Memorandum by Professor Paul Reiter, Institut
THE IPCC AND TECHNICAL INFORMATION. EXAMPLE:
IMPACTS ON HUMAN HEALTH
1. This evidence is presented to the Select
Committee to provide a perspective on the role of the Intergovernmental
Panel on Climate Change (IPCC) in compiling and assessing technical
2. I am a specialist in the natural history
and biology of mosquitoes, the epidemiology of the diseases they
transmit, and strategies for their control. My entire career,
more than thirty years, has been devoted to this complex subject.
My research has included malaria, filariasis, dengue, yellow fever,
St Louis encephalitis and West Nile encephalitis, and has taken
me to many countries in Africa, the Americas, Asia, Europe and
the Pacific. I spent 21 years as a Research Scientist for the
United States Centers for Disease Control and Prevention (CDC).
At present, I am a Professor at the Institut Pasteur in Paris,
and am responsible for a new unit of Insects and Infectious Disease.
3. I have been a member of the WHO Expert
Advisory Committee on Vector Biology and Control since 1998, and
a consultant for several WHO Scientific WorkingGroups. I have
worked for the World Health Organization (WHO), the Pan American
Health Organization (PAHO) and other agencies in investigations
of outbreaks of mosquito-borne diseases, as well as of AIDS and
Ebola haemorrhagic fever and onchocerciasis. I was a Lead Author
of the Health Section of the US National Assessment of the Potential
Consequences of Climate Variability and Change, and a contributory
author of the IPCC Third Assessment Report (see below). I have
been Chairman of the American Committee of Medical Entomology
of the American Society for Tropical Medicine and Hygiene, and
of several committees of other professional societies.
4. The comments that follow mainly deal
with the Health Chapters of IPCC Working Group II (Impacts, adaptation
and vulnerability) in the second and third Assessment Reports,
in which mosquito-borne diseases have figured prominently. But
first I need to give you some background on mosquito-borne diseases.
I will use malaria as an example.
MALARIA5. I wonder
how many of your Lordships are aware of the historical significance
of the Palace of Westminster? I refer to the history of malaria,
not the evolution of government. Are you aware that the entire
area now occupied by the Houses of Parliament was once a notoriously
malarious swamp? And that until the beginning of the 20th century,
"ague" (the original English word for malaria) was a
cause of high morbidity and mortality in parts of the British
Isles, particularly in tidal marshes such as those at Westminster?
And that George Washington followed British Parliamentary precedent
by also siting his government buildings in a malarious swamp!
I mention this to dispel any misconception you may have that malaria
is a "tropical" disease.
6. The ague thirteen times in Shakespeare's
plays. In Shakespeare's time, William Harvey dissected cadavers
of patients in St Thomas's hospital who had died of the infection.
Harvey was the first to describe the changes in the consistency
of the blood that result in the fatal complications caused by
the infection. At the end of the 17th century, a certain William
Talbor was knighted after he cured the King of an ague using a
concoction of quinine he had developed in the Essex marshes. He
later sold his recipe to Louis XIV, became Chevalier Talbor, and
died rich and famous after curing many of the aristocrats of Europe.
7. All this occurred in a periodroughly
from the mid-15th century to the early 18th centurythat
climatologists term the "Little Ice Age". Temperatures
were highly variable, but generally much lower than in the period
since. In winter, the sea was often frozen for many miles offshore,
the King could hold parties on the frozen Thames, there are six
records of Eskimos landing their kayaks in Scotland, and the Viking
settlements in Iceland and Greenland became extinct.
