A critical assumption underlying projections of biodiversity responses to global warming is that species distributions are at equilibrium with their environment. Nevertheless, most species occupy a broad thermal distribution, and overall community-level outcomes of local mismatches between species’ thermal limits and environmental temperatures have not yet been considered. Here we examine the geographic and thermal distributions of marine species worldwide, and identify large-scale spatial thermal mismatches, or biases, where communities are dominated by species with warmer or cooler affinity than local environmental temperatures. We combine information on the magnitude of this thermal bias with local warming rates to predict vulnerability of ecological communities to local warming-related loss of species. We find that proximity to thermal limits, as inferred from present-day species distributional ranges, far outweighs spatial variation in warming rates in contributing to the proportion of species predicted to be lost from ecological communities under projected ocean warming over the next century.
News story - Citizen scientists change understanding of how global warming affects marine biodiversity - 11 November 2015