Sea-ice-loss slowdown modulates the sea surface salinification in the Kara–Laptev Seas since the 2008 summer

Abstract

Recent studies have revealed the slowed Arctic sea-ice loss, but its climate effect on the ocean system remains unclear. By examining reanalysis datasets, we illustrate a paradoxical regime shift characterized by sustained ice loss and surface salinification in the Kara–Laptev Seas (KLS) during boreal summer since 2008. A notable phase transition from surface freshening during one period (1997–2008) with rapid sea-ice melting to salinification during another period (2009–2020) with gentle sea-ice melting has been identified in the KLS. Using a mixed-layer salinity budget, we characterized quantitatively the role of ice melting in driving salinification across different seas. We show that the salinification observed post-2008 mainly arises from the weakened summer sea-ice-ocean freshwater input, particularly the localized reduction in ice volume during June–August. This recent salinification in the KLS likely maintains a relatively stable state in the thinner seasonal sea-ice prevailing in the new Arctic.

Keywords

• the slowed arctic sea-ice loss
• regime shift since 2008
• surface salinification
• weakened sea-ice-ocean freshwater input
• mixed-layer salinity budget
• Kara–Laptev Seas