Throughout February, Arctic sea ice extent tracked between second and fourth lowest in the satellite record while Antarctic sea ice extent tracked at record low extents. Antarctic sea ice has hit its minimum extent for the year, setting a new record low, and is now expanding.

Overview of conditions

Figure 1a. Arctic sea ice extent for February 2023 was 14.18 million square kilometers (5.47 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Figure 1b. The graph above shows Arctic sea ice extent as of March 1, 2023, along with daily ice extent data for four previous years and the record high year. 2022 to 2023 is shown in blue, 2021 to 2022 in green, 2020 to 2021 in orange, 2019 to 2020 in brown, 2018 to 2019 in magenta, and 2011 to 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

The February 2023 average Arctic sea ice extent was 14.18 million square kilometers (5.47 million square miles), the third lowest February in the satellite record (Figure 1a). February extent was 1.12 million square kilometers (432,000 square miles) below the 1981 to 2010 average of 15.30 million square kilometers (5.91 million square miles), but 210,000 square kilometers (81,000 square miles) above the record low set in February 2018.

The overall daily rate of increase in extent through the month was near average, but with periods of rapid increase at the start and the middle of the month, followed by periods of little change (Figure 1b). This is not uncommon for this time of year as ice growth slows and the ice edge is vulnerable to winds that either compress or expand the ice cover. Ice expansion slowed the last week of February and while the seasonal maximum does not appear to have been reached, it is likely not far away. The seasonal maximum has occurred as early as February 24 in 1987 and 1996 and as late as April 2 in 2010.

Overall, extent increased 724,000 square kilometers (280,000 square miles) during February 2023, compared to the 1981 to 2010 average February increase of 573,000 square kilometers (221,000 square miles). Regionally, extent remained below average in the Barents Sea, the Sea of Okhotsk, and the Gulf of St. Lawrence. In the Bering Sea, the ice extent was closer to average.

Conditions in context

Figure 2a. This plot shows average sea level pressure in the Arctic in millibars for February 2023. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for February 2023. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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During February, the Arctic Oscillation, a large-scale mode of Arctic climate variability, was in a strongly positive phase. When the Arctic Oscillation index is positive, the low sea level pressure over Svalbard strengthens, and the winds circulating around the North Pole are stronger, helping to keep cold air in the Arctic Ocean. The sea level pressure pattern for February featured unusually low sea level pressure over Svalbard coupled with high pressure over the central Arctic Ocean and Siberia (Figure 2a). The Siberian High and Beaufort Sea High are common features of winter, yet this February, the Beaufort Sea High shifted more towards the Pole. The combination of low pressure over Svalbard and high pressure over the central Arctic Ocean helped drive relatively warm air from the south across the North Atlantic and into the Barents Sea, and push cold Arctic air towards the Bering Sea. Cold Arctic air was also drawn westwards into eastern Canada. Air temperatures of up to 6 degrees Celsius (11 degrees Fahrenheit) below average  were also found over Baffin Bay and Hudson Bay (Figure 2b).

Another noteworthy atmospheric event of February was a sudden stratospheric warming (SSW). These occur when atmospheric longwaves propagate into the stratosphere, weakening or even reversing the stratospheric polar vortex. The effects can then propagate downward into the troposphere, enabling cold Arctic air to spill into lower latitudes. Heading into February, it appears that the stratospheric vortex was already in a weakened state because of vertical wave propagation. This made it susceptible to further breakdown about 10 days later when the vortex center shifted from the pole toward Europe. Overall, SSW events generally lead to Arctic sea ice growth, though the exact response varies by region.

February 2023 compared to previous years

Figure 3. Monthly February ice extent for 1979 to 2023 shows a decline of 2.8 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend in February sea ice extent over the 45-year satellite record is 42,300 square kilometers (16,300 square miles) per year, or 2.8 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, February extent has lost 1.86 million square kilometers (718,000 square miles) of ice. This is equivalent to about seven times the size of Colorado or about five times the size of Germany.

The role of atmospheric rivers in keeping Arctic winter sea ice extent low

Figure 4. This figure shows November to January averaged trends in atmospheric river (AR) events. The Arctic map (a) shows AR frequency trend from the ERA5 model and two other climate re-analyses. The plot (b) shows a time series of ARs in the Barents and Kara Seas from three different atmospheric reanalysis data sets together with the sea ice area in that region. AR frequency refers to the number of atmospheric river events in the late-fall/early-winter period; ABK (Arctic-Barents-Kara) refers to the area outlined in red in the map, and SIA is sea ice area.

Credit: Zhang et al., 2023
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In recent years, low sea ice extent in the Barents and Kara Seas has driven the overall negative trend in winter Arctic sea ice. Previous studies attributed the low ice cover in this region to increased ocean heat transport from the North Atlantic. A new study is looking at the role of atmospheric rivers as a contributing process. Atmospheric rivers bring in warm moist air from the tropics and subtropics, increasing the downward longwave radiation to the surface. They can also bring heavy rainfall. Both processes can melt sea ice. According to the study, more atmospheric rivers are entering the Eurasian Arctic than previously, leading to reduced ice formation or melting of thin ice in November through January.

