Antarctic sea ice reached its seasonal winter maximum on Sept. 17, 2025, but even at its greatest extent of the year, coverage remained strikingly low by historical standards. Satellite imagery and data highlighted by the NASA Earth Observatory show the difference between the 2025 extent and the long-term average, revealing substantial reductions around much of the Antarctic coastline.

What is it?

Antarctic sea ice plays a critical role in Earth’s climate and ecosystems, and understanding its variability is essential for interpreting broader environmental changes. Unlike the Arctic, which is an ocean surrounded by land, Antarctica is a continent surrounded by open ocean.

This geographic contrast allows Antarctic sea ice to expand freely during winter and retreat dramatically in summer,

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