State Transitions of Arctic Sea Ice During 1979–2024 and Its Mechanisms

Amplified Arctic warming has led to a pervasive decline in sea ice cover over recent decades, yet the pattern and governing mechanisms of sea-ice concentration (SIC) state transitions remain unclear. This study reveals a stepwise reduction in ice extent during 1979-1991, 1992-2006, and 2007-2024, with pronounced regional SIC contrasts in these transitions. September-mean sea ice in the 70°N-80°N Arctic belt undergoes sustained and significant retreat across three periods, while localized ice gains emerge north of Greenland. In February, the Greenland and Barents Seas exhibit persistent ice loss, whereas the central Arctic Ocean shows significant ice increases. Enhanced ice-albedo feedback, together with concurrent rises in 2-m air temperature and sea surface temperature, dominates ice loss across the 70°N-80°N Arctic belt and the Greenland and Barents Seas. Meanwhile, wind-driven ice convergence promotes localized ice gains north of Greenland in September and within the central Arctic Ocean in February, with both mechanisms amplified during 2007-2024. These findings underscore the spatial heterogeneity of Arctic SIC transitions and highlight the complex interplay of thermodynamic and dynamic processes shaping them.