8. Despite this remarkably cold period,
perhaps the coldest since the last major Ice Age, malaria was
what we would today call a "serious public health problem"
in many parts of the British Isles, and was endemic, sometimes
common throughout Europe as far north as the Baltic and northern
Russia. It began to disappear from many regions of Europe, Canada
and the United States as a result of multiple changes in agriculture
and lifestyle that affected the breeding of the mosquito and its
contact with people, but it persisted in less developed regions
until the mid 20th century. 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. One of the last malarious countries in
Europe was Holland: the WHO finally declared it malaria-free in
9. I hope I have convinced you that malaria
is not an exclusively tropical disease, and is not limited by
cold winters! Moreover, although temperature is a factor in its
transmission (the parasite cannot develop in the mosquito unless
temperatures are above about 15ºC), there are many other
factorsmost of them not associated with weather or climatethat
have a much more significant role. The interaction of these factors
is complex, and defies simple analysis. As one prominent malariologist
put it: "Everything about malaria is so moulded and altered
by local conditions that it becomes a thousand different diseases
and epidemiological puzzles. Like chess, it is played with a few
pieces, but is capable of an infinite variety of situations"
10. The same goes for all mosquito-borne
diseasesthat is what makes them so fascinatingand
even the climatic factors defy simple analysis. Thus, in some
parts of the world, transmission is mainly associated with rainy
periods, whereas in others, epidemics occur during drought. In
some highland areas, the transmission is highest in the warmest
months, whereas in others, it is restricted to the cold season.
In Holland, malaria was transmitted in winter because the vector-mosquito
did not hibernate, fed both on cattle and on people, and overwintered
in houses and barns, taking an occasional blood meal without laying
any eggs (most female mosquitoes bite in order to obtain nutrition
to develop an egg batch). In the Sudan, low-level transmission
occurs during the 10-11 month dry season, when day-temperatures
are in the mid-40s. The vector-mosquito also shelters in houses,
feeding occasionally on people and waiting for the brief rains
in order to lay her eggs. Peak transmission occurs in the cooler
IPCC SECOND ASSESSMENT
GROUP II. CHAPTER
18. HUMAN POPULATION
11. This chapter appeared at a critical
period of the climate change debate. Fully one third was devoted
to mosquito-borne disease, principally malaria. The chapter had
a major impact on public debate, and is quoted even today, despite
the more informed chapter of the Third Assessment Report (see
12. The scientific literature on mosquito-borne
diseases is voluminous, yet the text references in the chapter
were restricted to a handful of articles, many of them relatively
obscure, and nearly all suggesting an increase in prevalence of
disease in a warmer climate. The paucity of information was hardly
surprising: not one of the lead authors had ever written a research
paper on the subject! Moreover, two of the authors, both physicians,
had spent their entire career as environmental activists. One
of these activists has published "professional" articles
as an "expert" on 32 different subjects, ranging from
mercury poisoning to land mines, globalization to allergies and
West Nile virus to AIDS.
13. Among the contributing authors there
was one professional entomologist, and a person who had written
an obscure article on dengue and El Niño, but whose principal
interest was the effectiveness of motor cycle crash helmets (plus
one paper on the health effects of cell phones).
14. The amateurish text of the chapter reflected
the limited knowledge of the 22 authors. Much of the emphasis
was on "changes in geographic range (latitude and altitude)
and incidence (intensity and seasonality) of many vector-borne
diseases" as "predicted" by computer models. Extensive
coverage was given to these models, although they were all based
on a highly simplistic model originally developed as an aid to
malaria control campaigns. The authors acknowledged that the models
did not take into account "the influence of local demographic,
socioeconomic, and technical circumstances".
15. Glaring indicators of the ignorance
of the authors included the statement that "although anopheline
mosquito species that transmit malaria do not usually survive
where the mean winter temperature drops below 16-18ºC, some
higher latitude species are able to hibernate in sheltered sites".
In truth, many tropical species must survive in temperature below
this limit, and many temperate species can survive temperatures
of -25ºC, even in "relatively exposed" places.
16. The authors also claimed that climate
change was already causing malaria to move to higher altitudes
(eg in Rwanda). They quoted information published by non-specialists
that had been roundly denounced in the scientific literature.
In the years that followed, these claims have repeatedly been
made by environmental activists, despite rigorous investigation
and overwhelming counter-evidence by some of the world's top malaria
climate models suggest that temperature changes will be relatively
small in the tropics, and carefully recorded meteorological dataeg
in the Brook-Bond tea estates in Kenyashows no demonstrable
warming since the 1920s. The IPCC authors even claimed that "a
relatively small increase in winter temperature" in Kenya
(!) "could extend mosquito habitat and enable . . .
malaria to reach beyond the usual altitude limit of around 2,500m
to the large malaria free urban highland populations, eg Nairobi.
