With ongoing public concern regarding climate change and recent drought that has affected many areas of the western United States, this study provides context and direct evidence for the negative impact of water stress on forest ecosystems. The response of trees to drought is a tangible example of the impacts of climate change on terrestrial ecosystems and is understandable by the public and a broad scientific audience. Any sustained change in the growth rates of trees also affects carbon sequestration, biodiversity maintenance, and ecosystem resilience, influencing both productivity and susceptibility to other disturbances.