Two poles, two paths: what September sea ice reveals

In September 2014, Antarctic sea ice covered more ocean than in any other September in the satellite record. Two years earlier, Arctic September ice had reached its lowest monthly average. The poles were telling very different stories.

By September 2026, the Arctic averaged 4.81 million square kilometres of sea ice; Antarctica averaged 17.32 million. Those are very different areas, and September means opposite seasons: late summer in the north, late winter in the south. The chart keeps the same scale for both.

The Arctic’s lower summers

In the first September of this record, 1979, the Arctic averaged 7.05 million square kilometres. By 2012 it had fallen to 3.57 million, the lowest September monthly average in the series. September 2026 was larger than 2012, but still 25% below the 1981–2010 September average.

Individual years move up and down. The long view makes the direction clearer: a partial recovery from an extreme year does not return the Arctic to the conditions common in the early satellite record.

Antarctica’s reversal

Antarctic September ice followed a less straightforward path. Its 2014 monthly average was 19.76 million square kilometres, the highest in this record. In 2023 it fell to 16.89 million, the lowest. September 2026 reached 17.32 million, still about 6% below its own 1981–2010 September average.

Antarctica has much more sea ice than the Arctic in September. Each line measures a different ocean, in a different season. The comparison shows how a long Arctic decline and a more variable Antarctic history can coexist—and why one exceptional year cannot explain either pole.

The ice floats over ocean and changes with wind and weather. Extent measures ocean areas where satellite cells contain at least 15% sea ice; it is not ice thickness or volume. These are September monthly averages, not the single-day annual minimum and maximum reported in the news.