The Kivalliq polynya

Figure 5. This NASA Visible Infrared Imaging Radiometer Suite (VIIRS) visible image was taken on February 6, 2023. The darker area on the western half of the Bay is newly formed sea ice where the polynya opened.

Credit: The National Oceanic and Atmospheric Administration Cooperative Institute for Meteorological Satellite Studies (CIMSS) at the University of Wisconsin-Madison Satellite Blog
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Hudson Bay is generally completely ice covered during the Arctic winter. However, as in other places, polynyas, regions of persistent open water, can occur under certain conditions. In western Hudson Bay, openings and closings of what is called the Kivalliq polynya are regular events related to strong winds. This polynya forms in winter as offshore winds push the ice away from the coast. As ice is pushed away, the open water left behind begins to freeze and new ice quickly forms. On average, about 182 cubic kilometers (43.7 cubic miles) of new ice is produced annually in this polynya, equivalent to about 20 percent of the winter ice volume of Hudson Bay, according to colleagues at the University of Manitoba. On January 21, the Kivalliq polynya once again opened and was soon covered by thin ice that was observed in visible and thermal satellite imagery. Synthetic Aperture Radar (SAR) and L-band passive microwave data from the Soil Moisture and Ocean Salinity (SMOS) satellite also captured the opening and closing of the polynya. Interestingly, the ice reflectance and the surface temperature in this region two weeks later was quite uniform, suggesting very uniform ice thickness (Figure 5). Polynyas such as this one not only facilitate ice production, they are also biologically important regions, fostering springtime phytoplankton blooms. They also play a large role in heat and moisture exchanges between the ocean and the colder atmosphere above it. Moreover, they lead to the production of dense, cold, and salty water as the sea ice freezes. Sea ice crystals are fresh ice and the formation of the crystals reject the salt brine, leading to dense descending water.

Antarctic sea ice may be reversing course

Figure 6a. Antarctic sea ice extent for February 2023 was 1.90 million square kilometers (734,000 square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Figure 6b. Antarctic sea ice concentration for February 2023 was 1.20 million square kilometers (463,000 square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Antarctic sea ice extent continued to track at record lows for this time of year. By the end of February, extent was 1.83 million square kilometers (707,000 square miles). This is 93,000 square kilometers (35,900 square miles) below the record seasonal minimum that occurred on February 25, 2022. Extent remained particularly low in the Amundsen, Bellingshausen, and Ross Seas (Figure 6a). Most of the sea is ice gone from the Ross Sea, and what little ice remains in the Amundsen/Bellingshausen Seas is very low concentration (Figure 6b). In the Weddell Sea, the ice edge remains near average for this time of year.

Until recently, there was a weak overall upward trend in Antarctic sea ice extent, but with some parts of the Antarctic sea ice exhibiting strong positive trends in extent and other areas exhibiting strong negative trends. According to colleagues at Commonwealth Scientific and Industrial Research Organisation (CSIRO Australia), this pattern is changing. Over the past decade, there is less regional variability. Patterns of sea ice extent variations, high or low, have become more uniform around the continent. This has contributed to the lower Antarctic sea ice extents that have been observed since 2016.

References

Bruneau, J., D. Babb, W. Chan, S. Kirillov, J. Ehn, J. Hanesiak, and D. G. Barber. 2021. The ice factory of Hudson Bay: Spatiotemporal variability of the Kivalliq Polynya. Elementa: Science of the Anthropocene, 9, (1). doi:10.1525/elementa.2020.00168.

Schroeter, S., T. J. O’Kane, and P. A. Sandery. 2023. Antarctic sea ice regime shift associated with decreasing zonal symmetry in the Southern Annular Mode. The Cryosphere, 17, 701–717, doi:10.5194/tc-17-701-2023.

Smith, K. L., L. M. Polvani, and L. B. Tremblay, L. B. 2018. The Impact of Stratospheric Circulation Extremes on Minimum Arctic Sea Ice Extent. Journal of Climate, 31(18), 7169-7183. doi:10.1175/JCLI-D-17-0495.1.

Zhang, P., G. Chen, M. Ting, et al. 2023. More frequent atmospheric rivers slow the seasonal recovery of Arctic sea ice. Nature Climate Change. doi:10.1038/s41558-023-01599-3.

Daily extent of Arctic sea ice for December 2022 remained well below average for the entire month; at the end of the month, extent stood at fourth lowest in the satellite record. The average extent for the month ended up as seventh lowest in the satellite record. Antarctic extent is declining much faster than average as austral summer takes hold and is setting record low daily ice extents for the satellite era as of December 22. As such, global sea ice extent is well below average.

Overview of conditions

Figure 1a. Arctic sea ice extent for December 2022 was 11.92 million square kilometers (4.60 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Figure 1b. The graph above shows Arctic sea ice extent as of January 4, 2023, along with daily ice extent data for four previous years and the record low year. 2022 to 2023 is shown in blue, 2021 to 2022 in green, 2020 to 2021 in orange, 2019 to 2020 in brown, 2018 to 2019 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

The average Arctic sea ice extent for December 2022 was 11.92 million square kilometers (4.60 million square miles). This is the seventh lowest in the satellite record for the month (Figure 1a). Extent was 920,000 square kilometers (355,000 square miles) below the 1981 to 2010 average of 12.84 million square kilometers (4.96 million square miles) and 460,000 million square kilometers (178,000 square miles) above the record December low set in 2016 of 11.46 million square kilometers (4.42 square miles).

