The ICES Working Group on Oceanic Hydrography met via video conference between 11th and 21st April, 2022 to review the 2021 oceanographic conditions in the North Atlantic. The WGOH members are custodians of some of the longest sustained time series of ocean observations, with many now extending more than forty years. Their joint analysis has strengthened individual organisational efforts to provide the following Highlights for the North Atlantic 2021.
Highlights for the North Atlantic 2021
The record low salinities, first observed in the sub-polar gyre between 2016-2017, have continued to spread out (within expected timelines) along the main circulation pathways, both northwards (into the North Sea, Nordic Seas, Barents Sea, and Fram Strait) and southwards (into the sub-tropical gyre).
Low salinity anomalies are now also apparent deeper in the water column, therefore, making this no longer an exclusive surface feature.
Salinities in the sub-polar gyre itself, and the immediate downstream pathways (e.g., Atlantic Water in the Faroe Current, Faroe Bank Channel, and deep regions west of Scotland) have increased to near average.
Record low salinity in surface waters of the Bay of Biscay, the Iberian coast, the Gulf of Cadiz and the Canaries is changing water column stratification (i.e., increasing the buoyancy anomaly). For example, in the Bay of Biscay and Iberian coast, the salinity of the upper 500 m is the lowest observed in approximately the last 3 decades.
Temperatures across the surface North Atlantic and the inflowing Atlantic Water to the Norwegian Sea and Barents Sea remain close to the long-term average. However, the deep waters in the Nordic Seas and associated overflow branches have continued to warm. In some regions (e. g., the Greenland Sea between 700-2000 m) this warming appears to have slowed (or even stopped).
Record warming was observed on the continental shelves of the western North Atlantic in 2021. Near-bed ocean temperatures were substantially above normal across the region, including record highs in the northern Gulf of St. Lawrence, off southern Newfoundland and across the Northeast US Shelf.
Sea ice area in the Barents Sea was much lower in 2021 compared to previous years. A new seasonal low record of sea ice volume occurred in the Gulf of St Lawrence since records began in 1969.
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