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					                                                                                                                                                                                                           The Medical and Public Health Impacts of Global Warming
                                                                                                            A F A c T S H e e T F R o M PH y S I c I A n S F o R S o c I A l R e S P o n S I b I l I T y
          The Medical and Public Health Impacts of Global Warming

A Warming World                                       stress, the body’s ability to shed heat through
    As scientific evidence continues to mount         increased blood circulation and perspiration,
that the earth’s climate is rapidly changing, it      and thus its ability to maintain temperature bal-
is clear that global warming is no longer just a      ance, is lost.6 In such cases, death can result.
prediction.                                              The 2003 European heat waves resulted in a
    Rising oceans, stronger hurricanes, pro-          surge of heat-related deaths. Across the United
longed droughts, and more intense heat waves          Kingdom, France, Italy, the Netherlands, Portu-
are signs of the already discernable impacts that     gal, and Spain, the heat waves that occurred dur-
global warming is having worldwide. Global            ing the summer of 2003 are estimated to have
average surface temperatures have increased by        caused at least 22,000 excess deaths, with some
about one degree Fahrenheit since the begin-          arguing that this figure could be revised upward
ning of the 20th century,1 and the five hottest       by as much as an astounding 50–100 percent.7
years on record have all occurred within the last        In the United States, a seven-day (July14–
decade.2 With the atmospheric concentration of        20) heat wave in Chicago during the summer
carbon dioxide (CO2) now higher than at any           of 1995 resulted in 485 heat-related deaths.8 In
point in the last 420,000 years, widespread con-      total, 739 excess deaths were reported during
sensus within the scientific community points         this period, representing a 147 percent increase
to the burning of fossil fuels as the primary         above baseline levels.8
cause of this warming of the planet.3 Unless             These figures demonstrate the potentially
emissions of heat-trapping greenhouse gases           devastating impact that could result from an
are reduced, temperatures will increase by an         increase in heat wave frequency and intensity.
additional 2.5 to 10.4 degrees Fahrenheit during      Though heat waves normally affect broad geo-
the next 100 years—a rate likely to be without        graphic regions and resident populations, certain
precedent in the last 10,000 years.1                  groups are particularly vulnerable. The very old
    Beyond the serious and potentially irrevers-      and the very young tend to have reduced heat-
ible impacts on physical and biological systems,4     regulating mechanisms and are at increased
a growing body of research also suggests that         risk.6 The poor, the socially isolated, and those
global warming will adversely affect public           already suffering from chronic illness also are
health in a number of important ways.                 likely to be disproportionately affected by an
                                                      increase in heat wave frequency and severity.6
Heat-Related Illness
   Climate models predict that North American
                                                      Air Pollution-Related Health Impacts
heat waves will increase in intensity, frequency,         While both air pollutant emissions and
and duration as global mean temperatures rise         ambient pollutant concentrations have generally
over the course of this century.5 Under this          fallen since passage of the 1970 Clean Air Act,
scenario, the many health problems associ-            as recently as 2002 approximately 146 million
ated with exposure to extreme and prolonged           people in the United States lived in counties that
heat—heat cramps, heat syncope (fainting),            did not meet air quality standards for at least one
heat exhaustion, and heatstroke6—will become          regulated pollutant.9 Exposure to air pollution can
increasingly common. Heat acclimatization is          aggravate chronic respiratory and cardiovascular
possible, but in cases of extreme or chronic heat     disease, damage lung tissue, lead to premature


                    P h y s i c i a n s f o r S o c i a l Re s p o n s i b i l i t y
    death, and may even contribute to cancer.10              additional benefit of reducing the adverse health
Global warming may exacerbate these problems                 effects associated with a range of air pollutants.
