Arctic Sea Ice Thickness Maps

Arctic sea ice thickness processed at UCL from CryoSat's SAR mode data

Note that sea ice thickness is not calculated from CryoSat during the Arctic summer months (May-Sep) due to measurement problems caused by melt ponds on the sea ice.

Latest from Near Real Time Data

Final Precise Data

2-days 14-days 28-days

Latest 5km Grid of 28-day Thickness : 7/1/24 - 3/2/24

DATA

NRT

Click in map for
local and basin thickness
time series

Note that the 2, 14 and 28-day sea ice thickness maps are processed from CryoSat Near Real Time (NRT) data. These are preliminary fast access products which do not use all the precise corrections available in the final products, available 30 days later. The archive of monthly sea ice thickness products use the precise final CryoSat data as soon as it is available.

Product Format

The data format and further information on the sea ice thickness product can be found in this document:

CPOM_CS2_Operational_Formats_v1.5.pdf

When using this data please cite: Tilling et al, 2018 https://doi.org/10.1016/j.asr.2017.10.051

How is Sea Ice Thickness derived from CryoSat?

CryoSat uses a synthetic aperture radar to sample a much smaller footprint than previous satellite radar altimeters. This allows us to discriminate between sea ice floes and ocean leads with confidence which, in turn, means we can measure their shape.

From this, we can compute sea ice thickness and volume using independent measurements of the ice age, density, and snow loading.

This measurement technique works in autumn, winter and spring. In summer, melt ponds prevent us from estimating sea ice thickness

Arctic Sea Ice Time Series

Display the change over time in sea ice thickness or volume over the whole Arctic, an ocean basin, or thickness at a point location:

The plot below shows the timeseries of Monthly mean sea ice thickness calculated from CryoSat precise and near real time (NRT) data over the whole Arctic area of sea ice extent.

Whole Arctic Thickness

DATA

A timeseries at a single location and Arctic basin can also be displayed by clicking on the sea ice thickness maps on the left or by entering a latitude and longitude location and choosing Select by Point in the panel above.

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 CryoSat-2 record.

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 CryoSat-2 record.

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 thermodynamic growth.

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 2011-2020).

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 March�April 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.

Report Date: Mar-2018

On March 17 2018 the US National Snow and Ice Data Centre (NSIDC) called the maximum extent for the year of 14.48 million square kilometres (5.59 million square miles). This was the second lowest of the 39-year passive microwave satellite record behind March 2017. The Arctic sea ice volume from CryoSat-2 (24,160 cubic kilometres) was just 20 cubic kilometres greater than 2017, so tied as the lowest volume of the 8-year radar altimeter record. MYI volume in March 2018 was 2,000 cubic kilometres smaller than 2017, associated with a reduction in the spread of MYI north of the Canadian Archipelago. This deficit was balanced by a rapid growth in FYI volume over the sea ice growth season, with average ice thickness in the Siberian Shelf Seas 18 cm thicker than in March 2017.

Report Date: Oct-2017

Sea ice volume at the end of summer 2017 was comparable with that of 2014 (7,400 and 7,600 cubic kilometres�respectively) - the second highest volume of the CryoSat-2 record after 2013 (9,000 cubic kilometres). In both 2017 and 2014 the average sea ice thickness in October was 120 cm, with an ice extent around 6 million square kilometres. However, the ice volume lost over summer 2017 was 4,400 less than 2014 due to a smaller volume at the start of summer and smaller reduction in the area of the oldest MYI cover. The US National Snow and Ice Data Centre (NSIDC) report that the rate of ice loss over summer 2017 was slowed by a persistent pattern of low sea level pressure over the central Arctic Ocean.

Report Date: Mar-2017

For the third year running, Arctic sea ice reached a record low maximum extent in March. The US National Snow and Ice Data Centre (NSIDC) reported that the extent of Arctic sea ice reached just 14.42 million square kilometres on March 7th. CryoSat data show that this coincided with a record minimum amount of sea ice for March of 24,200 cubic kilometres, despite the ice cover being as thick as the previous year - 178 cm, on average - and thicker than in 2012 or 2013.

Once Arctic sea ice has reached its maximum area for the year it can continue to thicken as seawater beneath the ice freezes to the under-ice surface, meaning the ice cover reaches its maximum annual amount towards the end of March or start of April. Therefore, it is currently too early to say exactly how this years maximum ice amount will compare to previous years.

