Report Date: Dec-2020
Sea Ice Volume
The total volume of Arctic sea ice in December 2020 was 14.15 thousand cubic kilometres, the
lowest December volume over the CryoSat-2 record (2010-present). Due to rapid growth between
November and December, the volume of seasonal ice this month (9.16 thousand cubic kilometres)
was above the 2010-2020 average (9.12 thousand cubic kilometres). Continuing the trend of the
previous months, multi-year ice volume for this month was the 3rd lowest since the start of the
Sea ice extent for this month was the second lowest of the decade after 2016, at 11.05 million
square kilometres. With first-year ice extent being above average for this month, the overall
low extent is dominated by reduced multi-year ice extent, which was 3rd lowest over the
Volume increased from 9.86 to 14.15 thousand cubic kilometres (43%) between November and
December 2020. The magnitude of November to December volume increase was higher than the
previous few years but there is little trend over the last decade, suggesting that any delay to
freeze-up has been compensated for by December.
Sea Ice Thickness
Average sea ice thickness for December 2020 was 1.28 metres, the fourth lowest over the
CryoSat-2 record and below the 2010-2020 average of 1.35 metres. Negative anomalies in the
multi-year ice pack north and east of Greenland have persisted since October; multi-year ice
that starts the season anomalously thin will remain so, since multi-year ice is generally of a
thickness which prevents thermodynamic growth. Ice is thicker than average in the Beaufort sea
and north of Alaska, where cooler than average air temperatures may have promoted increased
Report Date: Nov-2020
Sea Ice Volume
The total volume of Arctic sea ice in November 2020 was 9.86 thousand cubic kilometres, the
lowest over the CryoSat-2 record (Nov 2010-). Following the October 2020 record-low, reduced
November volume was the result of delayed freeze-up of the Arctic ice pack, with the volume and
thickness of first-year ice both at their lowest on record. Extent for this month (8.67 million
square kilometres) was the second lowest since 2011 after 2016, with the extent of first-year
and multi-year ice both below average.
Volume doubled from 4.90 thousand cubic kilometres between October and November 2020 owing to
rapid growth in the extent of Arctic sea ice during the freeze-up season. The magnitude of
October to November volume increase has increased since 2011, driven by more rapid growth of ice
extent. The lengthening of the Arctic ice-free season and delayed winter freeze-up means the ice
cover tends to grow more rapidly as the ocean rapidly releases heat when the air temperature
falls. Despite the increase in volume and extent growth, the rate at which sea ice thickens
between October and November has declined since 2011, which is likely the result of increased
air temperatures and reduced thermodynamic growth.
Sea Ice Thickness
Average sea ice thickness for November 2020 was 1.14 metres, the second lowest over the
CryoSat-2 record after October 2011 (1.13 m). Most of the November sea ice pack shows a negative
thickness anomaly compared to the 2011-2021 average, in line with increased air temperatures
compared to the long-term mean. Sea ice north of Canada and in the Beaufort Sea was thicker than
usual, potentially due to enhanced dynamic growth resulting from anomalously low sea level
pressure across the Arctic Ocean during this month and a strengthened Beaufort Gyre.
Report Date: Oct-2020
Sea Ice Volume
The total volume of Arctic sea ice in October 2020 was 4.96 thousand cubic kilometres, the
lowest over the CryoSat-2 record (Oct 2011-). Extent for this month (4.87 million square
kilometres) was also the lowest since 2011, and 1 million square kilometres below the 2011-2020
average of 5.87 million square kilometres.
This record-low volume is mainly due to the loss of first-year ice, the volume and extent of
which was also at its lowest since 2011. Multi-year ice volume was the third lowest since 2011
despite above-average ice extent this month (3.40 vs 3.32 million square kilometres average for
Sea Ice Thickness
Average sea ice thickness for October 2020 was 1.02 metres, the second lowest over the CryoSat-2
record after October 2011 (0.91 m). Most of the October sea ice pack shows a negative thickness
anomaly compared to the 2011-2020 October average, with losses north of the Canadian Archipelago
exceeding one metre. Anomalously thin sea ice at the start of this season is potentially linked
to warmer than average air temperatures over the Arctic Ocean this month. The regions showing
the strongest negative thickness anomalies, north of Greenland and the Canadian Archipelago,
have experienced air temperatures this month 4 to 5C above average.
Report Date: Apr-2020
This month, average Arctic sea ice thickness was 1.93m - the fourth highest over the CryoSat-2 record. Following the trend of the previous month, positive ice thickness anomalies can be seen in the eastern Chukchi Sea, in the Kara Sea and northeast of Svalbard, with ice more than 1m thicker than the 2011-2020 average in places. Over recent years, ocean temperatures in the Barents and East Greenland Sea have cooled due to reduced import of warm water from the North Atlantic. Cooler than average ocean temperatures promote enhanced sea ice thermodynamic growth in this region, as well as allowing the sea ice margin to move further southward. Air temperatures for this month were warmer than average over most of the Arctic Ocean.
