Via the SPPI Blog – Trying to Hit a Mosquito with a Sledgehammer
Source: World Climate Report
One of the standard tenets of the global warming bible is that malaria will get worse as temperatures rise. We’ve addressed this many times before, primarily by noting that the link between high temperatures and high malaria infection rates is anything but straightforward. Infectious disease expert Paul Reiter is quick to point out that malaria has been observed inside the Arctic Circle…and this is obviously not typical of a so-called “tropical” disease.
Nevertheless, the case for a malaria-temperature relationship stands on reasonably solid ground. Mosquitoes are more active at higher temperatures so they can expand their range. Biting frequency also depends on temperature, to some extent, so this should increase the infection rate, assuming the little buggers can find enough people to bite. Fairly sophisticated models have been developed that estimate the impact of weather variables on malaria infection rates. On the face of it, this seems like a reasonably solid argument.
But in a recent paper in Nature, Oxford University’s Peter Gething and colleagues from Oxford and the University of Florida took a careful look at global malaria data to see if the predicted trend was correct.
They uncovered data from around the year 1900 showing where malaria was observed. These data not only show where malaria occurred, but also different categories of endemicity (in locations where the disease is continually present, the categories depict the approximate percentage of mosquitoes that carry the malaria parasite). 1900 is a key time because of the lack of prior malaria intervention efforts. The authors then used a current model of the parasite’s transmission to create a map at the same scale for the year 2007. The 1900 and 2007 maps are shown in Figure 1a and 1b, respectively. It’s then a simple matter to subtract the two maps to show how malaria endemicity has changed over the last 100 plus years (in this case, this is a subtraction of categories). This is shown in the bottom Figure (1c), where red shows increasing malaria and blue decreasing malaria.
There is virtually no red on the map.
Figure 1. Malaria endemicity in 1900 (a, top) and 2007 (b, middle) by increasing severity category. The difference in endemicity (c, bottom) from 1900 to 2007 indicates worsening malaria in red areas and improvements in blue (Gething et al., 2010).
If you give this issue a moment of thought, this result should be obvious. Of course malaria is not as bad now as it was 100 years ago. Global health interventions should have reduced the problem significantly.
But it has also been warming since 1900, including nearly all of the regions were malaria was endemic. Look at the problem this way: if you had available to you a) the current malaria/climate models, b) the 1900 malaria map, and c) a fairly accurate prediction of future temperatures, there is no possible way you would have predicted anything close to the map shown in Figure 1b for 2007. That’s because the climate models do not consider factors other than climate (this is also why heat-related mortality/climate model projections don’t work either).
It’s fair to say that everyone who works on this issue is pleased that malaria is less of a problem now. This speaks to the importance of intervention and awareness programs in fighting transmission. And the trend really shouldn’t be that surprising. But one might argue that regardless of the Gething et al. result, this does not mean that climate is not important.
The key part of the Nature paper, however, is the author’s attempt to quantify the effect of climate compared to other factors. To estimate these, they calculated something called the “basic reproductive number” of the malaria parasite (this is a measure of how efficiently the disease spreads within a population that has no inherent resistance to it). Even though the exact reproductive number is hard to predict, you can estimate the magnitude of the changes (also called the “effect size”) that might arise from different factors, such as climate or intervention programs.
Climate projections vary, of course, depending on the models and assumptions used, but the maximum effect sizes for the year 2050 arising from climate changes are around 2 or 3 (a doubling or trebling of the reproductive number). By comparison, the observed changes in effect size (between 1900 and 2007) were much greater than the projected climate change impact. More specifically, Gething et al.
…found that, of the 66 million km2 of the Earth’s surface thought to have sustained stable/endemic malaria in 1900, 12%, 18% and 57% had exhibited proportional decreases in the reproductive number of up to one, between one and two, and greater than two orders of magnitude, respectively; 11% had shown no evidence of change; and 2% had shown evidence of an increase in the reproductive number by 2007. Although imperfect, this simple comparison illustrates that despite warming global temperatures, the combined natural and anthropogenic forces acting on the disease throughout the twentieth century have resulted in the great majority of locations undergoing a net reduction in transmission between one and three orders of magnitude [emphasis added, Eds.] larger than the maximum future increases proposed under temperature-based climate change scenarios…When compared to the substantially smaller proposed magnitude of climate-induced effects, an important and simple inference is that [climate change impacts] can be offset by moderate increases in coverage levels of currently available interventions.
In other words, if we are really interested in stopping the spread of malaria, there are more effective ways of dealing with it than undertaking draconian global legislative efforts to reduce greenhouse gas levels—the equivalent of pummeling a mosquito with a sledgehammer.
Reference:
Gething, P.W., Smith, D.L., Patil, A.P., Tatem, A.J., Snow, R.W. and S.I. Hay, 2010. Climate Change and the Global Malaria Recession. Nature, 465, 342-346.
