Changes in Arctic and Antarctic sea-ice properties and processes

Abstract

Although sea ice covers only ~9% of the world’s oceans, its presence and absence greatly alter the energetic balance of Earth’s climate. Owing to geographic differences, Arctic and Antarctic sea ice have different dominant properties and processes, which in turn produce different responses to natural climate variability and anthropogenic climate change. This Review surveys the changes in sea-ice properties and processes of the Arctic and Antarctic environments. The Arctic melt season has lengthened by ~7.4 days per decade during 1979–2024, alongside decreases in winter sea-ice thickness (1.6 m mean total over 1980–2023), summer surface albedo (0.03 per decade over 1979–2020) and spring snow depth (2.5 cm per decade over 1954–2024). Changes in the Antarctic are smaller than those in the Arctic owing to contrasting regional and temporal trends. From a dynamic perspective, sea-ice motion in both hemispheres has increased, by 0.63 cm s–1 per decade in the Arctic (1978–2024) and 0.69 cm s–1 per decade in the Antarctic (1982–2024), whereas trends in polynya occurrence differ by region. This Review highlights major knowledge gaps and provides recommendations for joint model-observation efforts to improve understanding of sea ice and its role in Earth’s climate system. Sea ice modulates the energy exchange between the atmosphere and ocean through complex, time-varying processes. This Review describes changes in Arctic and Antarctic sea-ice properties and processes, discusses the future sea-ice environment and provides recommendations to improve understanding of sea ice and its role in Earth’s changing climate.