Borealization: a biodiversity refugium and evolutionary cradle during the Permian-Triassic climate crisis

Understanding how organisms track suitable environments during rapid climate change is constrained by the brevity of modern observations. Using the fossil record, we identify the mid- to high-latitude Boreal Ocean as a regional biodiversity refugium during the Permian-Triassic climate crisis. Additional Boreal successions indicate sustained diversity and comparatively hospitable conditions. Biogeographic reconstructions reveal that 30% of Sassendalen taxa survived the extinction event, with two-thirds expanding or shifting their latitudinal ranges into the Boreal Ocean. More than 90% of newly evolved species originated there, and their lineages subsequently dispersed at differing rates into other regions throughout the Early Triassic. These findings identify poleward migration and high-latitude refugia as key drivers of biodiversity persistence and evolutionary recovery during climate crises.