Physical manifestations and ecological implications of Arctic Atlantification

The Atlantic gateway to the Arctic Ocean is influenced by vigorous inflows of Atlantic Water. The high-latitude impacts of these inflows have strengthened owing to climate change, particularly since 2000, driving so-called ‘Atlantification’ — a transition of Arctic waters to a state more closely resembling that of the Atlantic. In this Review, we discuss the physical and ecological manifestations of Atlantification in a hotspot region of climate change spanning the southern Barents Sea to the Eurasian Basin. Atlantification is driven by anomalous Atlantic Water inflows and is modulated by local processes, including: reduced atmospheric cooling, which amplifies warming in the southern Barents Sea; reduced freshwater input and stronger influence of ice import in the northern Barents Sea; and enhanced upper ocean mixing and air–ice–ocean coupling in the Eurasian Basin. Ecosystem responses to Atlantification encompass increased production, northward expansion of boreal species (borealization), an increased importance of the pelagic compartment populated by new species, an increasingly connected food web and a gradual reduction of the ice-associated ecosystem compartment. Considering the complex evidence supporting Atlantification, dedicated, multidisciplinary observations and advanced modelling experiments targeting large-scale changes in the system and specific mechanisms responsible for local and remote changes are urgently needed. Since 2000, oceanographic conditions in the Barents Sea and the Eurasian Basin have transitioned from those reflecting the Arctic to a state more closely resembling that of the Atlantic. This Review examines the physical and ecological manifestations, drivers and implications of this so-called Atlantification.