The geologic record preserves the integrated response of the Earth system to many perturbations. The study of Earth system history provides unique information on natural variability, the coupling of the components of the Earth system, the biosphere response to global change, and the global and regional response to abrupt changes. Earth system history also has the potential to supply case studies of past global change which are essential to assess the response of climate models to altered boundary conditions. For these reasons, Earth system history has become a key element of the U.S. Global Change Research Program (USGCRP).