The rate of ice growth through the month was variable. It was faster than average through the first half of the month, then growth slowed, and then picked up the pace again. Over the last week of the month, ice growth was very slow, and as a result, total extent at the end of December stood at fourth lowest in the satellite record (Figure 1b). Regionally, at month’s end, the ice edge was notably north of its average location in the Barents Sea and on the Russian side of the Bering Sea. Hudson Bay is now almost completely iced over.

Conditions in context

Figure 2a. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for December 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2b. This plot shows average sea level pressure in the Arctic in millibars for December 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Average December air temperatures at the 925 hPa level (approximately 2,500 feet above the surface) were above the 1991 to 2020 average over essentially all of the Arctic Ocean, but notably in the area centered over the East Siberian Sea (Figure 2a). The unusually warm conditions in this area, which were 6 to 8 degrees Celsius (11 to 14 degrees Fahrenheit) above average, appear to be related to the large area of below-average sea level pressure over the northern North Pacific Ocean pumping warm air into the East Siberian Sea (Figure 2b). Air temperatures were also above average over the eastern Canadian Arctic and most of Greenland.

December 2022 compared to previous years

Figure 3. Monthly December ice extent for 1978 to 2022 shows a decline of 3.5 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend in December sea ice extent over the 45-year satellite record is 44,400 square kilometers (17,100 square miles) per year, or 3.5 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1978, November has lost 2.28 million square kilometers (880,000 square miles). This is equivalent to about 1.5 times the size of Alaska.

The year in review

Figure 4a. The graph above shows Arctic sea ice extent for 2022 (blue line) and 2012, the record minimum year (dashed red line). The gray line shows the 1981 to 2010 median, the dark gray shaded area shows the interquartile range, and the light gray shaded area shows the interdecile range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 4b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for summer 2022 from June 1 to August 31. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 4c. This plot shows average sea level pressure in the Arctic in millibars for summer 2022 from June 1 to August 31. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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While Arctic sea ice extent was below average over the entire year (Figure 4a), no records were set, and the September average sea ice extent, at 4.87 million square kilometers (1.88 million square miles), tied with 2010 as only the eleventh lowest in the satellite record. The September daily minimum extent, set on September 18 at 4.67 million square kilometers (1.80 million square miles), tied with 2017 and 2018 for tenth lowest in the satellite record. The September minimum extent is strongly dependent on summer weather conditions, and summer average air temperatures, while above climatological averages over most of the Arctic Ocean, were not extreme (Figure 4b), generally from 1.5 to 2.5 degrees Celsius (3 to 4.5 degrees Fahrenheit) above the 1991 to 2020 baseline. The summer average sea level pressure pattern was in turn quite flat, meaning light winds. A pronounced Beaufort Sea High, which generally favors low September sea ice extent, is notably lacking (Figure 4c).

Ice down under

Figure 5a. This map from January 3, 2023, shows a large polynya that now spans the Ross Sea and much of the western Amundsen Sea, as well as polynyas that have appeared in Pine Island Bay and the southeastern Weddell Sea. Sea ice concentration data are from the Japan Aerospace Exploration Agency Advanced Microwave Scanning Radiometer 2 (AMSR2) imagery.

Credit: University of Bremen
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Figure 5b. This plot shows the departure from average air temperature in the Antarctic at the 925 hPa level, in degrees Celsius, for November and December 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

Summer is taking hold in the Southern Hemisphere. While the decline in Antarctic Sea ice extent is always steep at this time of year, it has been unusually rapid this year, and at the end of December, Antarctic sea ice extent stood at the lowest in the 45-year satellite record. Sea ice extent was more than 500,000 square kilometers (193,000 square miles) below the previous record year of 2018; four of the five lowest years for the last half of December have occurred since 2016. As is evident in sea ice maps prepared by colleagues at the University of Bremen from the Japan Aerospace Exploration Agency (JAXA) Advanced Microwave Scanning Radiometer 2 (AMSR2) data, an extremely large polynya now spans the Ross Sea and much of the western Amundsen Sea. Polynyas have also appeared in Pine Island Bay and the southeastern Weddell Sea (Figure 5a). There are also extensive areas of low sea ice concentration in the Weddell Sea that are likely ready to melt out.

Weather-related causes for the unusually low sea ice extent seem to stem from a band of above-average  temperatures extending from the Weddell Sea westward to the Ross Sea and eastern Wilkes Land (Figure 5b). Air temperatures at the 925 mb level were more than 1 degree Celsius (2 degrees Fahrenheit) above average over the entire area in November and December, and were more than 2 degrees Celsius (4 degrees Fahrenheit) above average over the Ross Sea. The past two months have seen periods of strong circumpolar winds and below-average air pressure over the continent, leading to strong winds from the west across the Peninsula. This has caused melting along the eastern Peninsula ice, above-average air temperatures over the Weddell Sea, and outflowing winds from the continent, opening the polynyas and hastening ice decline. This wind pattern is summarized by the Southern Annular Mode (SAM) index, a measure of the intensity of the circumpolar winds; this has been in a positive phase for most of 2022 and has been quite strong in the last quarter of the year.

