The effects of changing weather on public health

Many diseases are influenced by weather conditions or display strong season ality, suggestive of a possible climatic contribution. Projections of futur e climate change have, therefore, compelled health scientists to re-examine weather/disease relationships There are three projected physical consequen ces of climate change: temperature rise, sea level rise, and extremes in th e hydrologic cycle. This century, the Earth has warmed by about 0.5 degrees centigrade, and the mid-range estimates of future temperature change and s ea level rise are 2.0 degrees centigrade and 49 centimeters, respectively, by the year 2100. Extreme weather variability associated with climate chang e may especially add an important new stress to developing nations that are already vulnerable as a result of environmental degradation, resource depl etion, overpopulation, or location (e.g. low-lying coastal deltas). The reg ional impacts of climate change will vary widely depending on existing popu lation vulnerability. Health outcomes of climate change can be grouped into those of: (a) direct physical consequences, e.g, heat mortality or drownin g; (b) physical/chemical sequelae, e.g. atmospheric transport and formation of air pollutants; (c) physical/biological consequences, e.g. response of vector- and waterborne diseases, and food production; and (d) sociodemograp hic impacts, e.g. climate or environmentally induced migration or populatio n dislocation. Better understanding of the linkages between climate variabi lity as a determinant of disease will be important, among other key factors , in constructing predictive models to guide public health prevention.