Report Date: Feb-2017

February data show that although Arctic sea ice covered the smallest area on record for the time of year, it was thicker (165 cm on average) than in February 2012 or 2013. As a result, the volume (22,000 cubic kilometres) was not the record winter low that might be expected; instead levels were very similar to those of 2012. Centre for Polar Observation and Modelling (CPOM) Researcher Rachel Tilling explained: "This is likely to be the continued effect of 2013's cool summer, when lower levels of melting boosted the winter ice cover: winter 2014 saw a big jump in both thickness and volume, but they have been declining since."

Report Date: Jan-2017

CryoSat data for January show that Arctic sea ice was thicker this year than in the years spanning 2010-2013, and also last year in 2016. However, the sea ice extent was the smallest on record for January and this is reflected in the total amount of ice, which at 18,400 cubic kilometres was the second lowest on record following 2013.

Report Date: Dec-2016

Following the joint record low in November Arctic sea ice volume, which was associated with a low ice extent and slow early winter growth, the amount of ice measured by CryoSat in December was higher than in the years spanning 2010-2012. Despite the extent of the ice cover remaining low, the ice thickness - 135 cm, on average - exceeds that of 2010, 2011 or 2012. This is due to comparatively thicker ice being present in the multiyear ice (MYI) region surrounding the north coast of Greenland and the Canadian Archipelago.

Report Date: Nov-2016

Lowest early-winter sea ice growth on record

There is set to be only 10,500 cubic kilometres of sea ice in the Arctic this month - the joint lowest of any November on record - according to satellite observations processed by the UK's Centre for Polar Observation and Modelling (CPOM). Although sea ice volume did not hit a record low at the end of summer, due to the ice being thicker than in most other years, the early winter growth has been 9% slower than usual and has led to today's conditions.

The measurements were made using the European Space Agency's CryoSat satellite, which is dedicated to monitoring the polar regions and is uniquely able to detect the thickness of sea ice floes. Not only are these observations vital for tracking climate change, they are also an essential resource for maritime operators who increasingly navigate ice infested waters.

The minimum extent of Arctic sea ice on September 10th (4.1 million square kilometres) tied with 2007 as the second lowest on record, although CryoSat showed that the ice was thicker at the end of summer than in most other years and so there was substantially more ice than in two other years (2011 and 2012).

CPOM Research Fellow Rachel Tilling explained, “Sea ice is highly mobile and susceptible to deformation, so we need to measure its thickness as well as its extent to be sure how much is there.” However, although the Arctic sea ice pack usually gains 161 cubic kilometres per day in November, this year's growth has been 9% lower at 139 cubic kilometres per day, and it is estimated that the final amount will rise to only 10,500 cubic kilometres by the month end.

This would essentially tie with conditions in the Novembers of 2011 and 2012, when levels of Arctic sea ice were at their lowest on record for this time of year. Although sea ice in the central Arctic is currently thicker than it was in 2011 and 2012, there is far less ice in more southerly regions such as the Beaufort, East Siberian and Kara Seas. Rachel Tilling added: “Because CryoSat can measure Arctic sea ice thickness in autumn, it gives us a much clearer picture of how it has fared during summer. Although sea ice usually grows rapidly after the minimum extent each September, this years’ growth has been far slower than we’d expect – probably because this winter has been warmer than usual in the Arctic.” As demand for information on Arctic conditions increases, CryoSat has become an essential source of information for polar stakeholders ranging from ice forecasting services to scientists studying the impacts of climate change. CPOM Director and Principal Scientific Advisor to the CryoSat mission, Professor Andrew Shepherd, summarised: “In its’ short, six years of life, we have learnt more about Arctic sea ice from CryoSat than from any other satellite mission. But to really understand the role that sea ice plays in the climate system, and the restrictions it places on maritime operations, we must ensure that its measurements are continued into the future.” A complete assessment of 2016 sea ice conditions will be available from CPOM in the coming weeks.

Report Date: Oct-2016

This year, the US National Snow and Ice Data Centre (NSIDC) reported that the extent of Arctic sea ice fell to 4.1 million square kilometres on September 10th - tied with 2007 as the second lowest on record. However, CryoSat shows that the ice was thicker at the end of summer than in most other years - 116 cm, on average. Therefore, at 6,300 cubic kilometres there was substantially more ice than in two other years (2011 and 2012). Thicker ice can occur if melting is lower, or if snowfall or floe-compaction is higher.

