Modelling the temporal dynamics of climate suitability for marine biodiversity

Andreas L. S. Meyer, African Climate and Development Initiative, University of Cape Town, Cape Town, South Africa, Alex L. Pigot, Genetics, Evolution and Environment, UCL, London, United Kingdom, Cory Merow, Department of Ecology and Evolutionary Biology, University of Connecticut, Storss, CT and Christopher Trisos, African Climate and Development Initiative, University of Cape Town, Cape Town, MD, South Africa

Background/Question/Methods
As climate warming intensifies, an increasing number of species are becoming exposed to conditions beyond their niche limits. As a result, many species are shifting their geographic ranges to track suitable conditions over space and time. These range shifts occur through the colonization of newly suitable habitats and extirpation of populations. However, the expected timing of these events under future warming, and the resulting temporal dynamics of ecological assemblages, are not well known. This is in part because many biodiversity forecasts to date have focused on single snapshots of the future. To address this, we introduce the concept of the ‘climate suitability’ profile, which describes changes in the cumulative number of species projected to lose or gain suitable conditions at a site over time. We illustrate this framework using yearly sea surface temperature forecasts from multiple climate models to generate climate suitability profiles for shallow water marine assemblages globally.

Results/Conclusions
By comparing the rate at which suitable climate conditions for resident species are lost to the rate at which a cell becomes suitable for non-resident species, our approach reveals the projected temporal dynamics of biodiversity change that could occur under future climate warming. Moreover, the suitability profiles may provide a hint on whether climate-related declines or increases in species richness are likely to be transient or permanent. By examining the shapes of climate suitability profiles and how these vary across taxa, regions (e.g. tropical vs temperate), and future emission scenarios, we show how this new approach can provide novel insights into the risk of early or abrupt changes in species richness and composition over the coming decades.