This despite the fact that in the 1960s the mosquitoes were present
above 3,000m and Nairobi is at only 1,600m!
17. A similar claim was made that the dengue
vector, Stegomyia aegypti was once limited to 1,000m in Colombia
but had "recently been reported above 2,200m" One of
the authors (the activist with the 32 different specialities)
had recently published a claim (in The Lancet) that dengue
had reached 2,200m "in the past 15 years". I had pointed
out (again in The Lancet) that the publication he was quoting
had categorically stated that dengue was not found above
1,750m. Moreover, although the maximum altitude of 2,200 m for
the mosquito had been established (by two colleagues of mine)
in 1979, this was the first ever investigation of the issue, so
there was no evidence of an increase in altitude! Since that time,
he has abandoned the claim that dengue has moved to higher altitudes,
but still claims (eg in Janurary 2005 at a UNESCO conference in
Paris) that the mosquito has leapt from 1,000 to 2,200m in a matter
of 15 years.
18. In summary, the treatment of this issue
by the IPCC was ill-informed, biased, and scientifically unacceptable.
The final "Summary for Policymakers stated: "Climate
change is likely to have wide-ranging and mostly adverse impacts
on human health, with significant loss of life . . .
Indirect effects of climate change include increases in the potential
transmission of vector-borne infectious diseases (eg malaria,
dengue, yellow fever, and some viral encephalitis) resulting from
extensions of the geographical range and season for vector organisms.
Projections by models . . . indicate that the geographical
zone of potential malaria transmission in response to world temperature
increases at the upper part of the IPCC-projected range (3-5ºC
by 2100) would increase from approximately 45 per cent of the
world population to approximately 60% by the latter half of the
next century. This could lead to potential increases in malaria
incidence (on the order of 50-80 million additional annual cases,
relative to an assumed global background total of 500 million
cases), primarily in tropical, subtropical, and less well-protected
19. These confident pronouncements, untrammelled
by details of the complexity of the subject and the limitations
of these models, were widely quoted as "the consensus
of 1,500 of the world's top scientists" (occasionally
the number quoted was 2,500). This clearly did not apply to the
chapter on human health, yet at the time, eight out of nine major
web sites that I checked placed these diseases at the top of the
list of adverse impacts of climate change, quoting the IPCC.
20. The issue of consensus is key to understanding
the limitations of IPCC pronouncements. Consensus is the stuff
of politics, not of science. Science proceeds by observation,
hypothesis and experiment. Professional scientists rarely draw
firm conclusions from a single article, but consider its contribution
in the context of other publications and their own experience,
knowledge, and speculations. The complexity of this process, and
the uncertainties involved, are a major obstacle to meaningful
understanding of scientific issues by non-scientists.
21. In the age of information, popular knowledge
of scientific issuesparticularly issues of health and the
environmentis awash in a tide of misinformation, much of
it presented in the "big talk" of professional scientists.
Alarmist activists operating in well-funded advocacy groups have
a lead role in creating this misinformation. In many cases, they
manipulate public perceptions with emotive and fiercely judgmental
"scientific" pronouncements, adding a tone of danger
and urgency to attract media coverage. Their skill in promoting
notions of scientific "fact" sidesteps the complexities
of the issues involved, and is a potent influence in education,
public opinion and the political process. These notions are often
re-enforced by attention to peer-reviewed scientific articles
that appear to support their pronouncements, regardless of whether
these articles are widely endorsed by the relevant scientific
community. Scientists who challenge these alarmists are rarely
given priority by the media, and are often presented as "skeptics".
22. The democratic process requires elected
representatives to respond to the concerns and fears generated
in this process. Denial is rarely an effective strategy, even
in the face of preposterous claims. The pragmatic option is to
express concern, create new regulations, and increase funding
for research. Lawmakers may also endorse the advocacy groups,
giving positive feedback to their cause. Whatever the response,
political activistsnot scientistsare often the most
persuasive cohort in science-based political issues, including
the public funding of scientific research.
