The future impacts of climate change are predicted to significantly affect the survival of many species. Recent studies indicate that even species that are relatively mobile and/or have large geographic ranges may be at risk of range contractions or extinction. An ecologically and evolutionary significant group of mammals that has been largely overlooked in this research is Australia's large marsupial herbivores, the macropodids (kangaroos). The aims of our investigation were to define and compare the climatic conditions that influence the current distributions of four sympatric large macropodids in northern Australia (Macropus antilopinus, Macropus robustus, Macropus giganteus, and Macropus rufus) and to predict the potential future impact of climate change on these species. Our results suggest that contemporary distributions of these large macropodids are associated with well-defined climatic gradients (tropical and temperate conditions) and that climatic seasonality is also important. Bioclimatic modeling predicted an average reduction in northern Australian macropodid distributions of 48% +/- 16.4% in response to increases of 2.0 degrees C. At this temperature, the distribution of M. antilopinus was reduced by 89% +/-0.4%. We predict that increases of 6.0 degrees C may cause severe range reductions for all four macropodids (96% +/-2.1%) in northern Australia, and this range reduction may result in the extinction of M. antilopinus.