Report Date: Sep-2016

Winter 2015/16 saw the lowest maximum Arctic sea ice volume recorded by CryoSat since its launch in 2010 (approximately 24,500 km3). This "minimum maximuma" coincided with the one of the lowest annual maximum ice thicknesses on record of 183 cm in Aoril.

Following the summer melt period, according to the US National Snow and Ice Data Centre (NSIDC) on 10 September 2016 the Arctic sea ice covered 4.14 million square kilometres, tied with 2007 as the second lowest in the satellite record.Measurements of ice extent or area however only give a two-dimensional view of the Arctic, whereas volume - which combines extent with ice thickness - provides a much more reliable estimate of how much ice remains. Although the minimum sea ice extent is reported in September, the ice continues to thin for another month, meaning that the minimum volume will occur in October. This year's low sea ice extent nonetheless suggests that 2016's summer volume will also be one of the lowest on record.

The final figure will however be affected by the nature of 2016's Arctic summer. Previous CPOM research has already demonstrated that lower summer temperatures can allow thicker sea ice to persist as there are fewer days when it can melt, and reports from NSIDC of cooler weather north of Russia may mitigate against a record minimum. Further data is nonetheless needed to establish whether there is a long-term downward trend in ice thickness and volume, highlighting the need for continued observations. A comprehensive assessment of 2016 sea ice volume will be available from CPOM in the coming weeks.

Report Date: Mar-2016

Thin sea ice observed following record low winter extent

This year the winter maximum Arctic sea ice area was the lowest on record, reaching just 14.52 million square kilometres on March 24th according to the US National Snow and Ice Data Centre. At 1.8 m on average the ice is also relatively thin, similar to that measured in 2012 and 2013, and so the total amount looks similar to the record low of 2013 when there was 24,800 cubic kilometres of ice at peak. To understand how the total amount of Arctic sea ice is changing we need to combine area measurements with thickness. Sea ice thickness can now be measured using data from the European Space Agency CryoSat-2 satellite, which was launched in 2010.

It is currently too early to say exactly how this years maximum ice amount will compare to previous years because Arctic sea ice continues to thicken after it has reached its maximum area. - Once Arctic sea ice has reached its maximum area for the year it continues to thicken for about a month as seawater beneath the ice freezes to the under-ice surface. We expect the ice to reach its maximum amount towards the end of March or start of April - explained Rachel Tilling, a sea ice researcher at the Centre for Polar Observation and Modelling (CPOM) at University College London. This year there is still a lot of thick, older ice north of Canada and Greenland. But there is less of the thinner, newer ice in regions like the Beaufort and Barents Seas. The thickening of ice in March this year has been unusually slow. "So far the ice has only thickened by about 8 cm since February, when usually it thickens by twice this amount" says Tilling. The slow thinning and absence of new ice could be due to warmer air temperatures over the Arctic, which in February were an average of 5 degs C higher than the 2003-2015 average [airs.jpl.nasa.gov]. CPOM Director Professor Andy Shepherd says "because we now have a relatively low amount of ice going in to summer, we can expect the summer minimum to be low too."

Report Date: 26-Oct-2015

Maps of Arctic sea ice thickness are again available in near real time from the Centre for Polar Observation and Modelling, based on measurements acquired by the European Space Agency's CryoSat-2 satellite mission. This operational dataset, which aids maritime activities in ice infested waters and improves scientific understanding of the Polar Regions, has been paused since May because melt ponds on sea ice hamper the detection of sea ice thickness during summer.

Measurements of sea ice thickness are now available for the first two weeks of October 2015, and a snap estimate puts the volume of Arctic sea ice at approximately 6200 km3 in the wake of this year’s melting season. This latest reading suggests that there has been a progressive decline in autumn Arctic sea ice volume following the sharp increase that occurred in 2013, and conditions are now similar to those observed back in 2010. A complete picture will be available in the coming weeks once CryoSat-2 has been able to survey the entire Arctic.

The volume of Arctic sea ice at the end of this summer is the fourth lowest recorded by CryoSat-2 during its 6-year mission . This is consistent with the minimum extent reported in September by a National Snow and Ice Data Centre report, which at 4.41 million km2 was also the fourth lowest of the last 6 years, and in fact since 1979 when records began. Changes in sea ice volume and extent don't always go hand in hand. However, this year they have, and it is likely that above average air temperatures in the Arctic this summer have driven changes in Arctic sea ice volume and extent.

Sea Ice Volume and Thickness

Arctic Sea Ice Thickness Maps

Product Format

How is Sea Ice Thickness derived from CryoSat?