23. In reality, a genuine concern for mankind
and the environment demands the inquiry, accuracy and skepticism
that are intrinsic to authentic science. A public that is unaware
of this is vulnerable to abuse. After careful review of the pronouncements
the Health chapter in Working Group II the IPCC Second Assessment,
it is my opinion that that they were not based on authentic science.
IPCC THIRD ASSESSMENT
GROUP II. CHAPTER
18. HUMAN POPULATION
24. The third assessment report listed more
than 65 lead authors, only one of whicha colleague of minewas
an established authority on vector-borne disease. I was invited
to serve a contributory author on the health chapter
25. My colleague and I repeatedly found
ourselves at loggerheads with persons who insisted on making authoritative
pronouncements, although they had little or no knowledge of our
speciality. At the time, we were experiencing similar frustration
as Lead Authors of Health Section of the US National Assessment
of the Potential Consequences of Climate Variability and Change
(US Global Change Research Program). After much effort and many
fruitless discussions, I decided to concentrate on the USGCCRP
and resigned from the IPCC project. My resignation was accepted,
but in a first draft I found that my name was still listed. I
requested its removal, but was told it would remain because "I
had contributed". It was only after strong insistence that
I succeeded in having it removed.
26. Our deliberations in the USGCCRP are
"public domain", ie they can be accessed by any member
of the public. This is not the case for the IPCC. The final documents
of the USGCCRP included clear statements of the complexity of
the subject, and the limitations of models as predictors. We fought
hard for the language of the document, and prevailed against fierce
opposition, even to the point of insisting on the inclusion of
a large map that clearly showed how dengue in Texas was limited
by lifestyle, not climate.
27. My colleague was a top civil servant.
He felt obliged to sit the IPCC project out, and to attempting
to force a compromise. In a sense I believe he (we) succeeded.
The 2001 report is much more comprehensive, more accurate, and
gives a much better perspective of the diseases and their dynamics.
The selection of references was biased towards models that predict
an increase in range and prevalence of mosquito-borne disease,
but there were refreshingly frank statements on the fundamental
limitations of such models. Thus, the summary for policymakers
made the following statement: "Many vector-, food-, and water-borne
infectious diseases are known to be sensitive to changes in climatic
conditions. From results of most predictive model studies, there
is medium to high confidence that, under climate change scenarios,
there would be a net increase in the geographic range of potential
transmission of malaria and denguetwo vector-borne infections
each of which currently impinge on 40-50 per cent of the world
population. Within their present ranges, these and many other
infectious diseases would tend to increase in incidence and seasonalityalthough
regional decreases would occur in some infectious diseases.
In all cases, however, actual disease occurrence is strongly influenced
by local environmental conditions, socioeconomic circumstances,
and public health infrastructure".
28. Transmission models are not a forecasting
device. They are merely a means for exploring the interaction
of a selection of relevant parameters. Moreover, there is no realistic
way to test them in nature, nor any means to determine the "confidence
limits" of their "predictions". No statistical
evidence was given of the basis for these confidence limits; they
appear to have been a purely subjective judgement, with no clear
evidence as to why we should expect an "increase in incidence
and seasonality" in the "present ranges" of malaria
and dengue with "medium to high confidence". In my opinion,
therefore, the sentence beginning: In all cases . . .
should have come before any mention of the models, together
with a clear statement that the models were purely speculative
29. Thus, despite the improved quality of
the Third Assessment Report, the dominant message was that climate
change will result in a marked increase in vector-borne disease,
and that this may already be happening. The IPCC message has been
repeated in the publications of other Agencies, often with inaccuracies
that appear to have their origin in the Second Assessment Report.
Thus the US Environmental Protection Agency persists in making
the statement: `Global warming may also increase the risk of
some infectious diseases, particularly those diseases that only
appear in warm areas. Diseases that are spread by mosquitoes and
other insects could become more prevalent if warmer temperatures
enabled those insects to become established farther north; such
"vector-borne" diseases include malaria, dengue fever,
yellow fever, and encephalitis'.
30. Activist organizations, such as the
World Wildlife Fund, continue to quote the IPCC statement that
malaria can only be transmitted in regions where winter temperatures
are above 16ºC. Several such organizations even claim that
isolated cases of malaria in the USA and Canada during "particularly
warm and humid periods" are compatible with the IPCC projections.
