Ice–ocean albedo feedback as a key mechanism driving recent Antarctic summer sea-ice decline

Abstract Antarctic summer sea-ice extent has exhibited a remarkable declining trend since 2016, reaching a record minimum in February 2023. This decline could accelerate regional warming, disrupt deep water formation and carbon cycling, and negatively affect Southern Ocean ecosystems. However, the mechanism driving this decline remains incompletely understood. Our analyses of satellite sea-ice data and heat flux calculations suggest that the ice–ocean albedo feedback is one of the key contributing processes to the recent decline. During the early ice-melt season, wind-forced divergent ice motion increases the fraction of low-albedo open water. This enhances anomalous solar heating of the upper ocean, accelerating sea-ice melt and further expanding the open water fraction, creating a positive feedback loop. Additionally, we propose a simplified coupled model that captures the key aspects of the feedback process. This model qualitatively reproduces some of the observed variability, such as the recent declining trend, and the year of the record minimum. These findings demonstrate that wind-forced ice motion during the early melt season (early to mid-November) plays a key role in initiating this feedback mechanism, which should be considered in future sea-ice predictions.