"World leaders continue to debate the economic and social implications of global environmental changes, both natural and human-induced. The 1988 midwestern U.S. drought underscored the potential effects of a warm, dry summer, just as the climate of recent decades in the Sahel starkly reveals the human tragedy that can occur in marginal-subsistence zones of a changing planet. Furthermore, the linking of the antarctic ozone 'hole' to man-made chlorofluorocarbons (CFC 's) and the current debate over humanity's role in the 'greenhouse effect' have placed the environment high on the national and international agenda. The substantial costs associated with addressing global environmental changes require policy decisions be based on adequate scientific and economic knowledge. In virtually all these issues, the salient feature is the significant scientific uncertainty associated with predicting the behavior of the coupled ocean-atmosphere-land Earth system. To reduce this uncertainty, the U.S. Global Change Research Program (USGCRP) has been developed as a central component of the U.S. Government ' s approach to global environmental change and its contribution to worldwide efforts."
U.S. Global Change Research Program Resource Library: http://www.library.globalchange.gov/