Title:
HEALTH, WEATHER AND OTHER IMPACTS OF GLOBAL WARMING:KRISTIE
EBI
Date:
Congressional Testimony
04-26-2007
Statement of Kristie Ebi
ESS, LLC Committee on House Select Energy Independence
and Global Warming April 26, 2007 Weather and climate are among the factors
that determine the geographic range and incidence of several major causes
of ill health, including undernutrition, which
affects 17% of the world`s
population in developing countries [FAO 2005]; diarrheal
diseases and other
conditions due to unsafe water and lack of basic sanitation, which cause
2 million deaths annually, mostly in young children [Kosek
et al. 2003];
and malaria, which causes more than a million childhood deaths annually
[WHO 2004]. The Human Health chapter in the Fourth Assessment Report of
the Intergovernmental Panel on Climate Change, for which I was a Lead Author,
concluded that climate change has begun to negatively affect human health,
and that projected climate change will increase the risks of climate-sensitive
health outcomes, particularly in lower-income populations, predominantly
within tropical/subtropical countries [IPCC WGII SPM 2007]. Weather, climate
variability, and climate change can affect health directly and indirectly.
Directly, heatwaves, floods, droughts, windstorms and
fires annually affect
millions of people and cause billions of dollars of damage. In 2003 in
people dead or missing and caused $9.73 billion in insured damages [Swiss
Re 2004]. More than 35,000 excess deaths were
attributed to the extended
heatwave in
extreme events in developing countries are substantially larger. There
is a growing body of scientific research projecting that the frequency
and intensity of extreme weather events will likely increase over the coming
decades as a consequence of climate change [Easterling
et al. 2000; Meehl
and Trebaldi 2004], suggesting that the associated
health impacts also
could increase. Indirectly, climate can affect health through alterations
in the geographic range and intensity of transmission of vector-, tick-,
and rodent-borne diseases and food- and waterborne diseases, as well as
through changes in the prevalence of diseases associated with air pollutants
and aeroallergens. Climate change could alter or disrupt natural systems,
making it possible for diseases to spread or emerge in areas where they
had been limited or had not existed, or for diseases to disappear by making
areas less hospitable to the vector or the pathogen [NRC 2001]. Climate-
induced economic dislocation and environmental decline also can affect
population health. The cause-and-effect chain from climate change to changing
patterns of health determinants and outcomes is often complex and includes
factors such as wealth, distribution of income, status of the public health
infrastructure, provision of medical care, and access to adequate nutrition,
safe water, and sanitation [Woodward et al. 1998]. Therefore, the severity
of future impacts will be determined by changes in climate as well as by
concurrent changes in nonclimatic factors and by the
adaptation measures
implemented to reduce negative impacts. It is important to note that even
if future trends decrease burdens of some climate- sensitive health outcomes,
the attributable burden due to climate change could increase. Figure 1
summarizes the relative direction, magnitude, and certainty of climate
change-related health impacts as concluded by the Human Health chapter
of the Fourth Assessment Report of the Intergovernmental Panel on Climate
Change. Heatwaves, Floods, and Droughts The impact of
an extreme weather
event is determined by the physical characteristics of the event, attributes
of the location affected, and interactions of these with human actions
and social, economic, institutional, and other systems. The health and
social burden of extreme weather events can be quite large, causing loss
of life and livelihood, infrastructure damage, population displacement,
and economic disruption (such as in Honduras and Nicaragua following hurricane
Mitch in 1998, and hurricane Katrina). Climate change is projected to increase
the intensity and frequency of extreme weather events in many regions [IPCC
SPM WGI 2007]. Heatwaves affect human health via heat
stress, heatstroke,
and death [Kilbourne 1997], as well as exacerbations
of underlying conditions
that can lead to an increase in all-cause mortality [Kovats
and Koppe 2005].
