Long-term records of ocean conditions are rare for the surface and even more uncommon in the deep sea. The North Atlantic region is unique, having a relatively large number of locations where oceanographic data have been collected repeatedly for multiple years or decades. The longest records extend back more than a century, providing a vital, long-term perspective on the changing climate of one of the world’s most studied ocean basins.
At the heart of this effort is ICES Working Group on Oceanic Hydrography (WGOH), custodian of some of the longest-running time series of ocean observations. Every year, WGOH meets to examine the latest measurements of temperature, salinity, and oceanographic trends across the North Atlantic. Their collective findings are published in ICES Report on Ocean Climate, a key reference for the scientific community.
Highlights for the North Atlantic Ocean 2024
WGOH held their annual meeting from 25–28 March 2025, with some members gathering at the National Marine Fisheries Research Institute in Gdynia, Poland and more joining online to review the
2024 oceanographic conditions in the North Atlantic. Their joint analysis
has strengthened individual organizational efforts to provide the following highlights for the North Atlantic.
High sea surface temperatures
Sea surface temperatures (SST) were high across many regions of the North Atlantic in 2024. It was the warmest year
for the southeastern North Sea and German Bight since 1997. Record-high SST and record-low sea ice
were observed in the Gulf of St. Lawrence, and extreme surface marine heatwaves (ongoing periods of unusually
high warming) occurred during late summer in the Barents and Norwegian seas. Active summer upwelling in the
west Iberia/Gulf of Cádiz/Sahara-Canaries system kept coastal temperature close to normal or lower values.
Contrasting salinity trends in the North Atlantic
In 2024, the eastern and western basins of the North Atlantic showed contrasting salinity changes. Salinity levels
across the eastern Atlantic margin—from the eastern subpolar North Atlantic (SPNA) to the southern Barents
Sea, Northwest European Shelf (NWES), Bay of Biscay, and northwest Iberia—have been increasing from their
minima around 2020. Sustained high run-off from the continent has not significantly counteracted this trend in
those regions close to the coast. However, this rebound remains absent south of the southwestern Iberian Peninsula.
The upper layers of the western Atlantic margins exhibited freshening in 2024, particularly in the Gulf of St.
Lawrence’s deep channels and along the Scotian and Northeast US shelves, including the second-freshest year
on record in the Gulf of Maine. This signal stems from enhanced Labrador Current transport south of the Grand
Banks, displacing the saltier Gulf Stream waters. These circulation changes also coincided with important
freshwater anomalies in Baffin Bay, the Labrador Sea and on the Newfoundland and Labrador shelf system, but
the causal relationship between the salinity and circulation changes is not clear.
ICES Working Group on Oceanic Hydrography (WGOH) closely monitors the ocean conditions in ICES area by updating and reviewing results from standard hydrographic sections and stations. The group publishes summary information on climatic conditions in the North Atlantic in ICES Report on Ocean Climate (IROC).
