Beyond the concept of oceanic islands as climatic refugia: A high resolution climate dataset for the Canary Islands, CanaryClim

Abstract

Understanding how grain size affects our ability to characterize species responses to ongoing climate change is of crucial importance in the context of an increasing awareness for the substantial difference that exists between macroclimates and the actual microclimate experienced by a given species. Climate change impacts on biodiversity are expected to peak in mountain areas and montane oceanic islands, wherein the differences between macro and microclimates are precisely the largest. Here, we generated fine-scale climatic data for the Canary Islands, a mountainous oceanic archipelago and a hotspot of endemism, and compared predictions of climate change impacts on species distributions using the newly generated data at 100 m resolution versus available data at 1 km resolution. In particular, we compared the accuracy and spatial predictions of ensemble of small models for 14 Macaronesian endemic bryophyte species using these two climate models: CHELSA (~1 km) and the newly generated CanaryClim (100 m). We also generated future climate data from five individual model intercomparison projects for three warming shared socio-economic pathways. Based on species distribution models generated from CanaryClim and CHELSA, we found that models exhibited a similar accuracy, but CanaryClim-based models predicted buffered warming trends in mid-elevation ridges. Although both climate datasets predicted similar, high future range loss, these were lower for a number of species with CanaryClim. Predicted mean range gains were substantially higher with CanaryClim than with CHELSA. Overall, predicted species extinctions were higher with CHELSA than with CanaryClim. Our results highlight the important role that fine resolution climate datasets can play in predicting the potential distribution of both microrefugia and new suitable range under warming climate across topographically complex oceanic archipelagos