26 March 2024, Carbon Brief: Antarctic sea ice ‘behaving strangely’ as Arctic reaches ‘below-average’ winter peak. Antarctic sea ice is “behaving strangely” and might have entered a “new regime”, the director of the US National Snow and Ice Data Centre (NSIDC) tells Carbon Brief. Following an all-time low maximum in September 2023, Antarctic sea ice has been tracking at near-record-low extent for the past six months. Last month, it hit its 2024 minimum extent, tying with 2022 for the second-lowest Antarctic minimum in the 46-year satellite record. Dr Mark Serreze, director of the NSIDC tells Carbon Brief that more warm ocean water is reaching the surface to melt ice and keep it from forming. He says that we “must wait and see” whether this is a “temporary effect” or whether the Antarctic has entered a “new regime”. Meanwhile, Arctic sea ice has reached its maximum extent for the year, peaking at 15.01m square kilometres (km2) on 14 March. The provisional data from the NSIDC shows that this year’s Arctic winter peak, despite favourable winds that encouraged sea ice formation, was 640,000km2 smaller than the 1981-2010 average maximum. This year’s maximum was the 14th lowest in the satellite record. “Overall, the road remains downhill for Arctic sea ice, but it is quite bumpy along the way,” another scientist tells Carbon Brief. This relatively high winter peak is “notable and a good reminder that we have to communicate and account for this type of weather variability when we talk about Arctic climate change”, he says. He adds that although the maximum is high compared to recent years, the ice is still “much thinner” than it was a few decades ago. The “wide coverage of this thinner ice” means total Arctic sea ice volume for the month of February was the third lowest on record. Record-breaking Antarctic extent Antarctic sea ice has been tracking at or near record-low levels for months. The Antarctic set a record-low maximum on 10 September 2023, with an extent of 16.96m km2. This was “the lowest sea ice maximum in the 1979 to 2023 sea ice record by a wide margin”, and one of the earliest, the NSIDC says. Antarctic conditions over 2023 were “truly exceptional” and “completely outside the bounds of normality”, one expert told Carbon Brief. As 2023 progressed, Antarctic sea ice melt was “slower than average”, the NSIDC says. The total decline in Antarctic sea ice extent through October was 903,000km2, while the October average was 985,000km2. Nevertheless, Antarctic sea ice extent continued to track at a record low. On 31 October 2023, Antarctic sea ice extent was still tracking at a record-low of 15.79m km2. This is 750,000km2 below the previous 31 October record low. The decline in Antarctic sea ice paused for a few days from 9 November, allowing sea ice extent to creep above the November 2016 value, the NSIDC says. This marked the first time that the daily 2023 Antarctic sea ice extent was not the lowest in the record since early May 2023. By the start of December, Antarctic sea ice extent was again at a record low, it notes. The Antarctic saw in the new year with a sea ice extent of 6.37m km2, marking the sixth-lowest New Year’s Day Antarctic sea ice extent on record, the NSIDC says. Ice melted rapidly throughout the month, and by the end of January, daily Antarctic sea ice extent reached 2.58m km2 – tying with 2017 for second lowest on record. Read more here