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.
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
ha ha – andy demands a correction.
oh, oh, oh! he’s better at comedy than science, for sure.
“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?”
No. This is no indictment at all of the hypothetical increase in the range of the *human* malaria parasite P.falciparum.
First of all a different species of parasite that infects rodents was studied. There is a notorious lack of crossover between rodents and humans in areas like this. If every potential drug that worked wonders in lab rats worked equally well in humans it wouldn’t take ten years to get a new drug to market and we’d have a whole lot more great drugs in our pharmaceutical war against disease arsenal
Secondly the study was done in the wrong range of temperatures. P.falciparum has a limited latitudinal range because it can’t survive for long in temperatures below about 45F so it dies in the winter in many regions unless the mosquito where it is obliged to spend part of its life cycle is sheltered from the cold. This would happen often in human dwellings in the past which is why it was a problem in northern climates in the past. Trade by ship between the tropics and temperate zones would also ensure that the parasite had a way to be reintroduced in northern areas during the summer months.
It’s almost a dead certainty that P.falciparum will extend its natural range should conducive warming come about.
Andy Revkin (@Revkin) says:
December 21, 2011 at 5:19 am
“Cooling Fear of a Malaria Surge from Warming.”
Wow. Backpedaling at the CAGW cultists.
Five stages of Death: Bargaining.
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.”
Your link points to this WUWT post, not to the Stockholm convention.
UNEP pressures countries into stopping DDT use, violating the spirit of the Stockholm convention.
http://www.medicalnewstoday.com/articles/223191.php
You can always count on the UN when it’s about depopulating the planet.
This study is obviously from the Duh! File. Just a quick glance at a map of malarial regions would show that there’s no correlation between temperature and malaria.
@AndyRevkin
Mr. Revkin, while the post you linked speaks to the iffy link between warming and the spread of malaria, it uses the argument that warming increases the transmission dynamics but these are overcome by mitigation efforts. The article that is the subject of this post clearly shows that warming may actually decrease the transmission dynamics.
So even if your post in 2010 came to the right conclusion, it was for the wrong reasons and was based on an incorrect assumption, namely that the transmission dynamics would increase.
Would be nice to see a post that admits that the transmission dynamics may decrease with warming as this study shows.
KD
Andy Revkin (@Revkin) says:
December 21, 2011 at 5:19 am
“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….”
My emphasis. That’s why I was careful to say it was the parasite’s *natural* range that would extend if conducive warming occurred. It’s unnatural range is a different matter. It was unnaturally extended far into temperate climate zones with the unwitting aid of humans and it was purposely forced out of some marginal zones through human eradication efforts as well. But none of this changes the fact that it cannot survive where winter temperature routinely falls below 45F for extended periods of time. The south eastern US is a marginal zone, for instance, and so armed with a little knowledge and a whole lot of DDT it was essentially driven completely out of the US and has failed to regain a foothold.
http://www.parasitesandvectors.com/content/pdf/1756-3305-4-92.pdf
Above is a link to a temperature dependence study of P.falciparum and P.vivax which are the only malaria parasites of concern to humans with the former being the most virulent and least able to tolerate cold temperatures.
Global maps are produced which illustrate with shading the average number of “infectious days” there are in any particular climate zone. Above the northern US border it’s essentially nil for the more virulent strain and increases to 365 days only in the southernmost tip of Florida. The key is that temperature must remain above a certain point long enough for the parasite to complete that portion of its life cycle that is outside the human host. It’s probably in the article somewhere but I recall that temperature is 65F for P.falciparum and the length of time is about 7 days but that’s not written in granite as individual parasites through natural genetic variability have more or less sensitivity to low temperatures. Thus if the parasite is somehow introduced into a region where it cannot survive over the winter (such as most of the United States) it can become a problem or if there happens to be a warm wet basement somewhere where mosquitos can breed year-round…
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.
The 21st century Environmentalists now wish to deprive Africans of the right to industrialize, by depriving them of cheap energy (Coal). This enforced poverty will kill more African’s than the ban on DDT.
The industrialized world was built on Coal. It is cheap, plentiful, and found almost everywhere. Environmentalists consider coal the equivalent of death (Hansen’s death trains). Yet, most of us alive today would not be here if it wasn’t for the advances made possible through coal.
Without industrialization, the earth’s human population would be only a fraction of what it is today. High birth rates would be the norm because children would routinely die before reaching maturity. Most of our time would be spent working the fields, as the most abundant form of cheap energy would be human beings.
