The sectors treated in the preceding seven chapters refer to technology options for mitigating climate change and for adapting to the impacts of climate change. The consideration of human health is largely limited to health impacts and benefits that arise from: (i) climate change, (ii) mitigation, and (iii) adaptation. The formal health sector is not substantively involved in the reduction of greenhouse gas emissions - other than incidentally via participation in society-wide improved energy efficiency (hospital building design, institutional energy-use policies, etc.), and by promoting alternative energy-saving systems of transport and mobility to increase physical activity levels. Nevertheless, by providing reproductive health and family planning services (in concert with education and social liberalisation), the health sector contributes to climate change mitigation via reductions in birth rates. Human population size is one of the prime determinants of total greenhouse gas emissions (Engelman, 1998).
Long-term changes in world climate would affect the foundations of public health - sufficient food, safe and adequate drinking water, secure community settlement and family shelter, and the environmental and social control of various infectious diseases. Currently, malnutrition is a major factor in 11.7% of deaths worldwide (i.e., 5.8 million deaths every year) and accounts for an estimated 15.9% of total DALYs lost (Disability-Adjusted Life Years - a composite measure of the burden of ill health) (Murray and Lopez, 1996). Climate change is likely to make food and water supplies more uncertain in various regions, thereby increasing the risk to health for hundreds of millions of vulnerable persons, particularly in sub-Saharan Africa.
Despite the fundamental long-term dependence of human health upon the sustainability of physical and ecological systems, this dependency is not yet well appreciated by the general public and policymakers. Ecosystem services (i.e., processes maintained by the natural ecosystems) are essential for the support of human health and well-being. Natural processes that are maintained at levels adequate for human health include: the chemical composition of the atmosphere; decontamination of rivers and oceans; fertility of soils; and the availability of genetic resources. Climate change, by contributing either directly or indirectly to the impairment of natural unmanaged ecosystems can affect human health. This damage can occur via changes in species composition occurring in response to new climatic conditions. Climate change may also cause an increase in forest fires due to drought; salinisation of water sources; increased soil erosion due to heavy rainfall; and the reduction of GHG sinks due to reductions in vegetation cover.
Climate change, by stretching limited social resources across a broad range of additional health and other problems, could also impair existing public health programmes. Enhancement of the public health and nutrition interventions that are cornerstones of development (e.g., food and nutrition policies, environmental management, disease surveillance, and access to high quality health services) is an important way to reduce vulnerability to the health impacts of climate change. Whatever the economic or developmental level of the population in question, adaptations that also meet more general policy needs and specific existing local needs should generally be favoured, for reasons of cost-effectiveness, equity (especially between present and future generations), and political acceptability (McMichael and Hales, 1997).
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