The frequency and intensity of heatwaves [Meehl and Tebaldi 2004] and
heat-related
deaths are projected to increase with climate change [Keatinge
et al. 2002;
Dessai 2003; McMichael et
al. 2003; Hayhoe et al. 2004]. For example, the
annual number of heatwave days, the length of the heatwave season, and
heat-related mortality were projected for four cities in
et al. 2004]. By the 2080s, under two climate scenarios, the number of
heatwave days in Los Angeles were projected to
increase from 4-fold to
6-8 fold over the 1961- 90 baseline. Annual heat-related deaths in
Angeles
1,182 under different scenarios. The length of the heatwave
season in
was projected to increase from 5-13 weeks. Projections have not considered
changes in the frequency or intensity of severe heatwaves,
such as occurred
in 2003 in
where increasing temperatures could affect human and agricultural productivity.
The adverse health consequences of flooding and windstorms can be complex
and far-reaching [Ahern et al. 2005; Hajat et al.
2003]. Adverse health
impacts include the physical health effects experienced during the event
or clean-up process, or from effects brought about by damage to infrastructure,
including population displacement. The physical effects largely manifest
themselves within weeks or months following the event, and can be direct
(such as injuries) and indirect (such as water and food shortages and increased
rates of vector-borne and other diseases). Extreme weather events are also
associated with mental health effects resulting from the experience of
the event or from the recovery process. These psychological effects tend
to be much longer lasting and can be worse than the direct physical effects
[Ahern et al. 2005; Hajat et al. 2003]. The effects
of drought on health
include malnutrition (protein- energy malnutrition and/or micronutrient
deficiencies), infectious diseases, and respiratory diseases [Menne and
Bertollini 2000]. In addition, malnutrition increases
the risk of dying
from an infectious disease. The loss of livelihoods due to drought is a
major trigger for population movements, which can cause additional disease
burdens. Parry et al. [2004] projected that the world will have sufficient
food to feed everyone up to the end of the 21st century; however, this
assumed that people in low-income countries, where climate change impacts
are predominantly negative, would have access to food produced in temperate
countries. Attribution of the some portion of the burden of injuries, illnesses,
and deaths due to floods, windstorms, and droughts to climate change is
complex because of the multiple determinants of disease. Although data
are limited, malnutrition associated with drought and flooding may be one
of the most important consequences of climate change due to the large number
of people that may be affected. For example, one study projected that climate
change could increase the percentage of the Malian population at risk of
hunger from 34% to 64 - 72% by the 2050s, although this could be reduced
by implementation of a range of adaptive strategies [Butt et al. 2005].
Malaria and Other Infectious Diseases Climate is a primary determinant
of whether a particular location has environmental conditions suitable
for the transmission of several vector-, rodent-, and tick-borne diseases,
including malaria, dengue, cholera, meningitis, Japanese encephalitis,
St. Louis encephalitis, West Nile virus, tick-borne encephalitis, Rift
Valley Fever, schistosomiasis, and leishmaniasis. A change in temperature
may hinder or enhance vector and parasite development and survival, thus
lengthening or shortening the season during which vectors and parasites
can survive. Small changes in temperature or precipitation may cause previously
inhospitable altitudes or ecosystems to become conducive to disease transmission
(or cause currently hospitable conditions to become inhospitable). While
climate is an important driver of malaria and other diseases, it is not
the only one. The many determinants of infectious diseases often form an
interconnected web with feedbacks between transmission dynamics and other
factors [Chan et al. 1999]. For example, the socioeconomic and biological
drivers of malaria include drug and pesticide resistance, deterioration
of health care, deterioration of public health infrastructure (including
vector control efforts), demographic change, and changes in land use. Malaria
is a complex disease to model, and current models have not completely
parameterized
the key factors that influence transmission. Given this limitation, models
suggest that, in
and contractions of the geographic area suitable for transmission of stable
Plasmodium falciparum malaria, with expansion
projected to be larger than
contraction [Ebi et al. 2005; Tanser
et al. 2003; Thomas et al. 2004; van
Leishout et al. 2004]. These projections are
consistent with experiences
with malaria control officers in the field. Some projections suggest that
the season of transmission may be extended, which may be as important as
geographical expansion. Several food- and waterborne diseases are climate
sensitive, suggesting that climate change could affect their incidence
and distribution. For example, studies report an approximately linear
association
between temperature and salmonellosis, a common form
of food-poisoning
[e.g. D`Souza et al. 2004; Kovats
et al. 2004; Fleury et al. 2006]. Water
and foodborne diseases continue to cause significant
morbidity in the
Annually, there are approximately 1,330 food-related disease outbreaks
[Lynch et al. 2006], 34 outbreaks from recreational water (2004), and 30
outbreaks from drinking water (2004) [Dziuban et al.