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Malaria is on the rise in South Africa… turn your TV on during one of the world cup matches and you can hear the buzzing of the mosquitos. I’m surprised the entire nation hasn’t been killed yet.
The beastly Sovs — as objectionable as they were — sure didn’t shilly-shally around when it came to wiping out malaria.
All one has to do is read the history of the Panama Canal to see how scary malaria would be today. About every other year, we have a mosquito borne disease that we’re supposed to be incredibly frightened of. To me, it is maddening. If we were really concerned about the diseases mosquitoes carried, we’d have the disease killed in a few days. We’re not. It is simply a scare tactic for the mind numbed youngsters today. They, apparently, don’t teach history anymore.
Peace.
Actually, one of the “standard tenets of the global warming bible” is that mosquito-borne diseases will benefit from a warming world -not malaria alone.
And why the rhetoric of the last paragraph? “Draconian” legislative efforts on AGW are not aimed solely or primarily at disease control. Has anyone seriously argued that addressing AGW is the best or the only way to stop the spread of malaria,or other disease? Has anyone credible argued that we’re not “interested in stopping the spread of malaria”? How would anyone deal with climate modulated disease except through manipulating coverage levels of currently available interventions?
@Evan Jones says: June 16, 2010 at 10:32 pm
“The beastly Sovs — as objectionable as they were — sure didn’t shilly-shally around when it came to wiping out malaria.”
But our nice friendly greenie chums, led by Rachel Carson’s pseudo science, condemned millions to die with their DDT ban.
Actually the argument that mosquitoes become more active when it is warmer is a weak one, because malaria infection most commonly takes place at night and indoors. So infection is very much a matter of bad housing, and also explains why Mosquito nets and/or occasional spraying of huts with DDT is fairly effective in preventing the disease.
In Finland for example the last malaria outbreak of consequence occurred during the Winter War 1939-40. This was a winter of epic proportions with long periods with temperatures below -40, but of course there was a lot of refugees, with many people sleeping in crowded conditions and in substandard housing, not normally used.
As late as the 1930’s malaria was endemic in much of Siberia, including Yakutia which has the coldest winters in the northern hemisphere.
—-
This is also why dire predictions about mass deaths by the year 2000 (made in the 1960s and 1970s) due to starvation as a result of the population explosion has not materialised. The only factors they saw was then current agricultural production and the rise in population without looking as potential increases in food productivity which actually occured. IMHO the same argument now applies for ‘rising’ sea levels and climate refugess.
Mosquitoes are seasonal. They have an extremely short life span. They seem to be extraordinarily feisty in the tundra. Where they attack with gusto. Nevertheless, assuming the hypothesis is true. Since the range of malaria has decreased markedly, while temperatures are approaching a death spiral according to Warmists, I think we must all question the relationship between malarial contagion and temperature. And consider the fact that numerous areas of historical infection were ameliorated by way of insecticide. That would be the Northern Hemisphere.
Hey.
Why let reality intrude on another myth created by “scientists” well outside their field, but well inside the money generated by hysteria and increased taxes.
The Soviets reduced the incidence of malaria by killing tens of millions of the host organism, i.e. humans. The AGW crowd wishes to repeat that success by making food less available.
There are some fabulous quotes on this story on the BBC:
http://news.bbc.co.uk/1/hi/science_and_environment/10127989.stm
Dr Gething. (on malaria)
“Climate change is, in our view, an unwelcome distraction from the main issues.”
Dr Gething
“A lot of the studies proposing there would be a dramatic increase in a warmer world have been met with guarded criticism, and often what’s been said about them surpasses what the actual science indicates.
“So this redresses the balance a bit.”
Chris Drakeley, director of the Malaria Centre at the London School of Hygiene and Tropcial Medicine, suggested the group’s conclusions were broadly correct.
“I am slightly sceptical of the furore surrounding (malaria and) climate change in the sense that we have to bear in mind there are other factors that are moving much faster than climate change,” he said.
“I don’t doubt climate change is happening, but we have also seen an increase in the coverage of treatment, and in the last 20 years there has been a huge amount of information and education on malaria made available in Africa; and that’s all changed much faster than the climate.”
———————–
Did you know about the Michael ‘hockey stick’ Mann climate change and malaria connection?
http://www.examiner.com/x-9111-Environmental-Policy-Examiner~y2010m5d21-Global-warming-Michael-Mann-finds-a-new-research-plaything
“But Matthew Thomas thinks differently. Matthew Thomas said that the study “plays down the potential importance of climate [change]”.
Who is Matthew Thomas? He is a researcher at… Penn State. Matthew Thomas is a researcher… at Penn State… who has just won a $1.8 million grant to study the influence of environmental temperature on transmission of vector-borne diseases. Think he has a dog in this hunt?
