Global Climate Change: Federal Research on Possible Human Health Effects
CRS Report for Congress
Global Climate Change: Federal Research on
Possible Human Health Effects
Updated February 10, 2006
Specialist in Life Sciences
Resources, Science, and Industry Division
Congressional Research Service ˜ The Library of Congress
Global Climate Change:
Federal Research on Possible Human Health Effects
The average global temperature has risen approximately 0.6oC (0.9oF) over the
past century. Global mean temperatures are projected by recent computer models to
increase by 1.8oC to as much as 7.1oC (2.7oF to 10.7oF) over the next 100 years. It
appears likely that global mean temperature increases will continue, and projections
into the future predict a variety of possible related impacts in general, such as more
volatile weather patterns, increased incidence of hot spells, and changing
precipitation patterns that may include more intense rainfall patterns, as well as
changing and intensified drought patterns. Extensive research is underway
concerning the links between climate and human health; however, much of this
research is being done for reasons unrelated to climate change per se. This report
does not address the underlying question of climate change itself, details about which
can be found in the CRS Issue Brief IB89005, Global Climate Change, by John R.
Justus and Susan R. Fletcher. This report identifies the array of climate-relevant
human health research and discusses the interconnections. Approximately $57
million each year since FY2005 supports climate change research at the National
Institutes of Health.
Health effects research topics are very wide-ranging, including studying skin
and eye damage from increased ultraviolet radiation, effects of damaged water
infrastructure, dynamics of recovering from disasters, and ways to strengthen the
capacity in developing countries to deal with infectious diseases. Three conclusions
are common to several studies on possible health effects of climate change: the
infirm, the elderly, and the poor may be disproportionately impacted if climate
change results in more severe and/or more frequent episodes of heat waves and air
pollution; the risks of vector- and water-borne diseases may increase with global
warming, but countries and regions with adequate sanitation, surveillance, and public
health systems may not see significant increases in disease incidence or distribution;
and further research is needed to better understand the complex linkages between
climate and health.
Human health problems that may be linked to climate change are not created by
changes in climate per se; rather, they are problems independent of climate change
that may be exacerbated or intensified by changing weather patterns (climate, a
longer-term phenomenon, can be considered to be the average of shorter-term
weather patterns). Most health research is being conducted for reasons unrelated to
climate change, but researchers are alert to ways in which environmental factors
affecting health may be altered by climate change. In its oversight responsibilities,
Congress may wish to consider the priorities and coordination of federally funded
climate change health research. This report will be updated as events warrant.
Scope of This Report...............................................3
Human Health Effects Possibly Related to
Trends of Concern.................................................5
Human Health Effects Research Related to Climate Change................6
National Institutes of Health (NIH)................................7
World Health Organization (WHO)................................8
List of Tables
Table 1. Climate Change Research at the National Institutes of Health........7
Global Climate Change: Federal Research
on Possible Human Health Effects
The average global temperature has risen approximately 0.6oC (0.9oF) over the
past century. Global mean temperatures are projected by recent computer models tooooo
increase by 1.8C to as much as 7.1C (2.7F to 10.7F) over the next 100 years, with
a variety of possible related impacts, such as more volatile weather patterns,
increased incidence of hot spells, and changing precipitation patterns that may
include more intense rainfall, and changing and intensified droughts.1 At the same
time, local climate conditions may result in other temperature effects and related
impacts (the presence of sulfates from combusted sulfur-containing fossil fuels, for2
example, may limit warming in some areas).
In 1988, the World Meteorological Organization and the United Nations
Environment Program established the Intergovernmental Panel on Climate Change
(IPCC). The task of the IPCC is to assess the scientific, technical, and
socioeconomic information relevant to understanding the possible risk of human-
induced climate change. Its First Assessment Report was distributed in 1990. The
Third Assessment Report is titled “Climate Change 2001”; the finalized report was
distributed on October 1, 2001. In it, the IPCC states that the link between climate
and human activities is clearer than before, the resultant potential warming may be
greater than previously thought, and “overall, climate change is projected to increase
threats to human health, particularly in lower income populations, predominantly3
within tropical/subtropical countries.”
