INTRODUCTION
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 information.
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
Working Groups. 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.
MALARIA
5. 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 period—roughly from the mid-15th century to the
early 18th century—that 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 1970.
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 factors—most
of them not associated with weather or climate—that 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 diseases—that is what makes them so
fascinating—and 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 rainy season.
IPCC SECOND ASSESSMENT REPORT, WORKING GROUP II. CHAPTER 18. HUMAN
POPULATION HEALTH
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
below).
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 specialists. [85]Moreover, climate models suggest that temperature
changes will be relatively small in the tropics, and carefully recorded
meteorological data—eg in the Brook-Bond tea estates in Kenya—shows 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 January 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 temperate-zone populations".
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
issues—particularly issues of health and the environment—is 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
activists—not scientists—are 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 REPORT, WORKING GROUP II. CHAPTER 18. HUMAN
POPULATION HEALTH
24. The third assessment report listed more than 65 lead authors, only one
of which—a colleague of mine—was 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 dengue—two 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 seasonality—although 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 in nature.
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 REPORT, WORKING GROUP II. CHAPTER 18. HUMAN
POPULATION HEALTH
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 experts?
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.
SUMMARY
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
In accordance with Title 17
U.S.C. Section 107, this material is distributed without profit to those who
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