Persistent Quaternary climate refugia are hospices for biodiversity in the Anthropocene

Climate stability leads to high levels of speciation and reduced extinction rates, shaping species richness patterns. Hotspots of species diversity often overlap with regions that experienced stable temperatures and, perhaps, variable rates of precipitation during the late Quaternary. These hotspots potentially harbour many species with low vagility and small geographical ranges, making them more vulnerable to future ecoclimatic change. By comparing global and regional patterns of cli- mate stability during short periods of unusually large and wide- spread climate changes since the Last Glacial Maximum with twenty-first-century patterns, we show that human-driven climate change will disproportionally affect biodiversity in late Quaternary climate refugia, ultimately affecting the species, communities and ecosystems that are most vulnerable to cli- mate change. Moreover, future changes in absolute temperature will probably erode the mechanisms that are theorized to sustain biodiversity hotspots across time. These impending shifts from stable to unstable temperatures—projected for the majority of the world’s biodiversity regions—threaten to reduce the size and extent of important climatic safe havens for diversity. Where climate refugia are forecast to persist until the end of this century, temperatures in these refuges are likely to exceed the acclimation capacity of many species, making them short-term hospices for biodiversity at best.