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 way in which,” Dr Zack Labe – a postdoctoral researcher working at NOAA Geophysical Fluid Dynamics Laboratory and the atmospheric and oceanic sciences programme at Princeton College – tells Carbon Temporary. He provides:
“Whereas this winter was but once more in step with the long-term development towards a hotter Arctic with much less ice, regional climate patterns can nonetheless contribute to ice enlargement and slower web declines, particularly if the winds align from a north-to-south path.”
Arctic sea ice reached its minimal extent for 2023 on 19 September.
With an extent of 4.23m km2, this was the sixth-lowest minimal on file and 1.99m km2 under 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 file, in line with the NSIDC.
Labe tells Carbon Temporary that the freeze season began with “widespread open water throughout the Pacific aspect of the Arctic, with huge areas of ice lacking north of Alaska”, which contributed to “well-above-average temperatures” within the area.
All through October, nonetheless, sea ice extent elevated by 119,800km2 per day – sooner than the 1981-2010 common of 89,200km2 per day, in line with the NSIDC.
The Arctic freeze up was “notably fast” within the seas round Siberia. By the tip 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 toes above floor stage, have been largely above common throughout October – notably in and across the Canadian Archipelago, which noticed temperatures of 4-5C above common.
Labe tells Carbon Temporary that, general, the Arctic winter will be characterised by “uncommon heat within the northern Arctic, however higher complete 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 sooner 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 stress to the north and west of Svalbard and a high-pressure centre to the south-east “created a robust, persistent circulate from the south of comparatively heat and moist air from the north Atlantic Ocean towards Svalbard”.
This circulate of air will 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 sooner” 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 shortly from west to east in mid-December”.
For December general, 2023 noticed the third-highest month-to-month acquire on file, 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 file, 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 reality, the NSIDC says that Arctic sea ice extent really declined for a number of days on the finish of the month, though it notes that that is “commonplace right now of yr” and says it’s “attributable to climate programs that briefly halt ice development or push the ice northwards”.
The common Arctic sea ice extent for January 2024 was 13.92m km2 – the twentieth lowest on file.
This comparatively excessive sea ice extent is “notable and a very good reminder that we’ve got to speak and account for this sort of climate variability once we speak about 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 under the 1981-2010 February common extent, and tied with 2022 because the fifteenth lowest on file, in line 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 toes above sea stage 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 remains to be “a lot thinner” than it was a number of a long time in the past:
“Whole Arctic sea-ice quantity ended up because the third lowest on file 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 file, the NSIDC reviews.
The plot under 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 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 file low set on 21 February 2023.
This yr marks the third consecutive minimal Antarctic sea ice extent under 2m km2. The desk under exhibits the 5 years with the bottom minimal Antarctic sea ice extent on file, which incorporates 2022, 2023 and 2024 in the direction of the highest.
Graph: Carbon Temporary
“The Antarctic has been behaving unusually,” Dr Mark Serreze, director of the NSIDC, tells Carbon Temporary. He continues:
“Prior to now few years, [southern hemisphere] summer time extent has dropped to file lows. Earlier than that, we noticed file highs! What has modified?
“The reply appears to lie within the ocean – extra heat water getting as much as the floor to soften ice or hold it from forming. Is that this a short lived impact, or, as many have argued, have we entered a ‘new regime’ through which the ocean will proceed to strongly have an effect on the ocean ice? Once more, we should wait and see.”
Document-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 file by a large margin”, and one of many earliest, the NSIDC says.
Antarctic circumstances over 2023 have been “really distinctive” and “utterly exterior the bounds of normality”, one professional advised Carbon Temporary.
As 2023 progressed, Antarctic sea ice soften was “slower than common”, the NSIDC says. The whole decline in Antarctic sea ice extent by way of October was 903,000km2, whereas the October common was 985,000km2.
However, Antarctic sea ice extent continued to trace at a file low. On 31 October 2023, Antarctic sea ice extent was nonetheless monitoring at a record-low of 15.79m km2. That is 750,000km2 under the earlier 31 October file low.
The decline in Antarctic sea ice paused for a number of 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 every day 2023 Antarctic sea ice extent was not the bottom within the file since early Could 2023. By the beginning of December, Antarctic sea ice extent was once more at a file 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 file, the NSIDC says. Ice melted quickly all through the month, and by the tip of January, every day Antarctic sea ice extent reached 2.58m km2 – tying with 2017 for second lowest on file.
This story was printed with permission from Carbon Temporary.