IPCC FOURTH ASSESSMENT
GROUP II. CHAPTER
18. HUMAN POPULATION
31. It will be interesting to see how the
health chapter of the fourth report is written. Only one of the
lead authors has ever been a lead author, and neither has ever
published on mosquito-borne disease. Only one of the contributing
authors has an extensive bibliography in the field of human health.
He is a specialist in industrial health, and all his publications
are in Russian. Several of the others have never published any
articles at all.
32. The list of authors is of personal interest:
I was nominated by the US Government to serve as a Lead Author.
Nomination is a formal process, involving government officers
at the highest level.
33. When I contacted IPCC personnel (at
the Meteorological Office in Exeter) to see whether my nomination
had been accepted, I initially received the message: "The
IPCC received over 2000 government nominations during this process
and most, such as yours, were of a very high standard. Unfortunately
the IPCC Working Group Two Bureau did not pick you to be an author,
although all nominations were scrutinised and assessed".
34. I replied with a question about the
two Lead Authors that had been selected: "It is often
stated that the IPCC represents the worlds top scientists. I copy
to you the bibliographies of (the two lead authors), as downloaded
from MEDLINE. You will observe that (the first) has never written
a single article, and (the second) has only authored five articles.
Can these two really be considered "Lead authors" with
experience, representative of the world's top scientists and specialists
in human health?"
35. I also pointed out that one Lead Author
is a "hygienist", the other is a specialist in fossil
faeces, and both have been co-authors on publications by environmental
activists. I received the reply: "The selection criteria
for IPCC Authors are defined in the "Principles and Procedures
Governing IPCC Work" available on the IPCC website at: http://www.ipcc.ch/about/procd.htm
(These `Principles and Procedures' have been discussed, amended
and agreed by Governments at several IPCC Plenaries)".
36. I pursued the question further, asking:
(1) Who selects the Working Group/Task Force Bureau Co-Chairs?
(2) Who are the Working Group/Task Force Bureau Co-Chairs for
Group II, Health Impacts? Where is the Working Group/Task Force
Bureau? (3) What are the criteria they use for identifying appropriate
37. I received two replies, the simplest
of which read: "Thank you for your continued interest
in the IPCC. The brief answer to your question below is `governments'.
It is the governments of the world who make up the IPCC, define
its remit, and direction. The way in which this is done is defined
in the IPCC Principles and Procedures, which have been agreed
by governments. Please refer to my emails of 2 and 3 September
for details on how to access that information".
38. In all the rules that were quoted, there
was no mention of research experience, bibliography, citation
statistics or any other criteria that would define the quality
of "the worlds top scientists".
39. After all this correspondence, quite
unexpectedly, I receive another message an IPCC person in Exeter:
"I was looking today at the Access database which we use
to manage the government nominations for the Fourth Assessment.
I thought I would take the chance to check on your name. It turns
out that you were not nominated for the Health chapter. You were
nominated for the regional chapters, the four synthesizing chapters
(17-20), and chapters 1 and 2".
40. I contacted Washington. They sent me
the full set of official documents sent by executives of the Federal
Government. There was absolutely no doubt: I had been nominated
as a Lead Author for the Health chapter, and for several other
issues that involved human health.
41. The natural history of mosquito-borne
diseases is complex, and the interplay of climate, ecology, mosquito
biology, and many other factors defies simplistic analysis. The
recent resurgence of many of these diseases is a major cause for
concern, but it is facile to attribute this resurgence to climate
change, or to use models based on temperature to "predict"
future prevalence. In my opinion, the IPCC has done a disservice
to society by relying on "experts" who have little or
no knowledge of the subject, and allowing them to make authoritative
pronouncements that are not based on sound science. In truth,
the principal determinants of transmission of malaria and many
other mosquito-borne diseases are politics, economics and human
activities. A creative and organized application of resources
is urgently required to control these diseases, regardless of
future climate change.
31 March 2005
85 In 2004, 10 of these specialists published a plea
entitled "A call for accuracy" in The Lancet.
Neverthess, environmental activists continue to make this claim,
undeterred by the evidence. Back