For more detailed discussion, see CRS Issue Brief IB89005, Global Climate
Change, by John R. Justus and Susan R. Fletcher, and the Environmental Protection
Agency’s Global Warming site at:
[ h ttp://www.epa.gov/oar/gl obalwarming.nsf/content/index .html] .
Human health problems that may be linked to climate change are not created by
changes in climate; rather, they are problems independent of climate change that may
1 This report is about health issues related to climate change, and does not address the
underlying question of climate change itself. On that latter issue, see the CRS Issue Brief
IB89005, Global Climate Change, by John R. Justus and Susan R. Fletcher.
2 From [http://www.epa.gov/globalwarming/impacts/index.html].
3 “Climate Change 2001: Synthesis Report” Intergovernmental Panel on Climate Change.
[ h t t p : / / www.i p cc.ch/ pub/ t a r / syr / 005.ht m] .
be exacerbated or intensified by changing weather patterns.4 Most health research is
being conducted for reasons unrelated to climate change, but researchers are alert to
ways in which environmental factors affecting health may be altered by climate
This issue has drawn increasing attention during the past decade. On July 10,
1995 the United States Global Change Research Program (USGCRP, which
coordinates federal climate change research discussed below) held a seminar on
“Climate Change and Health”. This seminar included participation by the National
Institute for Environmental Health Science, and examined the roles of climate and
climate change in the emergence and re-emergence of infectious diseases in humans
Another major meeting on health and climate, the Conference on Human Health
and Global Climate Change, was held at the National Academy of Sciences on
September 11-12, 1995, was organized and conducted collaboratively by the Institute
of Medicine, the National Academy of Sciences, and the National Science and
Technology Council (NSTC), with support from several member agencies of the
NSTC. Concerns about the potential risks to human health from changes in global
climate raised at the conference led to several interagency discussions. Plans for a
follow-up study were developed within the National Research Council’s Committee
on Climate, Ecosystems, Infectious Diseases, and Human Health (CEIDH). The
CEIDH released its report “Under the Weather: Climate, Ecosystems, and Infectious
Disease” in April 2001. The report found that many infectious diseases may be
influenced by weather fluctuations and seasonal-to-interannual climate variability,
affecting their evolution and emergence through complex, sometimes causal, often
not fully understood relationships. The report recommended further research to
better understand and control the linkages among climate, diseases, epidemiological
surveillance, and public health infrastructure and measures.
The Bush Administration commissioned the National Research Council (NRC)
on May 11, 2001 to produce a report on climate change. “Climate Change Science:
An Analysis of Some Key Questions” was released in June 2001 by a special
Committee on the Science of Climate Change of the NRC. The report, prepared by
eleven of the nation’s leading climate scientists, generally concurred with the latest
conclusions of the IPCC and concluded that the climate changes observed in the past
several decades likely were due to human activities, although a significant part of the
climate changes could be from natural climate variability. It also summarized
information relating to major kinds of possible human health effects of climate
change, and identified related scientific research currently underway, in particular
under federal government auspices.
4 Climate, a longer-term phenomenon, can be considered to be the average of shorter-term
Scope of This Report
The research identified in this report includes possible human health effects of
atmospheric change generally, including health effects of stratospheric ozone
depletion that allows greater exposure to ultraviolet (UV) radiation. However, ozone
depletion is not per se usually included in climate change. While it is a major factor
in atmospheric change, its effects are more direct and do not act through changes in
climate. While the agents that deplete stratospheric ozone are themselves greenhouse
gases, ozone depletion itself is regarded as a problem separate from climate change.
