evidence: Antarctic sea ice is a critical component of the global climate system1,2,3. Climatologically, Antarctic sea ice reaches its annual minimum in mid-February to early March. Sea ice coverage in January and February 2023 broke monthly and daily sea ice extent records for this time of year4. On 10 February 2023, sea ice coverage broke the record daily minimum of 1.91 million square kilometres set one year earlier on 21 February 20224,5. On 19 February 2023, a new minimum Antarctic sea ice extent of 1.77 million square kilometres was observed4, 1.02 million square kilometres (36%) less than the 1979-2022 average daily minimum sea ice coverage. [...] The multi-decade increase in Antarctic sea ice that peaked in 2014, identified here as a high sea ice state between mid-2007 and mid-2016, has been examined extensively, with contributions from high-latitude winds12,13 and Antarctic meltwater14,15 suggested to have played a role. Positive ocean-sea ice feedbacks may have perpetuated the high sea ice coverage16 during this period. In spring 2016, Antarctic sea ice rapidly transitioned to a new, low sea ice state.