Incorporating future climate uncertainty into the identification of climate change refugia for threatened species

Climate change presents a substantial threat to species unable to keep pace via migration or adaptation. In-situ climate refugia, areas currently occupied by a species and that remain suitable in the future, will be vital for species with dispersal limitations. Ex-situ refugia, areas beyond species' current ranges that remain suitable, may facilitate range shifts or provide options for translocation. Assessing both refugia is a conservation priority. Here, we identify refugia for 319 species threatened in New South Wales, using four plausible scenarios describing futures that are Warmer/Wetter, Warmer/Drier, Hotter/Wetter and Hotter/Little Precipitation change, relative to the present. Using Maxent, we identify (a) in-situ refugia for each species under each scenario; (b) regions of consensus – areas projected as in-situ refugia across all scenarios; (c) hotspots of in-situ refugia (regions suitable for >1 species); and (d) regions of consensus for ex-situ refugia. Species were categorised based on the extent of in- and ex-situ refugia. By 2070, refugia will likely be broadest, and narrowest, under the Warmer/Wetter and Hotter/Wetter scenarios, respectively. East coast regions currently suitable for multiple species are unlikely to remain as hotspots. Most species (65%) are projected to have limited regions of consensus for either refugia. Translocation should be explored for species with little-to-no in-situ refugia, but for which ex-situ refugia exist. Management of existing populations will be critical for species with in-situ refugia but limited ex-situ. We highlight how management decisions based on agreement across climate scenarios can be made, irrespective of uncertainty about the magnitude of climate change.