Humans are low cost forms of energy. They feed and repair themselves, and any surplus work you can get from them is profit. Coal and oil displaced humans as a source of energy largely because it was so cheap as to be competitive.
@Andy Revkin:
Andy, is this quote from ThinkProgress in 2010 correct?
“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.”
If not, will you ask Joe Romm for a correction?
Dave Springer says:
December 21, 2011 at 6:36 am
it can’t survive for long in temperatures below about 45F
manny says:
December 21, 2011 at 4:40 am
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.
Anyone that has visited Canada in the summer knows that mosquitoes have no problem surviving cold winters. Infected Humans are the cause of malaria, because without treatment the disease survives for years in the human host, unless it kills the host.
If higher temperatures increased infection rates, mammals would not increase their own body temperature during times of infection, as they would be killing themselves. Over time, those individuals would be weeded out by natural selection.
If anything, increased body temperature in mammals during infections argues that increased temperatures reduce infection rates and thereby allows more individuals to survive.
chuck nolan says:
December 21, 2011 at 4:39 am
“EDITORIAL
Bring Back DDT, and Science With It
By Marjorie Mazel Hecht”
While I would agree with some of the points made in that article, but I would be careful quoting from a publication started by Lyndon LaRouche, but that’s just me…
Eric Worrall says:
December 20, 2011 at 11:49 pm
“We also fought a successful battle to eradicate Malaria mosquitoes, ”
With just a quick look, I didn’t find historical references for “covering swamps in a thin layer of Castor Oil” – but as a horse owner with watering troughs I am advised to use just about any oil (corn, motor, others) to kill larva. While I did not find the sort of story I went looking for I did find a story about yellow fever in Tallahassee in 1841. It is instructive regarding medical progress.
http://tallahasseemagazine.com/index.php?option=com_content&task=view&id=835&Itemid=123
To recap:
and
I see two different view from Andy. Maybe I am reading it wrong, advance apologies if I have.
Nick Stokes,
Your comments are patently false. Aid was tied to the cessation of DDT. Mozambique as an example at one point had 80% of its budget tied to donor funds-and donor funds were tied to no DDT. http://www.panna.org/ddt
And http://www.fawco.org/index.php?option=com_content&view=article&id=1058:world-malaria-day-25th-april-ddt-is-not-the-answer-&catid=19&Itemid=174
More importantly you seem unaware of the role of DDT in mosquito aversion. While it is true in some areas mosquitos are now resistant to DDT they still show an aversion response to DDTs presence (not true of other pesticides) making it the perfect application for ITNs and the coating of interior dwellings. DDT’s persistence and safety to humans makes it a critical tool for those villages that cannot be reached on a continuing basis by the limited health. http://www.kaisernetwork.org/daily_reports/rep_index.cfm?DR_ID=41219
We need a new malaria narrative. My story -malaria is a tragedy we should no longer allow. It can be eradicated if we make a commitment to do so. It will be hard, we will make mistakes, it will require all the tools we have, and perhaps some we don’t yet have (vaccine). It requires focus, funding, attention to detail, adapting, questioning and learning. None of this will happen if malaria is allowed to become a weapon wielded by ideological warriors on either side of the climate wars.
Once we allow a problem to enter the ideological arena- the goal becomes winning. Unfortunately, the first casualty is any hope we had of fixing the problem.
Any idea how many lives that $1.8 million grant would have solved if it went to bed nets or anti-malarials?
Nick Stokes says:
December 21, 2011 at 1:21 am
Eric Worrall says: December 20, 2011 at 11:49 pm
Regarding: DDT use for malaria control
Apparently this is a complex issue that ought not be expressed in “blog bites.” See, for example :
http://www.cbgnetwork.org/1180.html
Also not forgetting the one of the World’s leading experts on the subject of Malaria. Prof Paul Reiter.
I believe from memory. Didn’t he have a lawsuit to get his name removed from the IPCC?
The Distortion of the Malaria Issue by the UN and Al Gore – from The Great Global Warming Swindle
DirkH says: December 21, 2011 at 6:52 am
“Your link points to this WUWT post, not to the Stockholm convention.”
Sorry about that. Here it is.
Pat Moffitt says: December 21, 2011 at 11:44 am
“Your comments are patently false. Aid was tied to the cessation of DDT.”
You’ll need to substantiate that better. I couldn’t find it in your links. And they were campaigning against DDT use, which clearly means someone is using it.
