models predict 1 to 3.5 degrees C warming over the next 100 years, which is a faster change than has occurred anytime in the last 10,000 years. Sea level rise and greater extremes of precipitation and drought are likely results of this warming. 2

These kinds of climatic changes can have dramatic impacts on ecosystems, altering the distribution of forests, water resources, and animal species, and the productivity of agricultural systems. Such changes, in turn, will have important consequences for human well-being, because we depend on healthy ecosystems for so many essential goods and services, such as food, fiber, medicine, soil protection, water purification, flood control, and nutrient cycling. Climate change also could have direct deleterious impacts on human health, due to increases in vector borne diseases in the tropics and subtropics, and increased episodes of heat stress and urban smog. 3

Watson emphasized that the sensitivity of different systems depends on both the rate and magnitude of the climatic changes. As long as these changes are incremental, it may be possible to adapt; however, unexpected, abrupt climatic jumps are possible and can lead to devastating consequences. The ability of human societies to adapt also depends on the economic resilience of the country affected; the developing nations will likely be most vulnerable. This adds an important ethical dimension to consideration of the climate change issue, because emissions of greenhouse gases are dominantly from the industrialized countries.


Climate Change 1995: The Science of Climate Change (IPCC, 1996).


Climate Change 1995: Impacts, Adaptations, and Mitigation (IPCC, 1996).

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