

To answer your questions probably not. This is not and never was about science in the first place so whey would anyone expect behavioral changes in these people.

Nigel S

David Eyles says:
December 20, 2011 at 10:26 pm
Re: UK malaria
A bit more recent than early 20th Century (last UK case was 1952 on the Isle of Sheppey) but as Dr Harbach (quoted in the Daily Telegraph) confirmed the mosquitoes were just the vectors.
‘Dr Ralph Harbach, of the Natural History Museum in London, said that there could not be an outbreak of malaria unless someone in the island already suffering from the disease were bitten by a mosquito that then bit other people.
He said: “This is how the man died in 1952. Soldiers coming home from foreign countries were bringing malaria into Britain. The mosquitoes were passing it on to others from them.”‘


When pigs fly, when hell freezes over and no.


We can be assured and relieved that CAGW fanatics will devote just as much energy to spreading “good news” like this as they did to spreading alarmist news when they thought that the “malarial mosquitoes hypothesis” served their agenda. (sarcasm alert)

Malaria was endemic in Northern Russia and Siberia, during the Little Ice Age.
Suggesting Malaria is a tropical disease is pure hokum. The only reason we dont face Malaria epidemics on the same scale as the tropics does, is many of the swamps in developed countries, where the Mosquitoes used to breed, got drained, paved over, and sold as housing estates.
We also fought a successful battle to eradicate Malaria mosquitoes, with techniques ranging from the 19th century method, of covering swamps in a thin layer of Castor Oil, to spraying infested areas with chemicals like DDT.
Of course, when Africa started using DDT, we banned it.
Of all the crimes against humanity committed by 20th century Environmentalists, history may judge their worst crime to be the murder of millions of Africans, by depriving them of the means to control Malaria.


Off topic – but in the same vein – here is a story from the BBC where trees are dying but amazingly not declared due to climate change!!

Interesting article, although as David Stern already pointed out the study in question was performed with rodent malaria. I imagine that it is pretty safe to assume that ‘human’ malaria acts in the same way to temperature changes, but it would it unscientific to state that the issue has been ‘settled’ without direct experimental evidence, would it not…?

Eric Worrall says: December 20, 2011 at 11:49 pm
“Of all the crimes against humanity committed by 20th century Environmentalists, history may judge their worst crime to be the murder of millions of Africans, by depriving them of the means to control Malaria.”

That isn’t true. DDT use for malaria control was never banned by the Stockholm Convention, and continued in Africa (and India and S Am) throughout. Its use diminished because of insect resistance. Here is a recent Stockholm Convention report on the current and planned use of DDT.

Al Gored

Once again, a simplistic AGW poster story skewered by the complexity of its details. This does explode the standard myth but these details suggest that this isn’t THE simplistic ‘answer’ to it either. It is just one paper on just one species.
In the meantime, good news for rodents worried about the relentless warming.

richard verney

Didn’t Paul Reiter resign from the IPCC over this issue?
Paul Reiter is an expert in malaria and he is of the view that malaria thrives in cold conditions and the IPCC misrepresents the case that warming would lead to an increase in malaria. I am sure that Paul Reiter will welcome this latest paper vindicating his position.

richard verney

Further to my last post, the language of which was a bit sloppy. I understand that Professor Reiter holds the view that malaria is not a tropical disease and that malaria carrying mosquitos can thrive in cold climates and since it is not a tropical disease warming per se will not inevitably lead to an increase in malaria. .

dangerous sheep

I wonder if the University of East Anglia will remember that until the middle of the nineteenth century their part of England was notorious for malaria. This period was the same as the little ice age when lakes, rivers and canals in the area regulary froze over and the whole region was famous for winter skating.

wayne Job

Interesting article that makes a mockery of the alarmist non sense. I have but one problem mankind carries a disease and mozzies can spread it to other people.
This gives mozzies a bad rap, around every third generation after being vegetarian and living on plant sap, the females of the species become vampires. They need a blood diet to breed successfully , the easiest target is a naked ape, thus we are stricken by attacks of female vampire mozzies.
They are doing what is necessary for their survival . This should in no way be identified with female behaviour in general, and innuendo and sarcasm in that direction should be disregarded.
This study proves only that mozzies are doing what they do naturally, and AGW does not bother mozzies in the slightest. From the arctic to the tropics and to the netherworld of the antipodes they prosper.


Seems to me this isn’t quite a slam dunk. They only studied half the equation.
What happens to the development and transmission of the disease from the host side? Does it develop in rodents/humans faster or slower, and is it more transmissable (is that a word?), in those exact same temperature ranges? Would the overall rate of infection not be subject to both factors? If one goes down, but the other up….
Mods ~ since the transmissable sporozoites are BORN in the gut of the mosquito, the correct spelling in this case for the article title would be BORN, not BORNE. Please change it back 🙂


In climate science studies the opposite of everything is true.


This myth died a long time ago. Where is Al Gore when you need him?
One of the worst outbreaks of Malaria occurred in Russia / Siberia.
Global malaria has been on the decrease during the hottest years on the record. It’s worse than we thought!

