Deep-time geographic dynamics of climate shape global vascular plant diversity

Climate has been proposed to shape global biodiversity through multiple, competing mechanisms that emphasise either magnitude, spatial distribution, or temporal stability of climatic variables, without integrating these dimensions into a unified spatio-temporal framework. Here we quantify spatio-temporal climate change in both climatic and geographic spaces by tracing when and where climatic conditions have emerged, persisted, and shifted across the Earth’s surface over the past 50 million years. We compile the most comprehensive global vascular plant diversity map to date (350,864 species) to test how deep-time geographic dynamics of climate have influenced plant diversity patterns. We find that species-rich and evolutionarily diverse plant communities are associated with climates that originated early, remained geographically extensive over long time, and experienced moderate geographic shifts. These climates are primarily warm and humid, now dominant in the tropics but previously extending into high latitudes. Models incorporating climate and its deep-time geographic dynamics explain up to 95% of the global variation in plant diversity, with geographic extent and mobility of climate contributing over half the explanatory power for species richness, turnover, and phylogenetic diversity. This work addresses a fundamental question that has long been debated regarding the spatio-temporal impacts of ongoing climate change on biodiversity.