This regional assessment examines the impacts of temperature change from 1951-2006 on natural resources in Arizona, New Mexico, Colorado, and Utah. It documents that warming has already affected habitats, watersheds, and species in the Southwest, by influencing the timing of seasonal events or amplifying the impacts of natural disturbances such as wildfire and drought. The report concludes that to begin adapting to climate change, natural resource managers should reevaluate the effectiveness of current restoration tools, modify resource objectives, learn from climate-smart adaptive management and monitoring, and share information across boundaries.