This is 900,000km2 below the 1981-2010 average maximum extent \u2013 the historical baseline against which more recent sea ice extent is typically compared.\u00a0<\/p>\n
According to one expert, the \u201clengthening trend of lower Antarctic sea ice poses real concerns regarding stability and melting of the ice sheet\u201d.<\/p>\n
Meanwhile, at the Earth\u2019s other pole, Arctic sea ice reached its annual minimum<\/a> on 10 September, ranking as the joint-10th lowest in the satellite record.<\/p>\n At 1.6m km2, the 2025 minimum shares the spot with 2008 and 2010. The NSIDC notes that all 19 of the lowest sea ice extents in the record have occurred in the past 19 years.<\/p>\n Antarctic peak<\/p>\n For decades, scientists have been using satellite data to track the annual cycle of sea ice growth and melt at the world\u2019s poles. This is a key way to monitor the \u201chealth\u201d of sea ice in both the Arctic and Antarctic.<\/p>\n The map below shows Antarctic sea ice on the day of its maximum extent for the year on 17 September 2025, where the yellow line shows the 1981-2010 average.<\/p>\n The NSIDC<\/a> says that sea ice extent was \u201cmarkedly below average\u201d in the Indian Ocean and the Bellingshausen Sea, but \u201cslightly above average\u201d over the Ross Sea.<\/p>\n In an NSIDC press release announcing the Antarctic maximum, Dr Ted Scambos<\/a>, a senior research scientist at the Cooperative Institute for Research In Environmental Sciences<\/a>, said:<\/p>\n \u201cThe lengthening trend of lower Antarctic sea ice poses real concerns regarding stability and melting of the ice sheet. However, it may also be leading to greater snowfall over the continent, which would slow the progression of sea level rise.\u201d<\/p>\n<\/blockquote>\n Antarctic sea ice growth<\/p>\n In its typical annual cycle, Antarctic sea ice grows during winter towards its annual maximum extent in September or October. It then melts throughout the spring and summer towards its March minimum.<\/p>\n Earlier this year, Antarctic sea ice recorded its second-smallest summer minimum<\/a> on record.<\/p>\n At 1.98m m2, this was the fourth consecutive year that Antarctic sea ice had fallen below 2m km2, the NSIDC<\/a> noted.<\/p>\n In its monthly sea ice updates, the NSIDC reported that sea ice then grew at a \u201cnear-average pace\u201d. During this period, sea ice \u201cexpanded rapidly\u201d in the last areas to lose ice, including the Ross Sea and eastern Weddell Sea, it said.<\/p>\n The NSIDC explained that sea ice rebounded quickly in the Ross Sea area because ice extent had retreated \u201cslowly\u201d there the month before \u2013 meaning that the upper ocean layer did not have time to accumulate heat which would slow the winter freeze.<\/p>\n In April, \u201cthe situation in the Antarctic remained fickle\u201d, the NSIDC<\/a> said. At the beginning of the month, sea ice extent neared \u201crecord-low\u201d daily extents, but as the month progressed ice cover expanded \u201cfairly quickly\u201d, it said.<\/p>\n May had \u201cbelow average growth<\/a>\u201d in Antarctic sea ice and saw the fifth lowest record for Antarctic sea extent.<\/p>\n As June began, the the Bellingshausen Sea and eastern Queen Maud Lord regions were \u201cfar behind\u201d in ice re-growth, it said, adding that the Bellingshausen Sea was almost entirely ice-free as temperatures were 6-8C above average.<\/p>\n In June, Antarctic sea ice was 1.28m km2 below the 1981-2010 baseline, with \u201cparticularly low\u201d sea ice extent in the Bellingshausen Sea and the Indian Ocean sector, according to the NSIDC<\/a>. This was the third-lowest sea ice extent ever recorded for the month of June, it said.\u00a0<\/p>\n Throughout July, Antarctic sea ice extent grew at a \u201cslower-than-average\u201d rate, according to the NSIDC<\/a>. By the end of the month, Antarctic sea ice extent was 1.3m km2 below the baseline, it noted.<\/p>\n Arctic melt season<\/p>\n In the Arctic, sea ice cover typically reaches its high point in March, before dropping to its September minimum at the end of the northern-hemisphere summer.<\/p>\n The 2025 Arctic sea ice winter peak was the smallest<\/a> since satellite records began. The peak, recorded on 22 March, was 1.31m km2 below the average maximum for the 1981-2010 historical baseline.<\/p>\n In March, Arctic sea ice extent averaged 14.14m km2 \u2013 the lowest in the satellite record, according to the NSIDC<\/a>. It noted that, at the time,\u00a0 average air temperature was above the historical baseline across much of the Arctic region.\u00a0<\/p>\n Arctic sea ice extent then \u201cchanged very little\u201d throughout April, remaining \u201cnearly constant\u201d until the final days of the month, the NSIDC<\/a> reported.<\/p>\n It added that the final days of April saw Arctic sea ice extent drop due to ice retreat along the coast of the Barents Sea.<\/p>\n According to data, the main reason why the April total extent remained largely flat was due to an increase of sea ice in the northeastern Barents Seas that \u201coffset\u201d losses elsewhere.<\/p>\n Below-average air temperatures over the northern Norwegian and Barents Seas was the most \u201cnotable feature\u201d of April 2025, the NSIDC<\/a> said.