This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Data from many sources, including NASA, have shown a significant decrease in Arctic sea ice since 1979. However, the processes driving the melting and freezing of sea ice are complex, and fluctuations occur throughout the year.
Short-term variations in temperature, winds, ocean convection and water salinity within a certain region can also affect how much ice can reform or melt. A recent study, published in Polar Science, indicates that a region of the Greenland Sea near the West Jan Mayen Ridge has experienced an increase in winter sea ice over the past couple of years, resulting in a recurrence of a feature called the Odden ice tongue. The recurrence suggests a confluence of interesting processes that may lead to a better understanding of short-term variability in sea ice.
Near Jan Mayen, a Norwegian volcanic island in the Arctic Ocean, sea ice once often formed a long, curved feature called the Odden ice tongue. Historical research found that Odden was especially prominent in the 1980s and 1990s. The feature became far less common after the early 2000s as the regional ice edge retreated and failed to reform regularly.
Previous satellite records showed strong year-to-year swings in the feature's extent, and other studies linked its size to variations in cold air, winds, ocean temperature, salinity and ice transported by currents. The authors involved in the new study say that periods of large sea-ice extent often coincide with Great Salinity Anomalies (GSAs). Freshwater from continental river outflow and sea ice melt flows through the Greenland Sea and into the Atlantic.
Because freshwater mixing into salty seawater results in salinity changes that facilitate freezing, large freshwater outflow from the Arctic Ocean can lead to these GSAs farther downstream. The study authors write, "While Odden did form locally in some years, it is also reported to consist of advected sea ice in other years." The team used remote sensing data from 2017 through 2024 to analyze sea ice extent around Jan Mayen for each month over the years. Radar observations were checked against an independent satellite record of ice concentration, as well as sea-surface and air-temperature data.
The data showed a surprising expansion of sea ice near Jan Mayen in 2023 and early 2024 after several relatively low-ice years. The study's largest measurement was in January 2024, at about 20,300 square kilometers, covering 39.5% of the study area. This was the largest expansion in many years, although the researchers say the Odden formation still did not develop to its full extent as seen at its peak.
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