Combining future projections of land-use and climate change to assess their impact on biodiversity
Authors: Hari Chantal , Vanderkelen Inne , Fischer Markus , Davin Édouard 
Published: February 2023

Biodiversity loss, land degradation, and climate change are acknowledged environmental challenges faced by humanity. Human activities including land-use changes are key stressors for biodiversity, thus, future projections of biodiversity impacts need to include both climate change and land-use change. While a lot of studies focused on mapping and projecting the vulnerability of multiple species based on different climate mitigation scenarios or warming levels, land-use trajectories are often not included in these projections. Recent work made first steps to address these deficiencies. For example, Hof et al. (2018) evaluated potential future impacts of climate and land-use changes on global species richness of terrestrial vertebrates under a low and high emission scenario. However, they used the same land-use change assumptions for both emission scenarios. In this study, we aim to fill the described research gap by combining future climate scenarios and a matrix of land-use projections derived from integrated assessment modeling (IAM) to estimate the fractional land-use patterns, underlying land-use transitions, and key agricultural management information, to assess the impact of climate change on biodiversity and quantify the additional impact of land-use change.&#160;To this end, we use the global simulations with a species distribution model from the Hof et al. (2018) study forced by four GCMs and both RCP2.6 and RCP6.0 climate scenarios following the ISIMIP2b simulation protocol and apply a land-use filter on the species occurrence probabilities to determine the implications for the world&#8217;s amphibians, mammals and reptiles at a 0.5&#176; resolution. The land use data used to include future projections of land-use change is the Land Use Harmonization dataset v2 (LUH2). LUH2 reconstructs and projects changes in land use among 12 categories. To match the species&#8217; habitat preferences, data from IUCN Habitat and Classification Scheme for each species is mapped onto the 12 land-use types represented in the LUH2 dataset according to the conversion table from Carlson et al. (2022). The land-use data is then used to refine the climatic envelope and filter out regions where species cannot persist.&#160;This approach allows to quantify the change of the proportion of affected species distributions between different climate and land-use scenarios and combinations of both. In addition, it provides quantitative information on the impact of future climate change on biodiversity accounting for the combination of land-use change projections and climate-driven species distribution models.&#160;Key Reference: Hof, C., Voskamp, A., Biber, M. F., B&#246;hning-Gaese, K., Engelhardt, E. K., Niamir, A., Willis, S. G., & Hickler, T. 2018: Bioenergy cropland expansion may offset positive effects of climate change mitigation for global vertebrate diversity. Proceedings of the National Academy of Sciences of the United States of America, 115(52), 13294&#8211;13299.