Ask his co-investigator on the project. Michael Mann…”
followed up here:
Global warming: Malaria and Joe Romm’s logic fail–and downright dishonesty
http://www.examiner.com/x-9111-Environmental-Policy-Examiner~y2010m5d24-Global-warming-Malaria-and-Joe-Romms-logic-fail
“After an article here was published about Michael Mann’s participation in a research study on the spread of malaria and climate change, it was only a matter of time before Joe Romm, the defender of hysteria in all matters climatological, would weigh in on the subject.”
It would be an interesting exercise to compare the reduction in malaria infections to the reduction in swamp lands that are needed by the mosquito to breed. This could explain many of the areas where large decreases have occurred.
Found in the comments section at Bishop Hill:
http://bishophill.squarespace.com/blog/2010/5/19/the-idea-of-oxburgh.html?currentPage=3#comments
“I see the malaria study by Peter Gething in Nature has caused quite a stir.
http://www.nature.com/nature/journal/v465/n7296/abs/nature09098.html
In particular, it has upset Matthew Thomas, researcher at Pennsylvania State University.
http://www.guardian.co.uk/environment/2010/may/21/climate-change-insects
You may ask who is Matthew Thomas?
Well he is Professor of Entomology, at Penn State’s Center for Infectious Disease Dynamics, who explores explores the ecology and evolution of “enemy-victim” interactions (malaria).
In 2009 he published a paper; Paaijmans, KP, Read, AF & Thomas, MB (2009). Understanding the link between malaria risk and climate. Proceedings of the National Academy of Sciences 106:13844-13849.
The Nature study by Peter Gething clearly debunks any serious link between malaria risk and climate. No wonder Matthew Thomas is angry. Gething has attacked his academic credentials, he could put Thomas out of the climate change business.
Now you may argue that is not really important.
Well it is really important to Thomas, Penn State and others. For you see Thomas was awarded a very large grant last year; “2009-2013 Quantifying the influence of environmental temperature on transmission of vector-borne diseases, NSF-EF [Principal Investigator: M. Thomas; Co-Investigators: R.G. Crane, M.E. Mann, A. Read, T. Scott (Penn State Univ.)] $1,884,991″
$1,884,991 is a lot of money to be investigating the influence of environmental temperature on malaria when such influence has now been shown to be of little consequence. It is interesting to note that you could buy a lot medicine and nets with $1.8 million.
More intriguingly is the name of one of the co-investigators – M.E. Mann.
Now that couldn’t be Michael E Mann of Hockey Stick fame, could it? Oh yes it is!
Now you see why it is so important for Penn State to discredit Gething’s study.
Mann provides the temperatures, Thomas provides the link with malaria and Penn pockets the money.
The reason for more bites of mosquitoes in warmer places has nothing to do with heat affecting the mosquitoes, rather the heat effect on people:
When it is hot, people wear less clothing, especially at night (even the modest people wear less at home). That way the mosquito have better access to human flesh.
Elementary.
@ur momisugly James Sexton:
“All one has to do is read the history of the Panama Canal to see how scary malaria would be today.”
Yes, the problems in Panama that defeated the French attempt to repeat their success with the Suez Canal are a good example. Another, more recent example of the problems caused by malaria is the experience of the British/Indian 14th Army that drove the Japanese out of Burma in World War II. At one stage the malaria rates in the 14th Army were quite horrifying, but by means of strict disciplinary action General Bill Slim was able to achieve a drastic reduction in cases, as described in the paragraph copied below from the Wikipedia article about him.
http://en.wikipedia.org/wiki/William_Slim,_1st_Viscount_Slim
“He was also concerned with the health of his troops and the impact of this on their fighting efficiency. In his book “Defeat into Victory” he tells of the malaria rates among his units being 70%, largely due to noncompliance by his soldiers with the foul-tasting quinine medication they refused to take. Slim did not blame his medics for this problem, but placed the responsibility on his officers. “Good doctors are no use without good discipline. More than half the battle against disease is fought not by the doctors, but by the regimental officers.”[47] After Slim dismissed a few officers for high unit malaria rates, the others realized he was serious and malaria treatment was enforced, dropping the rate to less than 5%. The combat effectiveness of his army was thus greatly enhanced.”
What I remember is we used to be plagued with mosquitoes here in central Pennsylvania. To go outside during the late spring to early fall we’d have to resort to numerous bug repellents, assorted sprays and the like, and still we’d end up devoured half the time.
It’s been quite a while now since they’ve been a problem. No repellents, it’s the same great outdoors outside, there might be a few bad days a year but “bad days” used to be the norm. We’ve been getting some massive mayfly swarms, here near the river, mini-marts and other places turn off most of their outdoor lights at night to avoid drawing them in. Really, it can be dangerous to inhale with your mouth open. We are told such swarms are a good thing, sign of good water quality, so I guess the water is good for the mosquitoes as well. Yet every fall at the clearance racks in the stores, many citronella candles and assorted mosquito repellents.
