Global Ecological Change
and Human Health
Jonathan A. Patz
Nathan D. Wolfe
Environmental changes and ecological disturbances, due to both natural phenomena and human activities, have exerted and can be expected to continue to exert a strong influence on the incidence, proliferation, and emergence of disease. This chapter focuses on both near-term and sequential effects that environmental factors and their changes have on ecosystems and, consequently, on human health. The types of environmental conditions and changes that contribute to proliferation of disease are discussed, as well as the effects on health of changes in climate and land use, especially deforestation and its many sequelae: logging, road building, hunting, human settlement patterns, agricultural and commercial development, and formation of water bodies (including water control systems. An illustrative example of an illness (malaria) resulting from ecological change is also presented.
Climate consists of variations in interactions among components of the climate system, including the atmosphere, oceans, sea ice, and land features. Changes in any of the climate system components, whether natural or from external (humaninduced) forcing, can cause climatic variation and change. Change in climate can result in increased temperature, rise in sea level, extremes in the hydrologic cycle (Kattenberg et al. 1996), and potentially, accelerated ozone depletion (Shindell et al. 1998; Kirk-Davidoff et al. 1999). Small changes in the mean climate can