The goal of the U.S. Global Change Research Program (USGCRP) is to gain an understanding of complex Earth Systems so that change can be predicted and a scientific basis for formulating national and international policy can be established. The USGCRP has three objectives: documenting the Earth’s system through careful coordinated observations; improving scientific understanding of the processes; and developing models that will allow accurate global and regional predictions. Improvements in computer technology, including the use of coupled models, are making it possible to document how the different components of the Earth system work together. With increased understanding of these interactions, capabilities for predicting global change and associated natural hazards will be greatly increased.