Background/Question/Methods
Climate change is one of the major threats to biodiversity, inducing shifts in species distributions and species richness patterns. The current distribution of global plant species richness can be reasonably well explained by climate and environmental factors. According to the water-energy-richness hypothesis, energy is the most important determinant of species richness at high latitudes, whereas water availability is more important in the rest of the world where energy is not the limiting factor. Based on this hypothesis, we build a multipredictor model for global contemporary species richness across 1,032 geographic regions worldwide. The resulting relationship is applied on two contrasting global greenhouse gas emission scenarios used by the Intergovernmental Panel of Climate Change (IPCC), in combination with corresponding future climate surfaces from 5 global climate models (GCMs) per 110x110km equal area grid. The pessimistic A1FI scenario implies a likely global surface temperature rise of 4.0°C, whereas the moderate B1 scenario indicates an average warming of 1.8°C. Our approach allows the spatially explicit quantification of the magnitude and direction of the possible impact of the predicted climate change on the overall distribution of global plant diversity.
Results/Conclusions
In global average, the capacity for species richness per standard area decreases by 10.4% in the A1FI scenario, whereas it remains similar to today in the B1 scenario (+0.2%). Both models indicate is a strong deviance in the predicted changes amongst different geographic regions. More than 50% of all species occurring in many tropical and subtropical drylands and in south-western Amazonia are predicted to be exposed to unsuitable climate by 2100, whereas the capacity for species richness may increase by more than 10% in Arctic and many temperate regions. However, any rapid shift in contemporary climate conditions causing changes in the capacity for species richness according to our global models may have negative impacts on contemporary floras caused by species turnover and local extinction. The respective consequences for native floras and ecosystem functionality should be considered in climate-change integrated conservation strategies and management plans.
