Global temperatures have risen this century, with further warming expected over the next 50–100 years. Non-migratory species, unable to rapidly respond to climate change, are expected to shift their ranges poleward. A study of 35 non-migratory European butterfly species found that 63% have shifted their ranges northward by 35–240 km over the past century, while only 3% have shifted southward. The analysis, which excluded data influenced by non-climatic factors, provides the first large-scale evidence of poleward range shifts in entire species. These shifts reflect changes in extinction and colonization rates at range boundaries, rather than changes in individual movement patterns. The findings support the prediction that global warming will cause species to shift their ranges poleward.Global temperatures have risen this century, with further warming expected over the next 50–100 years. Non-migratory species, unable to rapidly respond to climate change, are expected to shift their ranges poleward. A study of 35 non-migratory European butterfly species found that 63% have shifted their ranges northward by 35–240 km over the past century, while only 3% have shifted southward. The analysis, which excluded data influenced by non-climatic factors, provides the first large-scale evidence of poleward range shifts in entire species. These shifts reflect changes in extinction and colonization rates at range boundaries, rather than changes in individual movement patterns. The findings support the prediction that global warming will cause species to shift their ranges poleward.