Reducing uncertainty in projections of extinction risk from climate change

TLDR

Climate change threatens biodiversity, and species–climate envelope models are used to forecast extinction risk, but recent studies show high variability and a lack of data limits model testing. This study tests the predictive accuracy of species–climate envelope models by comparing projected and observed range shifts of 116 breeding bird species in Britain across two historical periods. Using range shift data from 1967–72 and 1987–91, the authors projected shifts with 16 alternative models (four methods, two data parameterizations, two presence–absence rules) for each species. Projected shifts varied widely, but consensus-based projections significantly improved agreement with observed shifts, providing empirical evidence that species–climate envelope models can accurately predict range changes when uncertainty is reduced.

Abstract

ABSTRACT Aim Concern over the implications of climate change for biodiversity has led to the use of species–climate ‘envelope’ models to forecast risks of species extinctions under climate change scenarios. Recent studies have demonstrated significant variability in model projections and there remains a need to test the accuracy of models and to reduce uncertainties. Testing of models has been limited by a lack of data against which projections of future ranges can be tested. Here we provide a first test of the predictive accuracy of such models using observed species’ range shifts and climate change in two periods of the recent past. Location Britain. Methods Observed range shifts for 116 breeding bird species in Britain between 1967 and 1972 ( t 1 ) and 1987–91 ( t 2 ) are used. We project range shifts between t 1 and t 2 for each species based on observed climate using 16 alternative models (4 methods × 2 data parameterizations × 2 rules to transform probabilities of occurrence into presence and absence records). Results Modelling results were extremely variable, with projected range shifts varying both in magnitude and in direction from observed changes and from each other. However, using approaches that explore the central tendency (consensus) of model projections, we were able to improve agreement between projected and observed shifts significantly. Conclusions Our results provide the first empirical evidence of the value of species–climate ‘envelope’ models under climate change and demonstrate reduction in uncertainty and improvement in accuracy through selection of the most consensual projections.