I believe some US anti-malaria programs stopped using DDT following the Nixon admin ban. But there was no international ban, and UN agencies kept using it. And I know of no tying of general aid to cessation of DDT use for insect control.
And as John Hultquist says, it isn’t simple. Sri Lanka stopped using it in the mid 60’s, simply because insect resistance had made it ineffective (they later resumed).
Nick Stokes,
So, tell me where I can buy some DDT. At my local Home Depot? Where, if it’s not banned?
Marian says:
December 21, 2011 at 12:28 pm
“Also not forgetting the one of the World’s leading experts on the subject of Malaria. Prof Paul Reiter.”
Recent comment on that video on YouTube.
Which, everyone knows, is owned by Google, and we know about Google’s AGW bias.
So if everyone embeds this video on their website, it will begin to circumvent the Google AGW bias…I think…but I haven’t been ‘peer reviewed’.
@dutchflats It will be now! It just got posted on “Watt’s Up With That” “…the world’s most viewed climate website.” So that may be changing!
atnguy 3 minutes ago
Smokey, read the report I linked. About 5000 tons a year are manufactured. It’s banned by Stockholm convention for agricultural use, not for disease control. I’m not sure whether the 1972 US ban had that exemption – it may be that if you can convince the authorities you have a malaria problem, you can get some. In fact, they’ll probably spray you for free.
Nick Stokes,
Why should I have to convince anyone of anything if DDT is not banned? Maybe I just want to get rid of pesky mosquitoes or bedbugs. So once again: where can I buy some DDT if it isn’t banned?
Nick,
Do you agree that DDT has some unique aspect related to the mosquito’s aversion to even entering a room where DDT has been sprayed. An important fact even if it doesn’t directly kill mosquitos.
Some more on-defacto DDT bans (you don’t have to ban the sale if you link the aid to not using it as has been the repeated pattern of the World Bank (see 1997 loan to India) and the UN’s push away from vector controls. Here are some more:
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1117705/?tool=pmcentrez
from an article in the British Medical Journal
“It is possible that DDT will be used again in Mozambique. Its use there was stopped several decades ago, because 80%of the country’s health budget came from donor funds, and donors refused to allow the use of DDT.”
And this paper that found a link to reduced DDT spraying and malaria reemergence in South America
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2627649/pdf/9284373.pdf
“Countries are banning or reducing the use of DDT because of continuous international and national pressures against DDT (e.g., the International Pesticide Action Network is “…working to stop the production, sale, and use…” of DDT [14]) and aggressive marketing tactics of producers of more expensive alternative insecticides. It has become easier for political pressures to succeed given the global strategy to deemphasize use of the house-spray approach to malaria control.”
I am a non-scientist, and like the other Australian who linked to the recent Australian report, I was extremely sceptical about what it stated, considering the report to be total alarmism.
Here are my reasons:
1. that particular report mentioned Dengue Fever, and claimed we would see a massive increase of cases (as the mosquito moves South). A little bit of research (all of 5 seconds on Google) produced a report from the Queensland and Victorian governments which is worth considering. With regard to Dengue Fever, the mosquitoes cannot carry the disease unless they bite the human host first. The method by which the Dengue Fever is carried in Australia is for a human host to have been bitten in one of the countries in the tropics, such as Bali. That person then brings the disease into Australia. Most of the big outbreaks have been in far north Queensland, such as Cairns.
2. I assume that the same is probably true with regard to Malaria in Australia. I will have to check that out. Certainly we have malaria outbreaks in the tropics but these have not happened in a long time.
3. Other mosquitoes carry diseases such as Ross River Fever (or Virus) which can cause arthritis and encephalitis (also known as Murray River Encephalitis)
Now, my real point is that I am personally a mosquito magnet. As I was growing up, and in summer, I would end up with huge welts upon my body from mosquito and other insect bites. When pregnant with my first son I was bitten more than 100 times when I accompanied my parents to Emerald in the Dandenong mountains. The skin specialist thought it might have been scabies, but he was wrong, it was definitely mosquito bites!! Even as a mosquito magnet and being bitten so many times, I have never had any of those exotic tropical diseases, not even when I lived in Townsville and visited Cairns!!
As a result of my own personal experience, I find that reports claiming that such diseases will increase to be worthy of sceptism. A lot depends on the type of mosquitoes in a given area, as well as whether or not someone who brought the disease back from an overseas destination has then been bitten by the mosquito. That is how the epidemic starts in the first place!!