Lowest Arctic sea-ice extent

The lowest ever Arctic sea-ice extent was recorded on 17 September 2012, with only 3.39 million square kilometres (1.3 million square miles) of ice remaining at the end of the Arctic summer. Each winter, the Arctic Ocean freezes over and forms sea-ice that is just a few tens of centimetres thick and which shrinks the following summer. Scientists have been measuring the summer sea-ice extent since the late 1970s and have reported dramatic declines. Overall, the downward trend in minimum sea-ice extent is 13% per decade, relative to the 1981–2020 average. This equates to a loss of around 80,000 square kilometres (30,900 square miles) of sea ice per year, which is roughly the size of Austria.

Most experts predict the first "ice-free" Arctic Ocean will occur before 2050 and possibly as early as 2040.

At the opposite pole, the lowest Antarctic sea-ice extent occurred on 25 February 2022, when it was measured at 1.92 million km2 (741,300 sq mi).