Long stretches of cold wet weather, so many cloudy days versus so few clear ones that depending on solar power is impractical to impossible, and now the mosquitoes seem to have gone away… It’s like something statistically significant happened over the last 15 years… 🙂
Nick:
I wonder… Do you think pretty much of the rest of the projected devastating effects of global warming might be offset by remedial interventions? One could build dykes to hold back the sea,.. One could…naw this probably isn’t even doable. Greenpea and the rest of the agw cheering section would intervene to stop this.
“(this is also why heat-related mortality/climate model projections don’t work either)”
If you need a laugh, have a look at McMichael et al on this topic
http://ije.oxfordjournals.org/cgi/content/abstract/37/5/1121
“Estimates of the temperature threshold below which cold-related mortality began to increase ranged from 15°C to 29°C; the threshold for heat-related deaths ranged from 16°C to 31°C.”
Then of course “Additional research is needed….”
How can they keep a straight face? And why on earth should they get any more money when there is plenty of serious research to be done?
Rotary International has run a huge programme over a number of years aimed at eradicating Malaria from all parts of the workd they have access to. Their programme is funded entirely by RI and its members and dispenses nets, DDT, and educates the recipients about how to soak nets in DDT, and also how to eradicate the disease-carrying mosquitos. A huge amount achieved without fanfare, to the point where ‘scientists’ and environmental advocacy groups seem unaware of this major reason for Malaria disappearing from many poorer nations. Malaria incidence will rise again when populations become impoverished and contact with agencies such as Rotary International are lost, as has occurred in parts of Africa and in other parts of the world where greedy and ignorant rulers have encriched themselves and their cohorts while their various peoples have descended into extreme poverty.
Any rise in the incidence of Malaria and other insect-borne diseases are a direct result of poverty, not a slight rise in temperatures since the beginning of the industrial revolution. Greedy despots in the undeveloped world are encouraged by the CAGW alarmists in the West to pay these ignorant/cynical governments huge reparations. Sadly, many of the West’s current political leaders see no cause to even question those ridiculous demands for ‘reparations’.
Please don’t overlook that there are various forms of malaria, with different resistance to treatment.
”
Without rapid treatment, P. falciparum malaria can cause life-threatening complications. Of those receiving treatment, about 15 to 20 percent will die. For nearly all people who do not receive proper treatment, the infection is fatal.
Read more: Falciparum Malaria Symptoms | eHow.com http://www.ehow.com/about_5082730_falciparum-malaria-symptoms.html#ixzz0r6m9OBIQ
“
My2Cents says:
June 17, 2010 at 1:47 am
It would be an interesting exercise to compare the reduction in malaria infections to the reduction in swamp lands that are needed by the mosquito to breed. This could explain many of the areas where large decreases have occurred.
Draining the swamps had a large impact on the range and severity of malaria, (aka ague), in Britain. Of course, now we don’t call them swamps, we call them wetlands and we are ‘restoring’ them at a great rate.
But if this results in an increase in malaria, AGW will be to blame, not the lovely wetlands.
Sorry – hit the wrong key.
I wished to add that the incentive to finally eradicate malaria is just as high as ever. Those who delay its eradication while they finish learned papers or complain about people getting injections are a modern equivalent of mass murderers.
The problem is how do you control for the increase in public health actions that would decrease the prevalence of malarial infections?
The hypothesis is that warmer weather will cause more malaria cases to occur outside of the previous range. Global temps have increase since 1900. Therefore once should see red in the third map outside of the areas where infections were prevalent in 1900. But you don’t.
It used to be lies, dammed lies, and statistics. Now it’s lies, dammed lies, statistics, and models.
I certainly agree with this posting … we should tackle malaria growth directly, and not via global warming-related legislation. Personally, I know of one area where malaria was previously banished but has returned. The same country has also seen a rise in viral illnesses like chickengunya.
The Great State Bird of Alaska is NOT the problem, it is only the vector by which the problem is transmitted. In our present state of healthcare and “preventive control measures” life is frairly good for most, and seemingly getting better for many more. As civilizations wax and wane the incidience of disease in all categories goes up and down.
On the matter of throwing money at the problem, you get the biggest bang for the buck if “politics” is out of the equation. Don’t trust anything you really want to the care and management of a politician, or group thereof.
During the 1960´s Malaria and Dengue had been erradicated in most southamerica, however after the binding prohibition bill issued by the GLOBAL GOVERNANCE through its Health Secretary, the World Health Organization, both illnesses reappeared even where before were unknown, in big cities.
http://www.green-agenda.com/index.html
http://www.mitosyfraudes.org/Ingles/Killer.html