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Climate change-related disturbances of physical systems (e.g., weather patterns, sea level, water supplies) and ecosystems (e.g., agro-ecosystems, disease-vector habitats) could pose risks to the health of human populations. Some health impacts would occur via direct pathways (e.g., death from heat waves and other extreme weather events, such as hurricanes); others would occur via indirect pathways (e.g., changes in the geographical range of vector-borne diseases). Researchers generally agree that most of the impacts of climate change on human health are likely to be adverse. The vulnerability of populations to such threats will depend on many factors, including present health status, quality of available health care services and associated infrastructure, and availability of financial and technical resources (McMichael, 1993).
Should global warming increase the frequency and/or severity of extreme weather events such as droughts, floods, landslides, and tropical cyclones, it is likely that more deaths, injuries, infectious disease cases, and psychological disorders could result (McMichael and Martens, 1995; IPCC 1996, WG II, Section 18.2.2). Elevated global mean temperatures also could lead to a greater frequency of heat waves-and consequently a higher incidence of related illness (predominantly cardiorespiratory) and mortality. Inevitably, the most vulnerable countries will be those with reduced capacity to respond to or mitigate these threats. Because of their present social and economic circumstances, many small islands fall into this category.
The transmission of many infectious diseases is affected by climatic factors.
Vector-borne diseases such as malaria, dengue, and yellow fever are sensitive
to factors such as temperature, rainfall, and humidity. Climate change could
increase the geographical range of disease agents; changes in the life-cycle
dynamic of vectors and infective agents, in aggregate, could result in more
efficient transmission of many vector-borne diseases (McMichael et al., 1996).
Mathematical models project that an additional 50-80 million cases of malaria
would result from a mean temperature increase of 3.0�C (Martens et al., 1995).
Although most of this projected increase is expected to be in temperate-zone
countries, some increase in the tropics-the latitudinal zone in which the majority
of small islands and other developing countries are located-cannot be ruled
out (see Table 9-3). Moreover, even a marginal increase
in the incidence of disease would place great stress on the public health systems
of many small islands, where these facilities often are not well developed.
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