2006, Liang et al.
2006]. For outbreaks of foodborne disease with known
causes, Salmonella
accounted for 55% and viruses accounted for 33% [Lynch et al. 2006]. Water-
and foodborne disease are highly underreported; using
a combination of
underreporting estimates, passive and active surveillance data, and hospital
discharge data, Mead et al. (1999) estimated that over 210 million cases
of gastroenteritis annually in the U.S., including over 900,000
hospitalizations
and over 6,000 deaths. Approximately 39 million of the cases can be attributed
to a specific pathogen and about 14 million are transmitted by food. The
causes differ somewhat from those reported for outbreaks, with the highest
frequency of illness caused by viruses (67%; primarily noroviruses),
followed
by bacteria (30%; primarily Campylobacter and Salmonella) and parasites
(3%; primarily Giardia and Cryptosporidium). Children
ages 1-4 and older
adults (>80 years) each make up more than 25% of hospitalizations involving
gastroenteritis, but older adults contributed to 85% of the associated
deaths [Gangarosa et al. 1992]. Clearly, as the
economic and public health burden of diarrheal
disease will increase proportionally
without appropriate interventions. Air Pollutants There is extensive literature
documenting the adverse health impacts of exposure to elevated concentrations
of air pollution, especially particulates with aerodynamic diameters under
10 and 2.5 ?m, ozone, sulphur dioxide, nitrogen
dioxide, carbon monoxide,
and lead. In 2000, there were 0.8 million deaths from respiratory problems,
lung disease, and cancer that were attributed to urban air pollution, with
the largest burden in developing countries in the Western Pacific region
and South East Asia [WHO 2002]. In addition, there were 1.6 million deaths
attributed to indoor air pollution caused by burning biomass fuels. Air
pollution concentrations are the result of interactions among local weather
patterns, atmospheric circulation features, wind, topography, human responses
to weather changes (i.e. the onset of cold or warm spells may increase
heating and cooling needs, and, therefore, an increase in electricity
generation),
and other factors. Climate change could affect local to regional air quality
directly through changes in chemical reaction rates, boundary layer heights
that affect vertical mixing of pollutants, and changes in synoptic airflow
patterns that govern pollutant transport. Indirect effects could result
from increasing or decreasing anthropogenic emissions via changes in human
behavior, or from altering the levels of biogenic emissions because of
higher temperatures and land cover change. Establishing the scale (local,
regional, global) and direction of change (improvements or deterioration)
of air quality is challenging [Bernard et al. 2001]. More is known about
the potential impact of climate change on ground-level ozone than on other
air pollutants. Changes in concentrations of ground-level ozone driven
by scenarios of future emissions and /or weather patterns have been projected
for Europe and North America [Stevenson et al. 2000; Derwent
et al. 2001;
Johnson et al. 2001; Taha 2001; Hogrefe
et al. 2004]. Future emissions
are, of course, uncertain, and depend on assumptions of population growth,
economic development, and energy use [Syri et al.
2002; Webster et al.
2002]. Based on projections of county-level pollutant concentrations, summer
ozone-related mortality was projected to increase by 4% in the
area by the 2050s based on climatic changes alone [Knowlton et al. 2004].