In many cases, air quality and water supply and quality may be affected by
weather changes. Heavy or rapid rainfall, for example, can exceed the capacity of
local physical infrastructure to handle such rain, overflow and equipment overloads
can occur, and local water quality and supply may be adversely affected. Whether
weather changes may or may not be related to global climate change, and the
relationship of weather as mediated through these and other factors to health, is an
issue involving a complex web of interactions.5
Human Health Effects Possibly Related to
The range of human responses to temperature and other weather and climate
conditions and changes is very broad. Age, general health status, and physiological
resilience contribute to this breadth of responses. Given this breadth, predicting
human responses for climate change policy relies heavily on past observations and
on experience. The following observations are generally recognized from broad and
!Hot weather, often accompanied by air with higher concentrations
of pollutants, tends to be associated with excess hospitalizations, i.e.,
more people than would be expected are admitted to hospitals when
the weather is hot. These excess admissions are often because
people are experiencing respiratory difficulties.6
!Hot weather also tends to be associated with excess mortality, i.e.,
more people than would be expected die during spells of hot
weat her. 7
5 For a detailed discussion of both the direct and indirect relationships between health
impacts of weather and climate, and the difficulty of establishing cause and effect, see
Human Health and Global Climate Change, a report released in December 2000 by the Pew
Center on Global Climate Change, available at [http://www.pewclimate.org].
!Warmer environmental conditions are associated with excess
allergens and related substances (by enhancing the growth potential
of allergen-producing plants), and with excess cases of people with
allergic and asthmatic responses.8
!Warmer environmental conditions are associated with various excess
illnesses resulting from the enhancement of the range and life cycle
of disease-associated insects and microbial life forms and viruses;
these illness vectors may have been water, air, contact, and/or food
!Warmer conditions tend to be associated with more extreme weather
events, e.g., heavier precipitation which may result directly in health
impacts from floods.10
!Warmer conditions with heavier precipitation may result in indirect
health effects, e.g., public health may be threatened by overloaded
On the other hand, the following observations also can be based on general
!While about 1,000 people die from the cold each year (in
comparison, about 2,000 die from conditions related to heat12),
warmer conditions may lead to a reduction of deaths from the cold.
In general, cold-related deaths happen when relatively rare cold
spells occur in areas where people are accustomed to mild winters,
situations that may or may not be affected by global climate change.
Cold-related deaths, however, are less sensitive to temperature
changes than heat-related deaths (e.g., the mortality difference
between -29oC and -26oC [-20o F and -15o F] is less than that
observed between 35oC and 38oC [95o F and 100o F]).13
!Morbidity and mortality are not always observed to increase even if
more extreme weather events occur. Appropriate infrastructure
(including building codes, zoning, and sanitation systems), severe-
weather warning systems, disease surveillance and prevention
8 United States Department of State, U.S. Climate Action Report 2002 , Washington, D.C.,
May 2002, p. 107.
11 The Water Environmental Research Foundation is studying ways to design water-handling
infrastructure that will maintain desired levels of public health under varying environmental
programs, and education of professionals and the public appear to
prevent excess illnesses and deaths even in the face of more extreme
!As a whole, agriculture in the United States is technically advanced,
quick to adopt new technology, regionally diverse and adapted to a
wide range of conditions, intensively managed, and market based.
As such, as a whole, while the agricultural economy is argued by
some to appear to be of low vulnerability to climate change, local
monitoring of diverse local conditions has been recommended.15
Trends of Concern
Various trends, ranging in scale from local through national, may relate to the
possible human health effects of climate change, potentially augmenting morbidity
or mortality effects.
!The average age of Americans is going up. While 1 in 8 Americans16
was 65 years or older in 1990, 1 in 6 will be 65 or older in 2020.
With this expected aging, it is projected, will come a loss of
physiological resilience, on average. More of the population is
expected to be more susceptible to possible health effects from all17
environmental stresses, including any related to climate change.
