This NCEAS working group proposes to synthesize existing data from 26 circumpolar arctic and alpine sites regarding species response to a common temperature manipulation. The sites are part of the International Tundra Experiment (ITEX), a collaboration of arctic and alpine researchers. ITEX programs have been in place throughout the circumpolar arctic and temperate alpine since 1992 or 1993. ITEX investigators use a common experimental design, work with a common set of species, and monitor common parameters of the ecosystem and physical environment. ITEX investigators seek to understand how the same species located in different geographical areas respond to warming and natural climatic variability, and how changes in those species and their environments will affect overall ecosystem structure and function. A common assumption in ecological studies is that patterns of response in species (or other groupings such as functional types or ecosystems) can be directly extrapolated to the range of the species or type. Such an assumption is necessary if data are to be used in modeling and extrapolation studies. The ITEX data will allow us to explicitly test this assumption by examining variability in tundra responses at multiple sites over 4-5 years. We have compiled and integrated data sets from ITEX research sites in order to test hypotheses of tundra response at a global scale using meta-analysis techniques.