<\/p>\n May was marked by a decline in Arctic sea ice extent at a faster-than-average pace, the NSIDC<\/a> noted,\u00a0 resulting in the seventh-lowest May extent on record.\u00a0<\/p>\n It added that ice loss in May was \u201cprimarily\u201d in the Barents Sea, Bering Sea and the Sea of Okhotsk.<\/p>\n In June, Arctic sea ice extent averaged 10.48m km2 \u2013 the second-lowest average on record for the month, the NSIDC<\/a> said. It noted that sea ice hit record-low levels over 20 June and 26 June and tracked at \u201cnear-record\u201d low levels through the month. The Barents and Kara Seas were both \u201cnearly ice-free\u201d by the end June.<\/p>\n Hudson Bay ice extent was also \u201cconsiderably below average\u201d throughout June and northern parts of Baffin Bay were nearly ice-free, it said.<\/p>\n By the end of July, daily sea ice extent in the Arctic had fallen to 7.66m km2 \u2013 the third lowest in the satellite record, the NSIDC<\/a> reported. It noted that, for most of the month, Arctic sea ice extent tracked close to levels recorded for 2012 \u2013 the year in which Arctic sea ice extent reached its lowest-ever September minimum.<\/p>\n Throughout August, the NSIDC<\/a> reported that sea ice \u201crapidly melted and compacted\u201d north of Alaska in the Beaufort Sea, with sea ice extent averaging at 5.41m km2 \u2013 the seventh lowest on record.\u00a0<\/p>\n Dr Zack Labe<\/a> \u2013 a climate scientist at Climate Central<\/a> \u2013 tells Carbon Brief that northern Siberia<\/a> saw August air temperatures more than 5C above the 1981-2010 average, resulting in \u201ca striking amount of open water along the Atlantic side of the Arctic that would normally be ice-covered\u201d.<\/p>\n At an annual minimum of 1.6m km2, this year\u2019s Arctic minimum is \u201cpretty unremarkable\u201d, Labe tells Carbon Brief, and \u201cadds to the evidence of a clear slowdown in the rate of summer Arctic sea ice loss\u201d.<\/p>\n However, Labe stresses that this is \u201cnot surprising\u201d \u2013 referencing a recent study which \u201cclearly shows how internal variability can temporarily drive periods of slower melt in a warming climate, as well as periods of rapid melt, such as in the early 2000s\u201d. (For more on this research<\/a>, read Carbon Brief\u2019s guest post).<\/p>\n He adds:<\/p>\n \u201cIt is only a matter of time before summertime melt accelerates again. This is not a good news story, especially since in many other months we still see a clear downward trend\u2026<\/p>\n<\/blockquote>\n \u201cWhile the past decade of summers may give the appearance of a slowdown, regional extremes such as in the Kara Sea this year underscore that the Arctic is already radically different from past decades. The driver is clear \u2013 human-caused climate change.\u201d<\/p>\n<\/blockquote>\n Satellite switch<\/p>\n For decades, NSIDC has tracked sea ice using data from weather satellites run by the US Navy. However, earlier this year, Mongabay<\/a> reported that NSIDC scientists \u201cnoticed holes in the data they were receiving\u201d.<\/p>\n The article explains:<\/p>\n \u201cWhen scientists inquired with the Department of Defense (DoD), they were told not all data were being downloaded and access to the data had been deprioritised. Soon after, the DoD said it would stop sharing\u2026data altogether, citing military cybersecurity risks in the old systems.\u201d<\/p>\n<\/blockquote>\n NSIDC scientist Walt Meier told Science<\/a> that while the US satellites \u201care up there and functioning\u2026we\u2019re not getting all the data anymore, at least regularly\u201d.<\/p>\n The DoD then set a cut-off date<\/a> to \u201ccease distribution data from the Defense Meteorological Satellite Programme\u201d on 31 July.<\/p>\n In June, the NSIDC announced<\/a> that it would \u201cexplore switching to a different sensor<\/a>\u201d aboard a Japanese satellite that was launched in 2012.<\/p>\n The only other option available to NSIDC was a \u201cseries of Chinese weather satellites, which the country is already using to produce its own record of sea ice\u201d, Science noted. It added that a new US DoD weather satellite, launched last year, is \u201calso capable of collecting similar data, but its data have not yet been made public\u201d.<\/p>\n![\"Antarctic](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/unnamed.png\")
Antarctic sea ice extent on 17 September. Median sea ice edge for 1981-2010 is shown in yellow. Source: NSIDC<\/a>. <\/p>\n\n
![\"Map](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/1759419428_925_image.png\")
Map showing the main regions of the Antarctic. Credit: Carbon Brief <\/p>\n![\"Antarctic](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/Screenshot-2025-10-01-at-10.52.50-AM.png\")
<\/p>\n![\"Map](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/1759419429_825_image-1.png\")
Map showing main regions of the Arctic. Credit: Carbon Brief <\/p>\n![\"Zack](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/Screenshot-2025-10-01-at-10.56.16-AM.png\")
<\/a><\/p>\n![\"Arctic](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/Screenshot-2025-10-01-at-10.58.10-AM.png\")
<\/p>\n![\"Zack](\"https:\/\/www.europesays.com\/ie\/wp-content\/uploads\/2025\/10\/Screenshot-2025-10-01-at-10.59.39-AM.png\")
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