As October drew to a close, freezing progressed rapidly in the Laptev Sea. In the Antarctic, where spring is slowly unfolding, overall ice extent is low, with patterns suggesting a strong persistent low atmospheric pressure in the Amundsen Sea.

Overview of conditions

Figure 1a. Arctic sea ice extent for October 2022 was 6.61 million square kilometers (2.55 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Figure 1b. The graph above shows Arctic sea ice extent as of November 2, 2022, along with daily ice extent data for four previous years and the record low year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

The October 2022 average Arctic sea ice extent was 6.61 million square kilometers (2.55 million square miles). This is the eighth lowest in the satellite record (Figure 1a). Extent was 1.74 million square kilometers (672,000 square miles) below the 1981 to 2010 average of 8.35 million square kilometers (3.22 million square miles) and 1.28 million square kilometers (494,000 square miles) above the record minimum set in 2020 of 5.33 million square kilometers (2.06 million square miles).

Ice extent increased at a below average rate at the beginning of the month, and open water persisted for some time in the Laptev Sea, whereas the East Siberian Sea was among the first regions to freeze up. In the last ten days of the month, ice extent rapidly increased (Figure 1b) as the Laptev Sea iced over. The delayed freeze up in the Laptev Sea could be partly a result of ocean heating from the extended period of open water this past spring and summer. However, slow freeze up in this region in recent years is also consistent with observations of eddies within the Arctic Circumpolar Boundary Current that maintain a generally upward ocean heat flux, bringing warm Atlantic water along the eastern Arctic continental slope. The Arctic Circumpolar Boundary Current is a shallow, 200- to 400-meter-deep (660 to 1,300 feet) eastward-flowing current that follows the edge of the continental shelf and carries warm water at 2 to 3 degrees Celsius (36 to 37 degrees Fahrenheit) in shallow depths around the Arctic Ocean. The configuration of the continental shelf in the Russian Arctic brings this water very near the coastal Laptev Sea.

At the end of the month, extent remained below average in the Chukchi Sea on the Pacific side of the Arctic, and also in the Barents and Kara Seas on the Atlantic side.

Conditions in context

Figure 2a. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for October 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2b. This plot shows average sea level pressure in the Arctic in millibars for October 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

Air temperatures during October at the 925 millibar level (approximately 2,500 feet above the surface) were near to above average over most of the Arctic Ocean (Figure 2a). The largest departures from average for this time of year were over the Kara Sea, where air temperatures averaged for October remained above freezing.

The average atmospheric circulation pattern was dominated by below average sea level pressure over nearly the entire Arctic (Figure 2b). Pressures were as much as 10 to 12 millibars below average over the Chukchi and East Siberian Seas and stretching across the pole. This pattern is reflected in the persistence of positive values of the Arctic Oscillation Index for most of the month. When the Arctic Oscillation is in its positive mode, pressures are below average over the Arctic, but above average over the Northern Hemisphere mid latitudes.

October 2022 compared to previous years

Figure 3. Monthly October ice extent for 1979 to 2022 shows a decline of 9.6 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend in October sea ice extent over the 45-year satellite record is 80,400 square kilometers (31,000 square miles) per year, or 9.6 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979 October has lost 3.46 million square kilometers (1.34 million square miles). This equivalent to about twice the size of the state of Alaska.

Arctic sea ice loss may make El Niños more common

Figure 4. These plots show histograms of El Niño indices associated with Arctic sea ice loss experiments in climate model runs. The left histogram (a) shows the zonal sea surface temperature (SST) gradient in the equatorial Pacific that is defined as the average SST over the Niño 3.4 region (5S-5N, 170W-120W) minus the Maritime Continent region (5S-5N, 110E-160E). The histogram on the right (b) shows the meridional SST gradient in the eastern equatorial Pacific that is defined as the average SST over 5N-10N, 160W-100W minus 2.5S-2.5N, 160W-100W. The vertical bars denote 20-year periods of constant Arctic sea ice in experiments using the US National Center for Atmospheric Research Community Earth System Model (CESM). Gray is the historical period (1980 to 1999); blue is the future period of moderate ice loss (2020 to 2039); and red is the future period of seasonally ice-free conditions (2080 to 2099). Each bin represents 0.5 standard deviation of the corresponding SST anomalies or gradients. Black dashed lines represent 1.5 (strong El Niño) and 2 (extremely strong El Niño) standard deviations.

Credit: Jiping Liu et al. 2022, adapted by NSIDC
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El Niño is an important departure in ocean temperatures along the equator, linked to weakened trade winds. During an El Niño, the cold upwelled waters along the coast of the Americas and much of the eastern parts of the tropical Pacific are replaced by warmer water. This can have global impacts on weather, ecosystems, and economies around the world by shifting the Pacific jet stream southwards. In North America, this usually results in drier and warmer conditions than usual in the northern areas, and wetter conditions in the south. While episodes of El Niño typically occur every two to seven years and can last several months to more than a year, climate model simulations by colleagues at the University of Albany suggest that the frequency of El Niño events could increase by 35 percent by the end of this century if the Arctic Ocean loses its summer ice cover.

