Future seasonal changes in habitat for Arctic whales during predicted ocean warming

Ocean warming is causing shifts in the distributions of marine species, but the location of suitable habitats in the future is unknown, especially in remote regions such as the Arctic. Using satellite tracking data from a 28-year long period, covering all three endemic Arctic cetaceans (227 individuals) in the Atlantic sector of the Arctic, together with climate models under two emission scenarios, species distributions were projected to assess responses of these whales to climate change by the end of the century. While contrasting responses were observed across species and seasons, long-term predictions suggest northward shifts (243 km in summer vs. 121 km in winter) in distribution to cope with climate change. Current summer habitats will decline (mean loss: -25%), while some expansion into new winter areas (mean gain: +3%) is likely. However, comparing gains vs. losses raises serious concerns about the ability of these polar species to deal with the disappearance of traditional colder habitats.

Methods
To test if Arctic cetaceans will respond differently to ocean warming in areas west and east of Greenland, we utilized a large tracking dataset spanning 28 years, including sub-populations from all three Arctic endemic cetaceans in the Atlantic sector of the Arctic (n=227 individuals; bowhead whale, beluga and narwhal). Using environmental data from three different Global Climate Models (GCMs) from the Coupled Model Intercomparison Phase 6 (CMIP6), a series of species distribution models were used to (i) predict current and (ii) project future (up to 2100) distributions of the three whale species in our study region, and to (iii) assess habitat and latitudinal changes in response to global warming.