!More Americans are and will be living in urban settings, which
generally demonstrate urban heat-island effects (higher average
temperatures than surrounding non-urban areas, owing to more heat-
generating activities and more heat-retaining urban structures) and
higher levels of air pollution. As such, more Americans are and will
be exposed to potentially augmented climate change stresses and18
potential health effects.
!Advancing therapies allow people with compromised immune
systems to live longer. The increasing number of
immunocompromised people means there may be more people with
14 United States Department of State, U.S. Climate Action Report 2002, Washington, D.C.,
May 2002, p. 109.
16 United States Department of Commerce, We the American Elderly, Washington, D.C.,
September 2001, p. 2.
17 United States Global Change Research Program, US National Assessment of the Potential
Consequences of Climate Variability and Change/Sector: Human Health, p. 441.
18 United States Department of State, U.S. Climate Action Report 2002, Washington, D.C.,
May 2002, p. 106.
greater vulnerability to possible climate-related health effects,
including those caused by water and vector borne pathogens.19
!“Poverty is a risk factor for heat related illnesses and deaths because
the poor are more likely to live in urban areas and are less likely to
be able to afford air-conditioning systems.”20 A recent rise in one
measure of poverty in the United States is argued by some to suggest
that there may be more poor people who may be more vulnerable to
possible climate-related health effects by being less able to afford
appropriate health care as well as air conditioning.21
!Using national data gathered on a regional level, one study
hypothesized that some regions or states may be more greatly
affected by possible health effects of climate change than others “not
only because they are more prone to summer weather/climate-related
diseases, but also because they contain a greater proportion of the
sensitive subpopulations in the United States.”22 Recognizing the
current shortages of dose-response data (linking climate to health
effects) and reliable modeling of future regional climates, the report
says that the current state of research is sufficient to generate the
hypothesis but not test it, which constitutes part of the ongoing need
for further research.
Human Health Effects Research
Related to Climate Change
Research on human health effects of environmental conditions that may result
from global climate change is being conducted domestically. While most of these
efforts are not focused specifically on climate change, they are examining health
conditions that could be affected by a change of climate, such as skin cancers caused
by solar radiation, mediated through changes in weather patterns and variability.
Some research may also relate to terrorism, e.g., use of a nuclear device by a terrorist
could result in increased cancer risks. Some cancer research could be useful in
countering radiation exposures whether from climate change or a nuclear device.
The multiplicity of benefits from basic research makes difficult the task of
categorizing basic research funding for climate change or other reasons.
19 United States Global Change Research Program, op. cit.
21 Madrick, Jeff. A Rise in Child Poverty Rates Is At Risk In U.S., the New York Times on
the Web, June 13, 2002. Also, United States Global Change Research Program, op. cit.
22 Longstreth, Janice. Public Health Consequences of Global Climate Change in theUnited
States — Some Regions May Suffer Disproportionately, Environmental Health Perspectives
Volume 107, Supplement 1, February 1, 1999, pp. 169-179.
National Institutes of Health (NIH)
Following are descriptions of research areas that could be related to climate
change and associated environmental conditions. Funding for the research is
summarized by agency in Table 1 below.
!National Cancer Institute is conducting research in two major
areas: 1) increased health risks associated with excessive exposure
to sunlight, including skin cancers and suppression of immune
systems; and 2) possible interactions of environmental conditions
(such as temperature and solar intensity) and pesticides and other
environmental toxicants (such as polychlorinated biphenyls).
!National Eye Institute is studying exposure to ultraviolet (UV)
radiation and cataracts, and the use of antioxidants to protect eyes
from UV damage (regardless of the source or cause of the UV
!National Institute of Environmental Health Sciences is
conducting research on the interactions of indoor and outdoor air
pollutants and respiratory disease (including ozone, acid aerosols,
particulate matter, and asthma), causes (including genetic) of
differential susceptibility to air pollutants, health consequences of
increased UV radiation, impacts on health of changes in the ranges
of insect and parasitic disease vectors, and health effects of damage
to the water supply.