Increases in background ozone levels could affect the ability of regions
to achieve air quality targets. Global Assessments of the Health Impacts
of Climate Change Hitz and Smith [2004] reviewed the
literature on the
projected health impacts of climate change and concluded that health risks
are more likely to increase than decrease with increasing global mean surface
temperature, particularly in low latitude countries. In addition to greater
vulnerability to climate, these countries have some of the highest populations,
tend to be less developed, and generally have poorer public health
infrastructure,
likely leading to greater damages. In the most comprehensive evaluation
of the burden of disease due to climate change, McMichael
et al. [2004]
used a comparative risk assessment approach as part of the Global Burden
of Disease study to project the total health burden attributed to climate
change between 2000 and 2030 and to project how much of this burden could
be avoided by stabilizing greenhouse gas emissions. Health outcomes were
analyzed by region to better understand where current and projected future
disease burdens are highest and to identify the outcomes that contribute
to the largest share of the total burden. Limitations of the approach include
the limited number of quantitative models that estimate the likely impacts
of climate change on health and the limited geographic range of many of
the models. The health outcomes included in the analysis were chosen based
on sensitivity to climate variation, predicted future importance, and
availability
of quantitative global models (or feasibility of constructing them) [McMichael
et al., 2004]. Specific health outcomes included were episodes of diarrheal
disease, cases of Plasmodium falciparum malaria,
fatal unintentional injuries
in coastal floods and inland floods/landslides, and non-availability of
recommended daily calorie intake (as an indicator for the prevalence of
malnutrition). Inclusion of a limited number of health outcomes suggests
that the estimated impacts are likely to be an underestimate of the true
health impacts. In the year 2000, climate change was estimated to have
caused the loss of more than 150,000 lives (0.3% of worldwide deaths) and
5,500,000 Disability Adjusted Life Years (DALYs)
(0.4% worldwide), with
malnutrition accounting for approximately 50% of these deaths and DALYs
[Ezzati et al. 2002; McMichael
et al. 2004; Patz et al. 2005]; see Figure
2. These estimates relate to a period when limited climate change had occurred,
suggesting that future studies are likely to estimate larger health burdens
due to climate change. Figure 2: Current Health Burden due to Climate Change
The projected relative risks attributable to climate change in 2030 vary
by health outcome and region, and are largely negative, with the majority
of the projected disease burden due to increases in diarrheal
disease and
malnutrition, primarily in low- income populations already experiencing
a large burden of disease [McMichael et al. 2004].
Absolute disease burdens
depend on assumptions of population growth, future baseline disease incidence,
and the extent of adaptation. Particularly Vulnerable Populations Vulnerability
to climate change will vary between and within populations. Vulnerability
to the health impacts of climate change depends on the region of interest,
the health outcome, and population characteristics, including human,
institutional,
social, and economic capacity, distribution of income, provision of medical
care, and access to adequate nutrition, safe water, and sanitation. In
general, the most vulnerable include slum dwellers and homeless people
in large urban areas, particularly in low-income countries, those living
in water-stressed regions, settlements in coastal and low-lying areas,
and populations highly dependent on natural resources. However, as shown
during the 2003 heat event in
to cope with the projected increase in the intensity and frequency of extreme
weather events. Adaptation and Mitigation Climate change will make more
difficult the control of climate- sensitive health determinants and outcomes.
Therefore, health policies need to explicitly incorporate climate-related
risks in order to maintain current levels of control [Ebi
et al. 2006].
In most cases, the primary response will be to enhance current health risk
management activities. Nearly all of the health determinants and outcomes
that are projected to increase with climate change are problems today.
In some cases, programs will need to be implemented in new regions; in
others, climate change may reduce current infectious disease burdens. The
degree to which programs and measures will need to be augmented to address
the additional pressures due to climate change will depend on factors such
as the current burden of climate-sensitive diseases, the effectiveness
of current interventions, projections of where, when, and how the burden
of disease could change with changes in climate and climate variability,
the feasibility of implementing additional cost-effective interventions,
other stressors that could increase or decrease resilience to impacts,
and the social, economic, and political context within which interventions
are implemented [Ebi et al. 2006]. Although there are
uncertainties about
future climate change, failure to invest in adaptation may leave communities
and nations poorly prepared and increase the probability of severe adverse
consequences [Haines et al. 2006]. Adaptation policies and measures need
to consider how to effectively reduce climate-related risks in the context
of sustainable development, considering projected demographic, economic,
institutional, technologic, and other changes. Because fossil fuel combustion
is a source of urban air pollutants and greenhouse gases, policies to reduce
GHG emissions can have health benefits in the near- and long-term. There
are potentially synergies in reducing GHG and improving population health
via sustainable transport systems that make more use of public transport,
walking, and cycling, especially in rapidly developing countries such as
impact assessments should be conducted to evaluate positive and negative
health impacts. The current burden of climate-sensitive diseases suggests
that adaptation and mitigation policies and measures need to be implemented
soon to reduce the projected risks due to climate change.
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