Antarctic sea ice ‘behaving strangely’ as Arctic reaches ‘below-average’ winter peak

Antarctic sea ice ‘behaving strangely’ as Arctic reaches ‘below-average’ winter peak

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Antarctic sea ice is “behaving unusually” and may need entered a “new regime”, the director of the US National Snow and Ice Data Centre (NSIDC) tells Carbon Temporary.

Following an all-time low most in September 2023, Antarctic sea ice has been monitoring at near-record-low extent for the previous six months. Final month, it hit its 2024 minimal extent, tying with 2022 for the second-lowest Antarctic minimal within the 46-year satellite tv for pc report.

Dr Mark Serreze, director of the NSIDC tells Carbon Temporary that extra heat ocean water is reaching the floor to soften ice and maintain it from forming. He says that we “should wait and see” whether or not this can be a “non permanent impact” or whether or not the Antarctic has entered a “new regime”.

In the meantime, Arctic sea ice has reached its most extent for the yr, peaking at 15.01m sq. kilometres (km2) on 14 March. The provisional data from the NSIDC exhibits that this yr’s Arctic winter peak, regardless of beneficial winds that inspired sea ice formation, was 640,000km2 smaller than the 1981-2010 common most.

This yr’s most was the 14th lowest within the satellite tv for pc report.

“General, the highway stays downhill for Arctic sea ice, however it’s fairly bumpy alongside the best way,” one other scientist tells Carbon Temporary. This comparatively excessive winter peak is “notable and a great reminder that we’ve to speak and account for one of these climate variability after we discuss Arctic local weather change”, he says.

He provides that though the utmost is excessive in comparison with current years, the ice continues to be “a lot thinner” than it was just a few many years in the past. The “huge protection of this thinner ice” means whole Arctic sea ice quantity for the month of February was the third lowest on record.

Arctic winter peak

Arctic sea ice extent modifications all year long. It grows every winter earlier than reaching its peak for the yr in February or March after which melts all through the spring and summer time in direction of its annual minimal, usually round September. 

Utilizing satellite tv for pc knowledge, scientists can observe the expansion and soften of sea ice, permitting them to find out the scale of the ice sheet’s winter most and summer time minimal extent. These are key metrics to observe the “well being” of the Arctic sea ice.

The NSIDC’s announcement says that this yr’s Arctic winter peak of 15.01m is “beneath common”. Clocking in at 640,000km2 beneath the 1981-to-2010 common most extent, it ranks because the 14th lowest within the satellite tv for pc report.

The NSIDC provides that the date of the utmost this yr, 14 March, was two days later than the 1981-to-2010 common date of 12 March.

The plot beneath exhibits Arctic sea ice extent on 14 March, with the typical sea ice extent for 1981-2010 proven by the orange line.

Arctic sea ice extent on 14 March 2024. Median sea ice edge for 1981-2010 is shown in orange.
Arctic sea ice extent on 14 March 2024. Median sea ice edge for 1981-2010 is proven in orange. Supply: NSIDC.

Arctic freeze

“The highway stays downhill for Arctic sea ice, however it’s fairly bumpy alongside the best way,” Dr Zack Labe – a postdoctoral researcher working at NOAA Geophysical Fluid Dynamics Laboratory and the atmospheric and oceanic sciences programme at Princeton University – tells Carbon Temporary. He provides:

“Whereas this winter was but once more in keeping with the long-term pattern towards a hotter Arctic with much less ice, regional climate patterns can nonetheless contribute to ice growth and slower internet declines, particularly if the winds align from a north-to-south path.”

Arctic sea ice reached its minimum extent for 2023 on 19 September.

With an extent of 4.23m km2, this was the sixth-lowest minimal on report and 1.99m km2 beneath the typical minimal recorded over 1981-2010. 

Following its annual minimal, Arctic sea ice development was “slower than common”, resulting in the fifth-lowest September on report, in keeping with the NSIDC

Labe tells Carbon Temporary that the freeze season began with “widespread open water throughout the Pacific facet of the Arctic, with huge areas of ice missing north of Alaska”, which contributed to “well-above-average temperatures” within the area. 

All through October, nevertheless, sea ice extent elevated by 119,800km2 per day – quicker than the 1981-2010 common of 89,200km2 per day, in keeping with the NSIDC

The Arctic freeze up was “notably fast” within the seas round Siberia. By the top of October, the ice cowl had reached the Siberian coast, though open water remained within the Beaufort and Chukchi Seas.

Air temperatures over the Arctic Ocean, round 2,500 ft above floor degree, have been principally above common throughout October – notably in and across the Canadian Archipelago, which noticed temperatures of 4-5C above common.

Zack Labe on X: Canadian Arctic Archipelago and Beaufort Sea

Labe tells Carbon Temporary that, general, the Arctic winter could be characterised by “uncommon heat within the northern Arctic, however better whole ice extent”. This “counterintuitive” dynamic was attributable to atmospheric circulation patterns, which led to “hotter, moist air blowing towards the north pole, whereas northerly winds contribute to increasing ice within the Greenland Sea and Sea of Okhotsk”, he says.

All through November, Arctic sea ice extent continued to extend quicker than common. Nevertheless, the NSIDC says the freeze up “briefly stalled” for round 5 days from 22 November, as a collection of three tropical cyclones introduced heat, moist air into the north Atlantic.

The NSIDC says {that a} mixture of low strain to the north and west of Svalbard and a high-pressure centre to the south-east “created a powerful, persistent circulate from the south of comparatively heat and moist air from the north Atlantic Ocean towards Svalbard”.

