Humans are causing significant global environmental changes, including warmer temperatures, increased atmospheric nitrogen (N) deposition, and more frequent and intense El Nino events. Although each of these factors can have major impacts on plant community composition and ecosystem processes, it is not known how these factors will interact to affect ecosystem dynamics in the future. Furthermore, although arid and semiarid systems cover approximately a third of the earth’s surface, few experimental warming studies have been conducted in these systems. We are conducting a multi-factorial global change field experiment in an arid grassland community at the Sevilleta.