Potential Consequences of Regional Species Loss for Global Species Richness: A Quantitative Approach for Estimating Global Extinction Probabilities

Because the biosphere is highly heterogeneous, species diversity impacts are typically assessed at local or regional scales. Because regional species richness impact metrics refer to different species compositions, they cannot be easily compared or aggregated to global impacts. Translating regional species richness impacts into global impacts allows for comparisons between impacts and facilitates the estimation of global species extinctions. This requires a conversion (or weighting) factor that takes into account the characteristics of regionally specific species compositions. We developed a methodology for deriving such conversion factors based on species' habitat ranges, International Union for Conservation of Nature threat levels, and species richness. We call these conversion factors global extinction probabilities (GEPs) of the reference location or region. The proposed methodology allows for the calculation of GEPs for any spatial unit and species group for which data on spatial distribution are available and can be implemented in methodologies like life cycle impact assessment. Furthermore, the GEPs can be used for the identification of conservation hot spots. The results of the proposed GEPs (for various taxonomic groups) show that the risk that regional species loss may result in global species extinctions significantly differs per region and informs where irreversible biodiversity impacts are more likely to occur.