Antarctic Sea Ice

Antarctic sea ice rings the continent and swings through a strong seasonal cycle, from roughly 3 million square kilometers in February to about 18 million in September. Unlike the steadily shrinking Arctic, Antarctic extent drifted slightly upward into the 2010s before a sharp, record-low drop from 2023 that researchers are still attributing between ocean heat, winds, and natural variability. Most of it is first-year ice that melts out each summer, so multi-year ice is comparatively scarce.