“…..sometimes common throughout Europe as far north as the Baltic and northern Russia….
In fact, the most catastrophic epidemic on record anywhere in the world occurred in the Soviet Union in the 1920s, with a peak incidence of 13 million cases per year, and 600,000 deaths. Transmission was high in many parts of Siberia, and there were 30,000 cases and 10,000 deaths due to falciparum infection (the most deadly malaria parasite) in Archangel, close to the Arctic circle. Malaria persisted in many parts of Europe until the advent of DDT.”
Professor Paul Reiter, Institut Pasteur

I could go on with Malaria in England in the Little Ice Age, past, devastating malaria outbreaks in Finland, Norway, Canada but I think this is enough. ;O)


When was the Little Ice Age? How cold was Finland?

“A total of 1,803 persons died of malaria in the western parts of Finland and in the south-western archipelago during the years 1751–1773 [23]. Haartman [21] reports severe epidemics in the region of Turku in the years 1774–1777 and the physician F.W. Radloff mentioned that malaria was very common in the Aland Islands in 1795 [39].”
Huldén et al – 2005 Malaria Journal

Brrrrr! Why does Malaria like the cold so much?


“David Eyles says:
December 20, 2011 at 10:26 pm
Right up until the 1890s, malaria was endemic in the Essex and Kent marshes (low lying areas on opposite sides of the Thames Estuary). That was at the end of the period that we now know as the Little Ice Age. Warming and drainage of the marshes in the early 20th Century finished the malaria off.”
Hence the call to restore wetlands.

chuck nolan

Nick Stokes says:
December 21, 2011 at 1:21 am
That isn’t true. DDT use for malaria control was never banned by the Stockholm Convention, and continued in Africa (and India and S Am) throughout. Its use diminished because of insect resistance. Here is a recent Stockholm Convention report on the current and planned use of DDT.
Bring Back DDT, and Science With It!
By Marjorie Mazel Hecht
(Full text of Editorial from Summer 2002 issue &
“The U.S. decision had a rapid effect in the developing sector, where the State Department made U.S. aid contingent on countries not using any pesticide that was banned in the United States. The U.S. Agency for International Development discontinued its support for DDT spraying programs, and instead increased funding for birth control programs.
So, my understanding is that EPA administrator William Ruckelshaus made the decision to ban DDT and in every country where it was banned more people died from malaria.


Between 1826 and 1832, some 1,000 workers died of malaria while building the Rideau canal between Ottawa and Montreal, in frigid Canada. There is no malaria any more in tropical Florida. The link between malaria and climate was wrong from the start.

If Anthony had actually read the Dot Earth post he snipped from he would have seen that I was crediting Romm for acknowledging that the peer-reviewed literature did NOT point to a broadening of malaria risk. And he might have clicked on the link to the previous week’s piece that said:
Cooling Fear of a Malaria Surge from Warming.
As various arguments for action on global warming have failed to blunt growth in emissions in recent years, environmental groups and international agencies have sometimes tried to turn the focus to diseases that could pose a growing threat in a warming world — with malaria being a frequent talking point.
It shouldn’t be. The science linking warming and malaria risk was always iffy, a reality reflected in the relevant sections of the 2007 reports from the Intergovernmental Panel on Climate Change. Modeling studies cited there had variegated results, and many focused only on the potential expansion of the geographical range or mosquito-friendly seasons, while not considering how shifting patterns of health care and human behavior might render such changes moot….
Who needs to post a correction??

Sometimes I wonder if abstract and specialized education, or just too much education, is a prime cause of these insane pseudoscience cults.
An unspecialized learner is likely to have some random facts about mosquitoes in his mind, such as the famously gigantic Alaskan mosquitoes, or the malarial swamps of Northern Ohio that caused Americans to call malaria “Maumee Fever” for many years. These facts would prevent him from assuming that skeeters need tropical warmth, or that malaria needs tropical warmth.

Well, I guess Michael Mann can return that $1.8 million payola grant to study mosquito vectors. It should have gone to a biologist or epidemiologist anyway. And it would have, if it were not simply payola to keep Mann in line following Climategate 1.0.


Mosquito borne diseases depend on them having suitable habitats, NOT TEMPERATURE — namely stagnant, isolated water. They occur from the tropics to the Arctic.
How many times does this need repeating?

Smokey says: December 21, 2011 at 5:39 am
“Well, I guess Michael Mann can return that $1.8 million payola grant to study mosquito vectors. It should have gone to a biologist or epidemiologist anyway.”

It did go to a biologist – Matthew Thomas, principal investigator under the grant, and co-author of this paper. Mann was a co-investigator. The paper described in this post was funded by “Mann’s 1.8 million Malaria grant”.

Nick Stokes,
Thomas “said that the malaria map published in Nature shows that in some areas of Latin America, South and South-East Asia, and Sub-Saharan Africa, malaria will in fact increase with global warming.” [source]
As we see fro the comments here, “global warming” has no discernable effect on malaria, which occurs in all temperature ranges. But don’t let facts get in the way of your belief system.

heres another example of
its worse its worse, panic panic woe is us.