A broad set of climate-related variables were considered for inclusion in a quantitative model that partitions geographic space into bioclimate regions. Statistical screening produced a subset of relevant bioclimate variables, which were further compacted into fewer independent dimensions using principal components analysis (PCA). An ISODATA clustering routine was then used to classify the principal components into relatively homogeneous environmental strata. The Global Environmental Stratification (GEnS) consists of 125 strata, which have been aggregated into 18 global environmental zones, with a 30 arcsec resolution (equivalent to 0.86 km² at the equator). The GEnS provides a global stratification that can: a) quantitatively relate the spatial distribution of ecosystems to an identified set of bioclimatic parameters, b) provide a consistent methodology across landscapes and countries that have so far mostly been studied using different protocols, approaches and taxonomies, and c) allow for a statistical modelling of bioclimatic zonal shifts that can be used to estimate the direction and magnitude of impacts on ecosystems due to climatic changes.