The total volume of Arctic sea ice in April 2020 was 25.13 thousand cubic kilometres, the fourth highest over the CryoSat-2 record (2011-) and slightly above the decadal (2011-2020) April average of 25.01 thousand km3. This above average volume is attributable to a higher volume of first year ice (FYI); the volume of FYI was 19.09 thousand cubic kilometres, the second highest after 2012. The volume of multi-year ice (MYI) however was the fourth lowest since 2011, illustrating the ongoing shift of the Arctic ice pack from a MYI to FYI regime.
Between March and April 2020, volume slightly increased by 0.57 thousand cubic kilometres (2%). This is unusual (volume typically decreases between these months), and is attributable to an average thickness increase of 17cm, the largest MarchżApril thickness change over the CryoSat-2 record.
Report Date: Mar-2020
Average sea ice thickness for March was 1.75m, the third lowest over the CryoSat-2 record after 2013 (1.70) and 2012 (1.73). Ice continues to be +1m thinner than the 2011-2020 average just north of the Ellesmere Island in the Canadian Archipelago. Positive thickness anomalies are apparent north and east of Svalbard, potentially linked to air temperatures being 6C lower than average in this region. Air temperatures were also anomalously low over the western Canadian Archipelago where ice was thicker than average. Thick ice in this region of the Eastern Chukchi Sea could also be the result of dynamic growth; it was reported that a series of storms this month caused sea ice to pile up along the coast and form large pressure ridges.
The total volume of Arctic sea ice in March 2020 was 24.56 thousand cubic kilometres, the fifth lowest over the CryoSat-2 record (2011-). January and February were both the second lowest volumes since 2011, therefore between February and March the sea ice pack seems to have recovered to more average values, possibly aided by lower than average temperatures over much of the Arctic Ocean this month. Total volume for this month was still below the decadal March average (2011-2020) of 25.15 thousand cubic kilometres. Volume increased by 2.94 thousand cubic kilometres (14%) between February and March 2020. The magnitude of February to March volume increase has slightly but not statistically significantly decreased since 2011, a result of slightly increasing rate of thickening and slightly decreasing extent growth rate.
Report Date: Feb-2020
Average sea ice thickness for February was 1.56m, the second lowest over the CryoSat-2 record after February 2013 (1.48). The negative thickness anomaly in the multi-year ice region north of the Canadian Archipelago has become less pronounced compared to the previous month, which could be due to cooler temperatures in this region in January and February 2020. As in January, ice was thicker than average in the Barents and Kara Seas which could be linked to persistent anomalously low pressure promoting stronger winds and increased dynamic growth.
The total volume of Arctic sea ice in February 2020 was 21.62 thousand cubic kilometres, the second lowest over the CryoSat-2 record (2011-) after 2013 (20.82 thousand cubic kilometres). Extent for this month was above average (highest extent since 2013), therefore the low sea ice volume is attributable to a thinner than average ice pack. Volume increased by 3.61 thousand cubic kilometres (20%) between January and February 2020. The magnitude of January to February volume increase has slightly but not statistically significantly increased since 2011, as have thickness change and extent increase.
Report Date: Jan-2020
Average sea ice thickness for January was 1.40m, the second lowest over the CryoSat-2 record after January 2013 (1.39m). The most prominent negative thickness anomaly was in the multi-year ice region north of the Canadian Archipelago, with losses exceeding 1m compared to the 2010-2019 January average. Ice has been thinner than average in this region since the start of freeze-up in October 2019, potentially linked to anomalously warm air temperatures in November and December 2019. Ice was thicker than average in the Barents and Kara Seas which could be linked to anomalously low pressure promoting stronger winds and increased dynamic growth.
The total volume of Arctic sea ice in January 2020 was 18.01 thousand cubic kilometres, the second lowest over the CryoSat-2 record (2011-) after 2013 (only 22 cubic kilometres less at 17.99 thousand cubic kilometres). Extent for this month was above average (4th highest extent since 2011), therefore the low sea ice volume is attributable to a thinner than average ice pack. Volume increased by 3.57 thousand cubic kilometres (25%) between December 2019 and January 2020. The magnitude of December to January volume increase has declined since 2010, driven by a reduction in ice thickening (extent increase has remained relatively consistent). Thickness growth between December and January has declined from ~20cm in 2010 to ~10cm in 2019, which could be a result of warmer air temperatures and reduced thermodynamic growth, or reduced dynamic thickening.