- In October 2024, the mean sea-ice extent in the Arctic Ocean was ca. 6.11 million square kilometres – the fourth-lowest mean value since the beginning of satellite observations.
- A collection of comparatively old sea ice north of the Laptev Sea could be the result of changes in the ice drift; the drift pattern has been fairly unusual in the past three years.
- During the past month, the summertime melting of the sea ice continued. At the end of the month, the amount of remaining ice was only slightly above the value from the record low year 2023.
In October, winter began in the Arctic Ocean – with air temperatures below the freezing point, leading to the formation of new sea ice, especially in the Laptev Sea, the East Siberian Sea, and on the western margin of the Canadian Arctic Archipelago. Satellite data on the sea-ice concentration from 31 October 2024 indicates the presence of ice-free waters near the coast of the Kara Sea (Figure 1).
On the last day of October 2024, the sea-ice extent in the Arctic Ocean was roughly 7.93 million square kilometres. The mean value for the month was 6.11 million square kilometres, indicating a continuation of the long-term trend in declining Arctic sea-ice extent; compared to previous years, this year’s mean value for October is slightly below the trend line (Figure 2). Nevertheless, there was no new record low; the mean sea-ice extent in October has been lower several times in the past. If we compare the sea-ice extent on the last day of October, it has been lower in two previous years – in 2016 and 2020 (Figure 3).
When new ice begins to form depends on the water and air temperatures, although strong winds and low surface-water salinity can also accelerate the process. On the basis of the available data, it’s impossible to say which specific factors were responsible for the sluggish new-ice formation this autumn. However, it should be noted that in the still-ice-free areas of the Barents Sea, Beaufort Sea and Canadian Arctic Archipelago, the surface water was 2 to 4 degrees Celsius warmer than in the reference period 1971 to 2000 in October (Figure 4). At the same time, the air temperatures, measured at a pressure altitude of 925 hPA (ca. 760 metres), were on average 3 to nearly 6 degrees Celsius above the long-term mean for the period 1971 to 2000 in the aforementioned areas (Figure 5).
If we compare the mean sea-ice-covered area in October 2023 with the current monthly mean, it can be clearly seen that, except in the northern East Siberian Sea and around Wrangel Island, there was less sea ice in the marginal regions of the Central Arctic than at this time last year (Figure 6).
Due to the persistent sea ice near Wrangel Island and newly formed sea ice in the East Siberian Sea, Russia’s Northern Sea Route Administration was forced to close the waterway through the East Siberian Sea and Chukchi Sea for tankers and cargo ships without an ice class on 15 October 2024; in turn, it was closed to ships with low ice classes from 20 October – several weeks earlier than in previous years. According to the news portal High North News coverage from mid-October, it remains to be seen whether or not the authorities will actually enforce the restrictions. At the time of printing, there are e.g. still three Chinese heavy transports loaded with power-plant modules for a Russian LNG terminal making their long way to the Russian Arctic – one of which has no ice class, while the two others have a low one.
Unusual observation: Particularly old and thick ice north of the Laptev Sea
The sea-ice age in the Arctic remains at a very low level and the amount of particularly old ice (3 to 4 years or older), which typically accumulates off the northern coast of Canada, continues to decline. However, this year we observed a zone containing multiyear ice north of the Laptev Sea (Figure 7). Normally, the region is home to ice of between and one and two years in age, which forms along the Russian shelf margin during the winter and then drifts toward the North Pole.
Initial analyses of this unusual collection of ice have revealed that, although it was first formed in the Russian shelf seas, for years it could not be exported to the Central Arctic. Instead, the Central Arctic was largely supplied with ice by the Beaufort Gyre – at least in the past two years. This changed drift pattern is due to atmospheric factors: macro-scale air currents determine the main wind direction, and with it, the nature of the ice drift.
The sea-ice situation in the Antarctic
In the Antarctic, the summertime melting of the sea ice continued in October. From 1 to 31 October, the sea-ice extent shrank from 17.21 million to 15.69 million square kilometres – a decline of 1.52 million square kilometres, or an area more than 3.5 times the size of Germany. On the last day of October, the remaining extent was only slightly larger than on the same date last year (Figure 8). This trend should come as no surprise, given the extremely low maximum winter sea-ice extent this year.
If we compare the mean sea-ice extent in October 2024 with the long-term mean, it becomes clear that at the beginning of summer, large ice-free areas formed both at the northern edge of the Ross Sea and in a region spanning from the eastern edge of the Weddell Sea to the coast of East Antarctica. In contrast, off the coast of West Antarctica and Adélie Land, and to the east and west of the Antarctic Archipelago, sea-ice satellites detected significantly more ice floes than the long-term mean in October 2024 (Figure 9).
It remains to be seen how the summertime melting will continue in the Antarctic. In the record low year 2023, the melting lost a bit of momentum toward the end of the year (Figure 8); the next eight weeks will show whether or not this trend is repeated.
No new Marine Protected Areas in the Antarctic
In contrast, the outcome of this year’s meeting of the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), held from 14 to 25 October in Hobart, Australia, is already perfectly clear. At the event, the 27 member states once again deliberated on the creation of new Marine Protected Areas in the Southern Ocean. The discussions focused on proposals for new Protected Areas in the Weddell Sea, near the western Antarctic Peninsula, and in the waters off of East Antarctica. But once again, Russia and China vetoed the proposed additions. Since the CCAMLR’s resolutions have to be unanimous, this year’s deliberations of the Antarctic Commission ended without producing any concrete results. For years now, experts from the Alfred Wegener Institute have supported the German federal government’s proposal to establish a Marine Protected Area in the Weddell Sea.
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