This link was found to result from increased heat transfer from the ocean to the atmosphere in the absence of sea ice, intensifying low-pressure systems in the Bering Sea (in the area of the Aleutian Low). Lower sea level pressure increases wind speeds that may oppose trade winds, bringing warm western Pacific water towards the east. Another possible mechanism is that as the Arctic Ocean warms from losing its sea ice cover, ocean currents weaken from the south that bring warm water from the eastern Pacific toward the Arctic. Analysis with other climate models is necessary to test the robustness of these connections.

The Antarctic

Figure 5. The graph above shows Antarctic sea ice extent as of November 2, 2022, along with daily ice extent data for four previous years and the record high year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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The seasonal Southern Ocean sea ice maximum extent was reached on September 16, at 18.19 million square kilometers (7.02 million square miles). This was the fourth lowest sea ice maximum in the satellite record, behind 1986, 2002, and 2017. Low sea ice extent has continued to persist, and the springtime decline in austral ice extent has proceeded at an above average pace. At month’s end, Antarctic sea ice was nearing record-low daily ice extents for the date.

Extent is far below average in the Bellingshausen Sea, and far above average in the Amundsen and eastern Ross Seas, a pattern indicative of a strong Amundsen Sea Low. Sea level pressures in the region have been 8 to 12 millibars below average. However, sea ice extent is also low along the Wilkes Land coast, where air temperatures have been 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above average.

Further reading

Aksenov, Y., V. V. Ivanov, A. G. Nurser, S. Bacon, I. V. Polyakov, A. C. Coward, A. C. Naveira‐Garabato, and A. Beszczynska-Moeller. 2011. The Arctic circumpolar boundary current. Journal of Geophysical Research: Oceans. doi:10.1029/2010JC006637.

Liu, J., M. Song, Z. Zhu, et al. 2022. Arctic sea-ice loss is projected to lead to more frequent strong El Niño events. Nature Communications. doi:10.1038/s41467-022-32705-2.

Pnyushkov, A., I. V. Polyakov, L. Padman, and A. T. Nguyen. 2018. Structure and dynamics of mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean. Ocean Science. doi:10.5194/os-14-1329-2018.

The sun is about to set for the winter at the North Pole, and so the 2022 sea ice melt season is coming to an end. As of September 19, 2022, Arctic sea ice extent stood at 4.68 million square kilometers (1.81 million square miles), placing it ninth lowest in the satellite record for the date. The high-latitude polynyas have frozen over.

Overview of conditions

Figure 1. Arctic sea ice extent for September 19, 2022 was 4.68 million square kilometers (1.81 million square miles). The orange line shows the 1981 to 2010 average extent for that day. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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As of September 19, 2022, Arctic sea ice extent stood at 4.68 million square kilometers (1.81 million square miles), placing it ninth lowest in the satellite record for the date. Between September 1 and September 19, the Arctic lost a total of 522,000 square kilometers (202,000 square miles) of ice, at an average rate of 27,500 square kilometers (10,600 square miles) per day. This was slightly faster than the average daily loss rate over this period. As of September 19, sea ice extent was tracking close to the levels observed in 2010, and the spatial pattern of sea ice extent is similar. As seen in Advanced Microwave Scanning Radiometer 2 (AMSR2) imagery, an island, or patch, of apparently fairly thick ice has separated from the main pack in the East Siberian Sea. Another smaller isolated patch is present in the Beaufort Sea. The Northern Sea Route and the southern (Amundsen’s) route through the Northwest Passage remain open and will likely remain so for several more weeks. The northern route through the Northwest Passage still has some scattered areas of pack ice not picked up in satellite passive microwave imagery.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of September 19, 2022, along with daily ice extent data for four previous years and the record low year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, from September 1 to 18, 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2c. This plot shows average sea level pressure in the Arctic in millibars from September 1 to 18, 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Air temperatures over the central Arctic Ocean at the 925 hPa level (about 2,500 feet above the surface), averaged from September 1 through September 18 were from 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above the 1991 to 2020 reference period over most of the North American side of the Arctic, but up to 7 degrees Celsius (13 degrees Fahrenheit) above average over the Greenland Ice Sheet (Figure 2b).

The sea level pressure pattern averaged over the same time period (Figure 2c) was dominated by low pressure extending eastward across Eurasia, Alaska, and into eastern Canada, contrasting with high pressure over the remainder of the Arctic, especially west of Scandinavia and over southern Greenland. The low pressure center over eastern Canada, paired with the high pressure over southern Greenland, has been a somewhat persistent pattern in the first half of September. Winds from the south between the pressure centers and the high average temperature over northern Greenland can be related to the prominent early September melt event over the ice sheet (see Greenland Ice Sheet Today).

A surprising observation

Figure 3. While traveling back from Reykjavik, Iceland, in late August, Arctic Sea Ice News & Analysis contributor Mark Serreze observed a patch of sea ice just off the eastern coast of southern Baffin Island. Small, diffuse patches of sea ice can linger through the summer if conditions are favorable, but they are difficult to detect in satellite imagery.

