NOAA Arctic Report Card 2025 : Atlantification of the Arctic Atlantification of the Arctic Ocean

Oceanic currents play an important role in the Arctic region by bringing oceanic heat to the Arctic Ocean from the lower latitude regions (Fig. 1). In the early 1890s, Nansen and his crew aboard the Fram made the first measurements in the Eurasian Basin, observing that warm, salty water from the Atlantic Ocean flows northward into the Arctic Ocean at 150-800 meters depth. They also observed near-freezing and relatively fresh water in the upper ~50 m and a layer with large vertical salinity and density gradients (called the Arctic halocline) overlying the Atlantic Water (AW) at ~50-150 m depth.