REVIEW SUMMARY◥CLIMATE CHANGEThe broad footprint of climate changefrom genes to biomes to peopleBrett R. Scheffers,*Luc De Meester, Tom C. L. Bridge, Ary A. Hoffmann,John M. Pandolfi, Richard T. Corlett, Stuart H. M. Butchart, Paul Pearce-Kelly,Kit M. Kovacs, David Dudgeon, Michela Pacifici, Carlo Rondinini, Wendy B. Foden,Tara G. Martin, Camilo Mora, David Bickford, James E. M. WatsonBACKGROUND:Climate change impacts havenow been documented across every ecosystemon Earth, despite an average warming of only~1°C so far. Here, we describe the full rangeand scale of climate change effects on globalbiodiversity that have been observed in nat-ural systems. To do this, we identify a set ofcore ecological processes (32 in terrestrial and31 each in marine and freshwater ecosystems)that underpin ecosystem functioning and sup-port services to people. Of the 94 processesconsidered, 82% show evidence of impact fromclimate change in the peer-reviewed literature.Examples of observed impacts from meta-analyses and case studies go beyond well-established shifts in species ranges and changesto phenology and population dynamics to in-clude disruptions that scale from the gene tothe ecosystem.ADVANCES:Species are undergoing evolu-tionary adaptation to temperature extremes,and climate change has substantial impactson species physiology that include changes intolerances to high temperatures, shifts in sexratios in species with temperature-dependentsex determination, and increased metaboliccosts of living in a warmer world. These phys-iological adjustments have observable impactson morphology, with many species in bothaquatic and terrestrial systems shrinking inbody size because large surface-to-volume ratiosare generally favored under warmer conditions.Other morphological changes include reduc-tions in melanism to improve thermoregula-tion, and altered wing and bill length in birds.Broader-scale responsesto climate change includechanges in the phenology,abundance, and distribu-tion of species. Temperateplants are budding andflowering earlier in springand later in autumn. Comparable adjustmentshave been observed in marine and freshwaterfish spawning events and in the timing of sea-sonal migrations of animals worldwide. Changesin the abundance and age structure of popula-tions have also been observed, with widespreadevidence of range expansion in warm-adaptedspecies and range contraction in cold-adaptedspecies. As a by-product of species redistributions,novel community interactions have emerged.Tropical and boreal species are increasinglyincorporated into temperate and polar commu-nities, respectively, and when possible, lowlandspecies are increasingly assimilating into moun-tain communities. Multiplicative impacts fromgene to community levels scale up to produceecological regime shifts, in which one ecosys-tem state shifts to an alternative state.