Late Miocene greening of the Peruvian Desert

The response of the hyperarid Pacific coast of South America to greenhouse warming remains highly uncertain but has profound implications for the future habitability of the region. Here, we present the first paleobotanical study documenting the Peruvian Desert’s response to the Late Miocene greenhouse climate, when radiative forcing was comparable to 21st century projections. Fossil leaves, wood, and pollen from the Pisco Formation lagerstätte indicate a diverse dry forest biome where an absolute desert is observed today. Rainfall at 8–6 Ma is estimated to have been three times higher than today, possibly due to a warmer Eastern Tropical Pacific Ocean or to more frequent El Niño events. Our results suggest that the impacts of tropical climate dynamical changes on ecosystems of the Pacific South American coast under greenhouse warming conditions may outweigh those of heat and evaporation, potentially enabling vegetation expansion, biome transformations, and enhanced habitability in this region.