Global biodiversity decline has led to concerns over the status and maintenance of biodiversity, and has generated broad interest in investigating data and indicators that quantify the impact of threats and identify the greatest conservation concerns. While the causes of this biodiversity decline represent an area of active and ongoing research, climate and land-use change impacts on habitat are widely considered major drivers, and are likely to increase for this century. Here, we used 2050 climate and land-use forecasts, based on a business-as-usual climate and socio-economic scenario, to evaluate their combined future impacts on global distributions of 5,302 amphibians, 8,783 birds and 4,620 mammal species. Transparent, species-specific phenomenological models were used to determine how anticipated changes in projected climate and land-use patterns alter current distributions of species, allowing us to quantify extinction risk associated with range contractions. We accounted for habitat quality uncertainty by evaluating two scenarios that included or excluded future habitat in areas with secondary vegetation.
Our results indicated moderate habitat declines and elevated extinction risk for many species, with as many as 982 to 1124 species potentially being added to threaten Global International Union for Conservation of Nature (IUCN) Red List categories by 2050. We also show that the greatest proportion of species adversely affected by anticipated climate and land-use change impacts will occur in parts of Africa and the Americas. These finding demonstrate the usefulness of this approach as a first-cut biodiversity assessment for highlighting species and regions of conservation concern.