Abstract
Earth is heading toward a sixth mass extinction event [1]. While the current extinction crisis (see Glossary) is driven mainly by land-use change, overharvesting, and biological invasions, climate change is becoming a major contributor to extinction and is exacerbating existing drivers [2,3]. Extinctions can cause cascading effects that alter ecosystem structure and functioning [1,4].
Climate change impacts are increasing in severity, and reversal is becoming unlikely, driving a paradigm shift in landscape conservation toward promoting climate-change resistance in low-vulnerability areas and facilitating inevitable transitions in more vulnerable areas [5,6]. In this context, climate-change refugia are seen as climate-resistant bastions [7-9] that remain relatively buffered from the effects of climate change. They constitute areas that biodiversity can retreat to and persist in [10,11], thereby facilitating persistence during periods of climate change [12,13]. As such, climate-change refugia are potential 'safe havens' for maintaining biodiversity under anthropogenic climate change and for abating the unfolding extinction crisis [8,14,15]. However, refugia must be integrated with other management considerations [7,10] and may have limits to how much climate change they can buffer [8,9,12,16,17]. Thus, it is important to understand the factors and processes that affect refugia function and quality and to prioritize areas for conservation that are likely to persist for longer time periods [15,17,18].
Here we first develop a conceptual model of the biological and physical factors that affect climate-change refugia. We then build on the concept of refugial capacity to illustrate how it can assist in identifying the most buffered and most persistent (i.e., long-term) safe havens for biodiversity. We highlight how managing climate-change refugia as complex and dynamic systems that are affected by global change is key to conserving them. Finally, we integrate these considerations into a conceptual framework of refugia-focused management that extends to the restoration of urban and degraded habitats.
Climate-change refugia can support biodiversity by maintaining buffered conditions despite climate change and are a critical tool for the unfolding extinction crisis.