Future climate and land use changes are expected to affect species globally both independently and by exacerbating one another’s effects. Estimating how these potential large-scale biodiversity perturbations are expected to vary with different socioeconomic scenarios is key for informing decision-making and policy and important input for ongoing IPBES (International Panel on Biodiversity and Ecosystem Services) global assessment.
A new generation of climate and land use change projections to 2070 now enable a fresh examination of how land-cover and climatic changes combine to form species-level threats and how these vary among scenarios, regions, and taxa. We estimated realized climate niche boundaries for ca. 20,000 terrestrial vertebrates (amphibians, mammals, birds) based on expert-based information on occurrence and land-cover association. We first evaluated how climate conditions would shift outside of species’ current known niche limits under projected future climate change and cause range contractions. We then examined how projected land cover changes separately result in the potential loss of habitat-suitable range within species current extent. Finally, we assessed how both factors combine in their effect on projected species distributions and how their respective and joint effects vary among taxa, regions.
Results/Conclusions
Our primary finding is that the loss of suitable areas due to land cover changes is the same order of magnitude as that of climatic shifts by 2050. Species globally are projected to see dramatic reductions in habitat-suitable range, include hundreds of cases where a lack of appropriate dispersal may result in species extinctions. Depending on scenario, on average, amphibians were projected to lose 43-54% of suitable habitat, while mammals and birds would lose 20-30% and 4-15%, respectively. Amphibians experience the greatest losses in South America, Southeast Asia and Mesoamerica, largely following patterns of species richness, however Ocean and the Caribbean are projected to have greater loss (on average 41% and 44% loss across species), in proportion to species richness. Patterns of mammal habitat loss were not highly correlated with species richness, with sub-Amazonian South America experiencing the greatest proportional losses (32%). Bird habitat loss largely followed patterns of richness, with disproportionately lower loss in Southeast Asia (12%).