Credit: Mark Serreze, NSIDC
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While traveling back from the International Glaciological Society International Symposium on Ice, Snow and Water in a Warming World in Reykjavik, Iceland, in late August, Arctic Sea Ice News & Analysis contributor Mark Serreze, while looking for icebergs on the blue ocean out the window of the Iceland Air 757, observed a rather surprising patch of sea ice just off the eastern coast of southern Baffin Island. Such small, diffuse patches—the last remnants of the winter ice pack—can linger through the summer if conditions are favorable, but they are very difficult to detect in satellite imagery.

Arctic sea ice thickness study

Figure 4. This animation shows Arctic sea ice thickness from October 2010 to July 2020. Images are from the European Space Agency’s CryoSat-2, which for the first time include summer sea ice thickness.

Credit: Jack Landy
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A new year-round Arctic sea ice thickness dataset based on observations from the European Space Agency CryoSat-2 mission was released this week. Meltwater ponds accumulating at the ice surface previously prevented researchers from generating valid sea ice thickness data from CryoSat-2 during the summer melt season. Only estimates of sea ice thickness during the Arctic winter growth season were available.

New methods, including deep machine learning and model simulations of the satellite radar altimeter, have now enabled accurate measurements of the sea ice freeboard— the height of the ice above the ocean surface—to be obtained from the archive of CryoSat-2 Arctic summer observations dating back to 2011 (Figure 4, to animate). By accounting for snow that weighs down the sea ice, using data from a snow evolution model available at the NASA National Snow and Ice Data Center Distributed Active Archive Center, the ice freeboards for winter and summer months were converted to a 10-year gap-free sea ice thickness record.

In the study, it was discovered that new CryoSat-2 sea ice thickness observations from the early summer, in May and June, correlate closely with the pan-Arctic sea ice extent in the following September. Through the ice-albedo feedback, the thickness of sea ice floes at the start of the melt season dictate how long they survive during summer. Thick ice floes melt less quickly and can survive for longer, whereas thin ice floes melt away, exposing the darker ocean and accelerating further melt. This demonstrates a strong link between spring sea ice thickness and the end-of-summer sea ice extent.

Antarctic recovery

Figure 5. Antarctic sea ice extent for September 19, 2022 was 18.14 million square kilometers (7.00 million square miles). The orange line shows the 1981 to 2010 average extent for that day. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Antarctic sea extent is nearing it seasonal maximum. While extent was tracking at record or near record lows since early June, there has been a recent spurt in growth, and extent has reached the tenth percentile for this time of year, still well below average but no longer near the record lowest maximum.

Further reading

Landy, J. C., G. J. Dawson, M. Tsamados, M. Bushuk, J. Stroeve, S. Howell, T. Krumpen, D. Babb, A. Komarov, H. Heorton, H. J. Belter, and Y. Aksenov. 2022. A year-round satellite sea-ice thickness record from CryoSat-2. Nature. doi:10.1038/s41586-022-05058-5.

The seasonal decline in Arctic sea ice extent from mid-July onward has proceeded at a near average pace. Extent is currently well below average, but above that observed for recent years. Extent is particularly low in the Laptev Sea sector, but ice extends to near the shore further east. Depending on weather conditions, the southern route through the Northwest Passage may become open. An area of low concentration ice persists over the central Arctic Ocean, extending to near the North Pole, and Antarctic ice extent is still at a record low.

Overview of conditions

Figure 1a. Arctic sea ice extent for August 1, 2022 was 6.99 million square kilometers (2.70 million square miles). The orange line shows the 1981 to 2010 average extent for that day. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Figure 1b. The graph above shows Arctic sea ice extent as of August 1, 2022, along with daily ice extent data for four previous years and the record low year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 1c. This figure shows ice motion vectors at 62.5-kilometer spatial resolution from July 19 to 21, 2022, based on passive and active microwave satellite data from the European Organization for the Exploitation of Meteorological Satellites Ocean and Sea Ice Satellite Application Facilities low-resolution sea ice drift product. Strong on-shore ice motion during the third week of July in part explains the persistence of sea ice in the East Siberian Sea. 


Credit: European Organization for the Exploitation of Meteorological Satellites Ocean and Sea Ice Satellite Application Facilities
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As of August 1, Arctic sea ice extent stood at 6.99 million square kilometers (2.70 million square miles) (Figure 1a). The decline rate of the extent through the second half of July was near the 1981 to 2010 average. Extent on August 1, while well below the 1981 to 2010 average, was the highest since 2014 and overall was twelfth lowest in the satellite record (Figure 1b). The average extent for the month of July as a whole was 8.25 million square kilometers (3.19 million square miles), the twelfth lowest in the satellite record.

As previously reported in our mid-July post, a notable aspect of this summer so far is the substantial amount of open water along the Eurasia Coast in the Laptev Sea sector. However, by sharp contrast, ice is extensive further east in the East Siberian Sea, extending to near the shore. Strong on-shore ice motion during the third week of July in part explains the persistence of sea ice in this region (Figure 1c). Extent continues to be below average in the Barents Sea. The area of low concentration ice over the central Arctic Ocean extending to near the pole persists.

While Russia makes use of the Northern Sea route year-round, over the past decade, this coastal route has become nearly or completely ice-free in late summer. Given the extensive ice in the East Siberian Sea, it seems unlikely that this will be the case in 2022. By contrast, as assessed from Advanced Microwave Scanning Radiometer 2 (AMSR2) satellite data, the southern route through the Northwest Passage, known as Amundsen’s route, may open in the next few weeks, depending on weather conditions.

