Safeguarding global terrestrial vertebrate species from future sea level rise

Abstract Climate-driven sea-level rise (SLR) poses growing threats to terrestrial ecosystems. Despite its far-reaching ramifications for global biodiversity, our understanding of when, where, and which species will be most affected by SLR remains limited. Here, we provide a global assessment of terrestrial vertebrate species’ exposure to SLR and potential refugia by integrating high-precision relative SLR projections, man-made flood-defense barriers, and Areas of Habitat (AOH) maps for 33,818 terrestrial vertebrate species. Considering five Shared Socioeconomic Pathways (SSPs), we found that SLR will affect up to 13,416 (including 2,075 threatened) species by 2050 and 15,009 (2,593 threatened) species by 2100, representing 57–63% of birds, 47–52% of mammals, 26–35% of reptiles, and 20–24% of amphibians. The average proportion of habitat inundated for reptile species is nearly twice that of birds or mammals. Species with narrow AOHs – particularly reptiles and birds with small breeding grounds – face elevated extinction risk due to SLR. Regardless of SSPs, inland areas predicted to be inundated in Southeast Asia are consistently those that currently support exceptionally high species richness, rarity-weighted richness, and threatened species richness. Although the implementation of flood-defenses barriers may mitigate SLR impacts in populated areas, key biodiversity hotspots (e.g., Southeast Asia, Amazon River delta) remain highly exposed, especially after 2050. This highlights the need to protect SLR refugia, many of which are in low- and middle-income countries. Overall, SLR is expected to affect a broad spectrum of species, with effects intensifying after 2050. Early international actions, including climate mitigation, targeted conservation of range-restricted species, adoption of eco-friendly barriers, and protection of key refugia, are urgently needed to prevent irreversible biodiversity loss.