by affecting the concentration, distribution, and               There also is growing evidence that rising
type of both manmade and natural air pollut-                 global mean temperatures are impacting both
ants.10 Ozone levels, for example, are likely to             the timing and abundance of airborne aller-
increase because higher temperatures accelerate              gens, especially pollen.14
the rate at which ground-level ozone (the main                  In recent decades, spring flowering, and thus
component of smog) is formed.10 While long-                  the allergenic pollen season, has advanced at
term exposure to ozone is linked to the develop-             a rate of nearly a day per year.15 In Europe,
ment and exacerbation of chronic lung diseases,              spring events such as leaf unfolding advanced
even short-term exposure to relatively low ozone             by six days, while autumn events such as leaf
concentrations can cause lung inflammation,                  coloring have been delayed by nearly five days
acutely decreased lung function, and respiratory             in the last 35 years.16 Experimental studies have
impairment.10 A 2004 study using global warm-                demonstrated significant increases in pollen
ing and air quality models in the 31-county New              production resulting from exposure to in-
York metropolitan region projected a median                  creased CO2 concentrations, while examination
increase of ozone-related acute mortality across             of recent trends have linked elevated pollen
the region of 4.5 percent by the 2050s.11                    levels to increases in temperature.14 Addition-
    Although increasing atmospheric CO2                      ally, some studies suggest stronger allergenicity
concentrations have no known direct adverse                  of pollen from trees grown at increased tem-
health effects, other byproducts of fossil fuel              peratures.17 Patz, et al. warn of the potential
combustion, including airborne particulate                   public health consequences of these changes:
matter (PM), sulfur oxides (SOx), and nitrogen               “climate change may adversely impact the oc-
oxides (NOx), are associated with a number of                currence and severity of asthma, the most com-
well-established health risks.12 Consequently, a             mon chronic disease of childhood, and affect
continued rise in CO2 emissions would be mir-                the timing or duration of seasonal allergies such
rored by a rise in the harmful effects of these              as hay fever.”14 Combined with the observed
combustion byproducts.                                       doubling of pediatric asthma prevalence within
     In recognizing the link between CO2 emis-               the past twenty years,18 children’s physiologi-
sions and PM pollution, Cifuentes et al. estimat-            cal and behavioral susceptibility to air pollution
ed that adoption of existing, readily acquirable             increases their risk of being adversely affected
greenhouse gas mitigation technologies would                 by changes in the concentration and distribu-
reduce PM concentrations by 10 percent, thus                 tion of pollutants.19
avoiding 64,000 premature deaths and 65,000
chronic bronchitis cases through 2020 in four
cities alone—New York City, USA; Santiago,
                                                             Infectious Disease
Chile; Mexico City, Mexico; and São Paulo,                      Since 1976 the world has witnessed not only
Brazil.13 These studies demonstrate that actions             the emergence of 30 diseases previously un-
aimed at mitigating the atmospheric accumula-                known to medicine, but also the resurgence of
tion of greenhouse gases would have the                      older diseases such as malaria and cholera, and


                                      Forebodings from the Gulf coast
The devastation produced by Hurricanes Katrina and          hurricanes… has increased markedly since the mid-
Rita along the Alabama, Mississippi, and Louisiana          1970s,” warning that “future warming may lead to an
coasts has given new urgency to the threats posed by        upward trend in tropical cyclone destructive potential.”
global warming. Although Hurricane Katrina cannot be
specifically attributed to global warming, recent trends    Already, more than 1,200 deaths have been reported as a
point to a shift toward more intense storms.                result of Katrina.42 Public health and rescue workers also
                                                            have documented numerous cases of respiratory and di-
As tropical ocean sea surface temperatures (SSTs)           arrheal disease among evacuees and rescue workers. The
continue to rise—SSTs increased 0.5 degrees Celsius         long-term public health effects of the storm, however,
during the last 35 years40—warmer ocean temperatures        remain uncertain though considerable. Of particular
will increase the total energy available to amplify storm   concern are the health threats associated with exposure
intensity. According to a study published in the journal    to molds in flood damaged structures and the risk posed
Science, during the past 35 years the number of hurri-      by the toxic residues left behind from the flooding of
canes reaching categories 4 and 5 has nearly doubled in     chemical facilities and oil refineries along the 100 mile
both number and proportion.40 Other investigators have      stretch between Baton Rouge and New Orleans known
concluded that “the potential destructiveness of            as “Cancer Alley.”
   the redistribution of others, including West       years.25 While increasing global temperatures
Nile virus.15 While not all of these changes in in-   will create heavier precipitation events in some
fectious disease transmission patterns are related    regions, acceleration of land-surface
to global warming, Paul Epstein, MD, of Harvard       drying will also mean more frequent, more
Medical School’s Center for Health and the Glob-      severe drought in others.25
al Environment has warned that “a warming and             Death and injury are the direct health im-
unstable climate is playing an ever-increasing        pacts most commonly associated with extreme
role in driving this global emergence, resurgence,    weather events. However, the environmental
and redistribution of infectious diseases.”20 Fur-    hazards left behind by natural disasters such as
thermore, in a 2003 report on climate change          floods and hurricanes can also have a number
and human health, the World Health Organiza-          of serious secondary health effects.