This circulate of air could be seen as “an extension of an atmospheric river into the Arctic”, it says. It provides that the sturdy winds “helped to push the ice edge within the east Greenland and Barents seas northwards, limiting new ice formation”. 

The NSIDC notes that pauses in Arctic sea ice freeze up have occurred in November earlier than, in 2013 and 2016, making such occasions “uncommon, however not unknown”.

Arctic sea ice extent continued to extend “markedly quicker” than traditional all through December, the NSIDC says. It provides that “sea ice formation in Hudson Bay was unusually late, however the ice cowl expanded rapidly from west to east in mid-December”.

For December general, 2023 noticed the third-highest month-to-month achieve on report, with 2.71m km2 of sea ice extent added all through the month. Common Arctic sea ice extent over December 2023 was the ninth lowest within the satellite tv for pc report, at 12m km2. 

Arctic sea ice extent continued to maneuver down the rankings as the brand new yr rolled in, regardless of slower-than-average ice development. In actual fact, the NSIDC says that Arctic sea ice extent really declined for just a few days on the finish of the month, though it notes that that is “commonplace at the moment of yr” and says it’s “attributable to climate methods that briefly halt ice development or push the ice northwards”.

The typical Arctic sea ice extent for January 2024 was 13.92m km2 – the 20th lowest on record.

This comparatively excessive sea ice extent is “notable and a great reminder that we’ve to speak and account for one of these climate variability after we discuss Arctic local weather change”, Labe tells Carbon Temporary. 

Arctic sea ice extent continued to develop all through February, gaining 15.3m km2 of ice all through the month. The February 2024 extent of 14.61m km2 was 690,000km2 beneath the 1981-2010 February common extent, and tied with 2022 because the fifteenth lowest on report, in keeping with the NSIDC.

Temperatures are often “well-below freezing” over the Arctic Ocean in February, however the NSIDC notes that in 2024, they weren’t as little as traditional for the time of yr. Over the central Arctic ocean, air temperatures at 2,500 ft above sea degree have been as much as 10C hotter than common. 

Labe notes that though sea ice extent was excessive in comparison with current years, the ice continues to be “a lot thinner” than it was just a few many years in the past: 

“Whole Arctic sea-ice quantity ended up because the third lowest on record for the month of February as a result of huge protection of this thinner ice.”

Antarctic ‘behaving unusually’

In the meantime, on the Earth’s different pole, Antarctic sea ice hit its summer time minimal sea ice extent on 20 February. With an extent of 1.99m km2, this yr’s minimal ties with 2022 because the second-lowest on report, the NSIDC reviews. 

The plot beneath exhibits Antarctic sea ice extent on 20 February 2024, with the median sea ice extent for 1981-2010 proven by the orange line.

Antarctic sea ice extent on 20 February 2024. Median sea ice edge for 1981-2010 is shown in orange.
Antarctic sea ice extent on 20 February 2024. Median sea ice edge for 1981-2010 is proven in orange. Supply: NSIDC.

The Antarctic minimal was 850,000km2 smaller than the 1981-to-2010 common summer time low of two.84m km2, however 200,000km2 bigger than the earlier report low set on 21 February 2023. 

This yr marks the third consecutive minimal Antarctic sea ice extent beneath 2m km2. The desk beneath exhibits the 5 years with the bottom minimal Antarctic sea ice extent on report, which incorporates 2022, 2023 and 2024 in direction of the highest. 

Rank Yr Minimal ice extent (m km2) Date
1 2023 1.79 21 Feb
2 2022 1.98 25 Feb
2= 2024 1.99 20 Feb
4 2017 2.11 3 March
5 2018 2.22 21 Feb

The Antarctic has been behaving unusually,” Dr Mark Serreze, director of the NSIDC, tells Carbon Temporary. He continues:

“Up to now few years, [southern hemisphere] summer time extent has dropped to report lows. Earlier than that, we noticed report highs! What has modified?

“The reply appears to lie within the ocean – extra heat water getting up the the floor to soften ice or maintain it from forming. Is that this a brief impact, or, as many have argued, have we entered a ‘new regime’ by which the ocean will proceed to strongly have an effect on the ocean ice? Once more, we should wait and see.”

Report-breaking Antarctic extent

Antarctic sea ice has been monitoring at or close to record-low ranges for months.

The Antarctic set a record-low most on 10 September 2023, with an extent of 16.96m km2. This was “the bottom sea ice most within the 1979 to 2023 sea ice report by a large margin”, and one of many earliest, the NSIDC says.

Antarctic circumstances over 2023 have been “actually distinctive” and “utterly exterior the bounds of normality”, one knowledgeable instructed Carbon Brief.

As 2023 progressed, Antarctic sea ice soften was “slower than common”, the NSIDC says. The full decline in Antarctic sea ice extent via October was 903,000km2, whereas the October common was 985,000km2.

Nonetheless, Antarctic sea ice extent continued to trace at a report low. On 31 October 2023, Antarctic sea ice extent was nonetheless monitoring at a record-low of 15.79m km2. That is 750,000km2 beneath the earlier 31 October report low.

The decline in Antarctic sea ice paused for just a few days from 9 November, permitting sea ice extent to creep above the November 2016 worth, the NSIDC says. This marked the primary time that the day by day 2023 Antarctic sea ice extent was not the bottom within the report since early Could 2023. By the beginning of December, Antarctic sea ice extent was once more at a report low, it notes

The Antarctic noticed within the new yr with a sea ice extent of 6.37m km2, marking the sixth-lowest New Yr’s Day Antarctic sea ice extent on report, the NSIDC says. Ice melted quickly all through the month, and by the top of January, day by day Antarctic sea ice extent reached 2.58m km2 – tying with 2017 for second lowest on report.

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