Conditions in context

Figure 2a. This plot shows average sea level pressure in the Arctic in millibars from July 15 to July 30, 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2b. This plot shows the departure from average air temperature, relative to the 1981 to 2020 reference period, in the Arctic at the 925 hPa level, in degrees Celsius, from July 15 to July 30, 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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The second half of July saw a shift in weather patterns. While the average sea level pressure pattern for the first half of the month featured a distinct area of low pressure centered over the central Arctic Ocean near the North Pole, the pattern for the second half of the month was one of high pressure (an anticyclone) centered north of the Laptev Sea, with low pressure centered near the Bering Strait between eastern Russia and Alaska (Figure 2a). This shift explains both the below average temperatures at the 925 mb level (about 2,500 feet above the surface) over the East Siberian Sea, where the implied winds between the high and low pressures have a component from the north, and the above average temperature north of the Barents Sea, where the implied winds on the eastern side of the anticyclone have an offshore component (Figure 2b).

July 2022 compared to previous years

Figure 3. Monthly July ice extent for 1979 to 2022 shows a decline of 7.2 percent per decade.

Credit: National Snow and Ice Data Center
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Looking at the month as a whole, July sea ice extent declined by 2.42 million square kilometers (930,000 square miles), or at a rate of 78,100 square kilometers (30,200 square miles) per day, which was near the 1981 to 2010 average. This resulted in the average July extent ranking twelfth lowest in the satellite record. The downward linear trend in July sea ice extent over the 44-year-satellite record is 68,500 square kilometers (26,400 square miles) per year, or 7.2 percent per decade relative to the 1981 to 2010 average (Figure 3).

Antarctic sea ice

Figure 4. Antarctic sea ice extent for August 1, 2022 was 15.90 million square kilometers (6.14 million square miles). The orange line shows the 1981 to 2010 average extent for that day. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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As of this report, Antarctic sea ice extent persists at record low levels, with regional low ice extent along the Weddell Sea at its northern ice edge, much of the East Antarctic coast, and the Bellingshausen Sea. The summer has been marked by a strong Amundsen Sea Low, which tends to drive warmer air from the northwest across the Peninsula and into the northern Weddell Sea. A high pressure tendency over Queen Maud Land is also acting to bring warm air from the north across the eastern end of the Weddell Sea ice cover. Overall, conditions on the continent and adjacent seas are far warmer than is typical, with regions near the Peninsula up to 5 degrees Celsius (9 degrees Fahrenheit) above average for May through July, and temperatures in the Weddell Sea between 3 to 7 degrees Celsius (5 to 13 degrees Fahrenheit) above average. Above average temperatures extend across most of the continent and East Antarctic coast, where conditions are 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above average. Only the northern Ross Sea has significantly below average temperatures, of around 4 degrees Celsius (7 degrees Fahrenheit) below average.

A recent paper by our colleagues John Turner and others from British Antarctic Survey, along with co-authors from India and the U.S., looks at the conditions that led to the record low sea ice extent observed in February of this year. Overall, the authors attribute the low sea ice conditions to a combination of large-scale circulation patterns, including La Niña and a strong Amundsen Sea Low, and the impacts of severe regional storms moving ice away from the coast and into warmer waters and greater sunlight.

Effects of Arctic ozone depletion

Figure 5. This figure shows record low Arctic ozone concentrations observed on March 12, 2020.

Credit: NASA Goddard Earth Observing System data assimilation system (DAS).
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While the Antarctic ozone hole that develops in austral spring is well known, stratospheric ozone depletion can also occur in the Arctic, though to a lesser extent. A recent study by Marina Friedel and colleagues, based on both observations and models, finds that springtime stratospheric ozone depletion over the Arctic is consistently followed by surface temperature and precipitation anomalies consistent with a positive Arctic Oscillation, an atmospheric pattern known to have significant impacts on climate conditions over the parts of the Northern Hemisphere as well as the Arctic. The authors argue that this is because ozone depletion leads to a reduction in short-wave radiation absorption, causing persistent negative temperature anomalies in the lower stratosphere and a delayed break up of the stratospheric polar vortex. When the Arctic Oscillation is positive, sea level air pressure is lower than average over the North Pole and higher than average over the mid-latitudes. This pressure pattern helps to keep cold air in the Arctic and favors warmer temperatures over the mid-latitudes. In 2020, Arctic ozone concentrations reached a record low on March 12 of 205 Dobson Units (Figure 5) compared to an average value of 240 Dobson Units for this time of year. At the same time, the Arctic Oscillation index reached a record high positive value. As a result, central and northern Europe were exceptionally warm and dry in spring 2020, whereas wet and cold conditions prevailed in the Arctic.

Further reading

Friedel, M., G. Chiodo, A. Stenke, et al. 2022. Springtime arctic ozone depletion forces northern hemisphere climate anomalies. Nature Geoscience. doi:10.1038/s41561-022-00974-7.

Lavergne, T., S. Eastwood, Z. Teffah, H. Schyberg, and L.-A. Breivik. 2010. Sea ice motion from low resolution satellite sensors: an alternative method and its validation in the Arctic. Journal of Geophysical Research. doi:10.1029/2009JC005958.

