The realised velocity of climate change reveals remarkable idiosyncrasy of species’ distributional shifts

Abstract

To date, our understanding of how species have shifted in response to recent climate warming has been based on a few studies with a limited number of species. Here we present a comprehensive, global overview of species distributional responses to changing climate across a broad variety of taxa (animals, plants, and fungi). We characterise species responses using a metric that describes the realised velocity of climate change: how closely species responses have tracked changing climate through time. In contrast to existing climate velocity metrics that have focused on space, we focus on species and index their responses to a null expectation of change in order to examine drivers of inter-specific variation. Here we show that species are tracking climate on average, but not sufficiently to keep up with the pace of climate change. Further, species responses are highly idiosyncratic, and thus highlight that projections assuming uniform responses may be misleading. This is in stark contrast to species present-day and historical climate niches, which show strong evidence of the imprint of evolutionary history and functional traits. Our analyses are a first step in exploring the vast wealth of empirical data on species historic responses to recent climate change.