The fundamental physics of an enhanced greenhouse effect due to fossil fuel combustion is well understood, and Earth is warming (IPCC 2007). Considerable uncertainty exists regarding the impacts of climate change, but high latitudes and high elevations are thought to be leading indicators of future trends. The suite of high-elevation lands protected by the National Park Service is ideal in terms of documenting and monitoring the physical, floral, and faunal impacts of climate change. Indeed, the network of alpine lands managed by the Park Service in the mountainous western United States spans maritime-to-arid ecosystems over a dozen degrees of latitude (fig. 1). The web grows even farther if we consider alpine park units in Hawaii, Alaska, and the eastern United States. It is a network that has no other analog and offers unparalleled opportunities for global change monitoring.