!National Institute of Arthritis and Musculoskeletal and Skin
Diseases is conducting research on the effects of UV radiation on
skin and skin diseases, regardless of its source or cause.
Table 1. Climate Change Research at the National Institutes
Ce nters 2002 2003 2004 2005 estimate estimate
National 9.7 13.5 14.0 12.5 12.5 12.5
National 0.4 1.2 1.2 1.1 1.1 1.1
Source: United States Department of Health and Human Services, National Institutes of Health,
“Estimates of Funding for Various Diseases, Conditions, Research Areas,” updated February 3, 2006,
[http://www.nih.gov/news/fundingresearchareas.htm], and personal communication with NIH.
World Health Organization (WHO)23
The World Health Organization, an agency of the United Nations, was founded
in 1948 and currently has 191 Member States. The mission of WHO is “to give
worldwide guidance in the field of health, to set global standards for health, to
cooperate with governments in strengthening national health programmes, to develop
and transfer appropriate health technology, information and standards.”24 The Project
on Climate Change, Stratospheric Ozone Depletion, and Health was established
within WHO in 1997. This project works to: bring together and make available
scientific knowledge on the health effects of climate change/variability and
stratospheric ozone depletion, facilitate and disseminate information on preventive
policies, cooperate with countries to address specific climate-health problems and
23 A very useful report is by A.J. McMichael, A. Haines, R. Slooff, and S. Kovats (editors),
Climate Change and Human Health, World Health Organization, Geneva, Switzerland.
24 World Health Organization. Rapid Overview.
[ h t t p : / / www.who.i nt / a bout who/ en/ r api d.ht m] .
increase local capacity, and facilitate the coordination of research to answer the key
questions on climate and health.”25
Some of WHO’s major areas of concern and effort include the establishment of
an interagency network to effectively communicate among parties, development of
a system for monitoring health effects and for conducting assessments of national
health impacts, and development and implementation of methods for adaptation and
mitigation.26 These major areas of concern incorporate specific concerns, such as
the growing threat of spreading antibiotic resistance (malaria, for example, has
become immune to antibiotics in some countries), and funding that may be
inadequate to the task.27 Specific funding levels for United States support of WHO’s
climate-associated human health effects research were unavailable but were
characterized as “small.”28
The changing global climate likely will impact the complicated interrelated web
of plant and animal life, viruses, water, air, and land. The magnitude and beneficial
or adverse direction of the impact will depend on specific locations and economic,
political, social, and environmental conditions. Studies on the subject have produced29
myriad conclusions. Only very basic conclusions find wide agreement at present:
!The infirm, the elderly, and the poor may be disproportionately and
negatively impacted should climate change result in more severe
and/or more frequent episodes of heat waves and air pollution.
!The risks of vector- and water-borne diseases may increase with
global warming, but countries and regions with adequate sanitation,
surveillance, and public health systems may not see significant
increases in disease incidence or distribution.
!Further research is needed to better understand the complex linkages
among climate and health.
25 World Health Organization. Climate Change.
[http://www.who.it/london_confer ence/climate_change.htm] .
26 Personal communication with Bettina Menne MD, Associate Professional Officer Public
Health, WHO-European Centre for Environment and Health. [email@example.com] March 2000.
27 Antibiotic resistance a growing threat, WHO reports.
[ h t t p : / / www.cnn.com/ 2000/ HEALT H/ 06/ 12/ ant i b i o t i c .r esi s t a nce/ i ndex.ht ml ] .
28 Personal communication with Bettina Menne MD, op.cit.
29 Among others: Pew Center on Global Climate Change, Human Health and Global
Climate Change, December 2000; Commission on Geosciences, Environment, and
Resources, Under the Weather: Climate, Ecosystems, and Infectious Disease, National
Academy Press 2001; A.J. McMichael, Climate Change and Human Health, op.cit.