Mapping refugia -- places where current biodiversity can persist, adapt and, in due course, disperse from -- identifies opportunities for conservation management to attenuate the pace and severity of ecosystem simplification and biodiversity loss [1, 2]. We model the current and future distribution of Holdridge Life Zones [3] (HLZs) to identify areas where current bioclimatic conditions are expected to persist [4]. Even under the most severe 21st century climate scenario (SSP5-8.5), current bioclimatic conditions persist across many areas that are ecologically intact [5] as measured by the Human Footprint Index [6] (HFI). The extent of refugia ranges from 1% in the tundra biome to 33% in the tropics and 34% of polar regions. Refugia are underrepresented in protected areas. We introduce a Biodiversity Density Index (BDI), analogous to the Biodiversity Intactness Index [7, 8] (BII), to rank refugia by their mammal biodiversity and propose BDI as an index to monitor the effectiveness in retaining biodiversity over time. Our results can help prioritize mutually supportive strategies to attenuate the sixth mass extinction event . These include enhanced protection of large refugia from human impacts, climate-adaptive management of small refugia, and monitoring the pace of biodiversity changes at multiple scales.