tion (WHO) concluded that “changes in infec-              Water quality would be jeopardized by
tious disease transmission patterns are a likely      increased heavy rainfalls, especially if preceded
major consequence of climate change.”21               by drought, as surface waters became polluted
   Vector-borne diseases result from infections       by runoff carrying human and animal wastes,
transmitted to humans primarily by blood feeding      pesticides, fertilizers, and other pollutants.29
arthropods such as mosquitoes, ticks, and fleas.22    In the past, outbreaks of water-borne diseases,
Most vector-borne diseases exhibit a distinct         such as Cryptosporidium and Escherichia coli,
seasonal pattern, with weather variables such         have been linked to heavy rainfall events.14,30
as temperature and rainfall                                                  An analysis of 548 gastro-
affecting both the vectors and                                               intestinal outbreaks that
the disease-causing pathogens                                                occurred in the United
they transmit.23 Mosquitoes,                                                 States between 1948 and
for example, are very sensi-                                                 1994 showed that 68 per-
tive to temperature changes.24                                               cent of cases were preced-
Higher temperature increases                                                 ed by very heavy rainfall.31
their rate of reproduction, the                                              Threats to water quality
number of blood meals they                                                   from increased precipita-
take, prolongs their breed-                                                  tion would be compound-
ing season, and shortens the                                                 ed by rising temperatures,
maturation period for the                                                    which promote the growth
pathogens they carry.24 Rising                                               of disease-causing bacteria.
global temperatures could                                                        In the ocean, the combi-
also result in the expansion of vector ranges into    nation of rising surface water temperatures and
areas with previously unexposed populations.14        increased nutrient loading from rivers carrying
The 1999 outbreak of West Nile virus (WNV) in         agricultural runoff may contribute to increased
New York in which seven people died,20 and the        harmful blooms of algal species capable of pro-
subsequent expansion of the disease in the            ducing biotoxins.29 The consumption of fish and
summer of 2002, when 230 animal species were          shellfish contaminated by these toxins can result
infected and cases of human or animal WNV             in neurological damage, respiratory irritation,
were reported in 44 states and the District of        skin irritations, and gastrointestinal illness.32
Columbia,24 exemplify what may occur more                 Water quantity also may become an issue as
regularly as global warming progresses.               a result of global warming. Droughts, decreased
                                                      winter snow-packs, earlier snowmelt, and a
extreme Weather events and                            shift to less frequent but more intense precipi-
Water-Related Health Impacts                          tation events could all put a strain on freshwa-
                                                      ter resources.29 As water supplies decline, con-
   Evidence indicates that extreme weather            centrations of human waste, animal waste, and
events such as heavy precipitation, floods,           other pollutants increase while stagnant waters
droughts, and hurricanes have increased in            provide breeding ground for disease vectors.33,34
frequency, intensity, and duration over the past      Poor, developing nations in southern and west
century1,25,26,27 and climate models predict that     Africa and in the Middle East are at particular
this trend will continue as global warming con-       risk to increased water stress and may experi-
tinues.4 Even if rain becomes less frequent, many     ence a rise in the incidence of water-related
areas throughout the United States will experi-       diseases as people are forced to rely on increas-
ence heavier downpours.28 The annual number           ingly contaminated sources of fresh water for
of days with precipitation exceeding two to four      all of their daily needs—drinking, cooking,
inches has already increased in the past 100          bathing, and irrigation.30
                                Addressing Global Warming:                           total electricity generation of the entire U.S.39
                                                                                     Solar energy is another renewable energy source
                                A Public Health Imperative                           capable of making a significant contribution to
                                    The evidence base for global warming             meeting U.S. energy needs. While the current
                                has grown stronger since the United Nations          economics of solar energy are constrained, costs
                                Intergovernmental Panel on Climate Change            have steadily fallen in the past 20 years. Ad-
                                (IPCC) released its first scientific assessment of   ditionally, as the materials to construct solar
                                global warming. The World Health Organization        panels become cheaper and more efficient, as
                                (WHO) estimates more than 150,000 deaths             production methods improve, and as installa-
                                and approximately 5 million ‘disability-adjusted     tion becomes easier, solar energy is expected
                                life years’ (DALYs) annually as a result of in-      to become cost-competitive with conventional
                                creasing incidences of disease and malnutrition      electricity production in the near future. Also
                                caused by global warming.35 The public health        holding enormous potential for renewable
                                impacts are expected to get worse, with climate      energy production is the harnessing of both
                                models projecting a doubling of climate-linked       geothermal heat energy and ocean tides and
                                disease burden by the year 2030 without              currents for electricity generation.
