This paper summarizes information on California's Holocene environments and presents archaeological evidence for some dramatic cultural adjustments from natural changes. Some goals include showing how archaeology may be used: (1) to help validate models of environmental change developed in other sciences; (2) to independently discover environmental trends and conditions; (3) to add the dimension of human adaptation to studies of environmental change; and (4) to show how natural changes affected particular localities. Findings not only suggest how archaeology may contribute to better paleoenvironmental reconstructions, but also raise questions about the long-term viability of current land use patterns in the far west.