Since reliable and continuous satellite records began in 1979, there have been strong regionally- and seasonally-varying patterns of change and variability in sea-ice extent around Antarctica (Fig. 1) – in contrast to a largely uniform loss of sea ice across the Arctic. Notably, the region west of the Antarctic Peninsula to the eastern Ross Sea has experienced significant sea ice loss in concert with a strengthening of the Amundsen Sea Low and increased warm northerly winds. On the western Peninsula, the sea ice loss and associated regional warming has led to dramatic and complex ecosystem change (see Antarctic Sea Ice #2) and has also been implicated in major ice-shelf disintegration events on the Peninsula (see Antarctic Sea Ice #1). Elsewhere, sea-ice coverage has expanded but with substantial interannual variability. The sum of these differing regional and seasonal contributions is a slight increasing trend in overall sea-ice coverage of 1.0 ± 0.5% per decade (or about 11,300 km² per year) for 1979–2018 (Fig. 1a).