Climate-driven connectivity loss impedes species adaptation to warming in the deep ocean

Marine life are expected to have fewer thermal barriers restricting their movement to adjacent habitats than terrestrial species do. However, it remains unknown how this warming-induced connectivity loss varies in different ocean strata, limiting the predictability of warming impacts on biodiversity in the whole ocean. Here, we developed a climate connectivity framework across seascape strata under different climate change scenarios, which combines thermal gradient, human impacts and species tolerance thresholds. We show that warming may lead to connectivity loss, with its magnitude increasing with depth. Connectivity loss is projected to increase rapidly in 2050, particularly in deep strata, and may impair the movement capacity of deep-sea phyla in adapting to warming. With the compression of habitat ranges, over one-quarter of deep-sea species inhabit areas that may experience disrupted connectivity, threatening the maintenance of deep-sea biodiversity. Our results highlight the challenges that climate change poses to biodiversity conservation through disruption of deep-sea connectivity. The authors demonstrate that warming will reduce connectivity for ocean species, potentially limiting their capacity to adapt to warming through habitat shifts. The results show particularly strong losses of connectivity in deeper ocean strata, affecting 95% of abyssopelagic species.