                                regulatory action.35                                     Automobiles are the second largest source of
                                    With new data indicating that sea ice loss       U.S. greenhouse gas emissions.38 Thus, a signifi-
                                in the Arctic and Antarctic is accelerating and      cant increase in the fuel economy of cars and
                                climate experts now warning that the Earth may       trucks is another essential component of any
                                be fast approaching a climate change tipping         strategy to curb global warming. Fortunately,
                                point, it is clear that we can no longer afford      hybrid engines, flex-fuel vehicles capable of
                                to delay action. To stabilize the earth’s climate    running on ethanol, and biodiesel engines are
                                and avoid the most serious public health and         all gaining in popularity and commanding an
                                environmental impacts, we must reduce our            increasing share of the automotive market.
                                greenhouse gas emissions by 80 percent below         Increased automotive efficiency not only helps to
                                1990 levels.36 This can be achieved by develop-      slow global warming, but also reduces the emis-
Physicians                      ing new, cleaner, and more efficient ways of         sion of harmful air pollution, all while saving
for social                      producing energy, transportation, and goods.         consumers money at the gas pump. As a result of
resPonsibility                      The fastest and most affordable way to curb      increased purchases of minivans, pickup trucks,
                                greenhouse gas emissions is to increase energy       and SUVs, the current average fuel economy of
1875 Connecticut Ave., NW
                                efficiency. Replacing older home appliances          America’s passenger vehicle fleet is at its low-
Suite 1012
Washington, DC 20009            such as refrigerators and washing machines           est point since the early 1980s and is far behind
                                with more efficient models; improving heat-          that of the European Union, Japan, and China.
(202) 667-4260                  ing and cooling systems; better insulating both      Existing technology is capable of nearly doubling
Fax (202) 667-4201              commercial and residential buildings; and re-        the average fuel economy of America’s cars, and
Web www.psr.org                 placing old lighting systems with new advanced       even more significant improvements are pos-
                                lighting systems that use compact fluorescent        sible in the near future as existing technologies
For more information, contact   or LED bulbs—all these actions can drastically       mature and as new technologies such as fuel
Will Callaway                   reduce energy use without having to sacrifice        cells enter the market. By providing the appro-
Legislative Director            functionality or comfort. In fact, Amory Lovins      priate incentives to both auto manufacturers and
E-mail wcallaway@psr.org        of the Rocky Mountain Institute estimates that       consumers, policymakers can ensure that these
                                75 percent of total electricity consumption in       technologies continue to grow in market share
                                the U.S. could be displaced by more widespread       and can lessen America’s need for oil while dras-
                                use of the best electricity-saving technologies.37   tically reducing the transportation fuel sector’s
                                    Because the electric power industry is the       contribution to global warming.
                                single largest source of greenhouse gas emis-            Though the task before us is formidable, we
                                sions in the U.S.,38 the generation of electricity   already possess the scientific, technical, and
                                using renewable energy technologies holds great      industrial know-how to greatly reduce global
                                potential for drastically reducing global warming    warming pollution. Scientists warn, however,
                                pollution. Wind energy already is cost-competi-      that the window of opportunity is closing quick-
                                tive with new coal and gas-fired power plants,       ly and we must begin to curb global warming
                                and the U.S. has tremendous potential for            emissions within the next ten years to prevent
US Affiliate of International   generating wind energy. In twelve states alone       the worst impacts from occurring. The time for
Physicians for the Prevention   (North Dakota, Texas, Kansas, South Dakota,          action to stop global warming is NOW!
of Nuclear War                  Montana, Nebraska, Wyoming, Oklahoma, Min-              For all references, please visit the Publications and
                                nesota, Iowa, Colorado, and New Mexico), wind        Resources page of the PSR website at http://www.psr.
                                turbines could produce as much as 2.6 times the      org/site/PageServer?pagename=enviro_resources.

				
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