The future-focused Proactive Conservation Index highlights unrecognized global priorities for vertebrate conservation

Human-induced environmental pressures are expected to intensify worldwide during the 21st century. Consequently, future-focused tools and approaches to anticipate pressures on biodiversity are key to effectively prioritize conservation actions and supplement existing approaches. Here, we develop a continuous conservation prioritization index, the Proactive Conservation Index (PCI), that integrates projected future extrinsic threats and traits that can predispose species' vulnerability. We used the PCI to assess the conservation priority of 33,560 species of land vertebrates worldwide, compared our results to the extinction risk categories of these species in the International Union for Conservation of Nature (IUCN) Red List of Threatened Species, and examined spatial and phylogenetic patterns in these species future conservation needs. We found that median PCI scores broadly followed the order expected under the IUCN Red List classification, but varied substantially within each IUCN Red List category. According to the PCI, reptiles will be the group of land vertebrates with highest conservation priority in the future, despite amphibians currently having the highest proportion of threatened species according to the IUCN Red List. The PCI revealed that species in the Near Threatened category will have future conservation needs more similar to species in threatened categories than to species in the Least Concern category. Arid ecoregions, tropical montane forests, and islands showed the highest differences between conservation priorities set using the PCI and the IUCN Red List, indicating possible unrecognized future conservation needs. The proportion of threatened species according to the IUCN Red List was uncorrelated with the protected area coverage of each ecoregion, while the PCI, by design, highlighted currently unprotected ecoregions with sensitive fauna that will have high exposure to threats in the future. We produced a user-friendly web application to display our results and an R package to enable users to calculate PCI scores for any taxon and region, customizing the index according to the severity of predicted threats and importance of species attributes in other systems. Our novel index can help practitioners prioritize fine-scale species conservation actions in light of future threats and different global change scenarios.