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.