Turner, J., C. Holmes, T. Caton Harrison, T. Phillips, B. Jena, T. Reeves-Francois, R. Fogt, E. R. Thomas, C. C. Bajish. 2022. Record low Antarctic sea ice cover in February 2022. Geophysical Research Letters. doi:10.1029/2022GL098904.

Sea ice extent near both poles was again below average, but higher than in recent years for most of the month. In the Arctic, seasonal sea ice loss began more slowly in May than in the recent years as air temperatures were closer to the 1981 to 2010 average. In the Antarctic, a slowdown in ice growth late in the month quickly brought sea ice extent levels close to record lows.

Overview of conditions

Figure 1. Arctic sea ice extent for May 2022 was 12.88 million square kilometers (4.97 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Average Arctic sea ice extent for May 2022 was 12.88 million square kilometers (4.97 million square miles) (Figure 1). This was 410,000 square kilometers (158,000 square miles) below the 1981 to 2010 average, yet it was the highest May extent since 2013. As was the case for April, sea ice extent was slow to decline, losing only 1.28 million square kilometers (494,000 square miles) during the month. Ice loss in May occurred primarily in the Bering Sea, the Barents Sea, and within Baffin Bay and Davis Strait. However, several openings, or polynyas, in the pack ice have started to form, particularly within the eastern Beaufort Sea, the Chukchi Sea, the Laptev Sea, and around Franz Joseph Land in the northern Barents Sea. Ice also started to pull back from the shores of Russia in the Kara Sea. In Hudson Bay, the ice started to melt out in the south within James Bay and off of Southampton Island in the north. Overall, the daily sea ice extent tracked within the interdecile range (encompassing 90 percent of the 1981 to 2010 daily values) for much of the month. By the end of the month, extent was close to the sea ice extent observed in late May 2012.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of June 5, 2022, along with daily ice extent data for four previous years and the record low year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for May 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2c. This plot shows average sea level pressure in the Arctic in millibars for May 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Through May, sea ice extent was tracking above levels not seen since 2013. The relatively extensive ice cover for this time of year was largely the result of lower than average temperatures in Baffin Bay. Winds from the north also slowed the retreat of ice in the Bering and Barents Seas. Within the Arctic Ocean, air temperatures at the 925 mb level (about 2,500 feet above the surface) were near average over most of the region in May, and 1 to 5 degrees Celsius (2 to 9 degrees Fahrenheit) above the 1981 to 2010 average along the coast of the Kara and East Siberian Seas, the East Greenland Sea, and the Canadian Archipelago (Figure 2b). Areas where openings formed within the ice cover were dominated by off-shore ice motion, pushing ice poleward as well as toward Fram Strait. This offshore ice motion is largely driven by a pattern of low sea level pressure over Eurasia coupled with high pressure over the Pacific sector of the Arctic (Figure 2c).

May 2022 compared to previous years

Figure 3. Monthly May ice extent for 1979 to 2022 shows a decline of 2.5 percent per decade.

Credit: National Snow and Ice Data Center
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May sea ice extent declined by 1.28 million square kilometers (494,000 square miles), or at a rate of 41,200 square kilometers (15,900 square miles) per day, which was slower than the 1981 to 2010 average. This resulted in an average May extent that ranked fourteenth lowest in the satellite record. The downward linear trend in May sea ice extent over the 44-year-satellite record is 33,700 square kilometers (13,000 square miles) per year, or 2.5 percent per decade relative to the 1981 to 2010 average (Figure 3). Based on the linear trend, since 1979, May has lost 450,000 square kilometers (174,000 square miles) of sea ice. This is equivalent to the size of the state of California.

Polynyas help kick-start seasonal ice loss

Figure 4a. This NASA Worldview image from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) on May 29, 2022 shows polynyas forming off the coast of Siberia.

Credit: NASA
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Figure 4b. This plot shows the relationship between averaged sea ice extent from July through October (in blue) and the regional average fire-favorable weather index (FFWI) over the western United States the following autumn and early winter (September to December, in red).

Credit: Zou et al., 2021
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Polynyas have begun to form, providing open water regions that strongly absorb the sun’s energy, warming the near-surface ocean mixed layer, and enhancing lateral ice melt from the sides. One of the larger polynyas is in the Laptev Sea to the west of the New Siberian Islands (Figure 4a). Despite the thin cloud cover, polynyas can be seen at the edge of the landfast ice, ice fastened to the coastline, to the west of the New Siberian Islands as well off the coast of the Taymyr Peninsula between the Kara and Laptev Seas.

A consequence of summer sea ice loss is that the ocean absorbs more of the sun’s energy. Before the ice can form again in the fall and winter, this heat has to be released back to the atmosphere. This is one of the reasons why the Arctic is warming more strongly than the global average, particularly in the fall season. Studies have suggested this amplified Arctic warming may be impacting weather systems at lower latitudes. One hypothesis is that the warm air released from the surface propagates up through the atmosphere and disrupts the polar vortex in the stratosphere. This can lead to cold air outbreaks, such as in February 2021 when cold Arctic air reached as far south as Texas, causing the failure of the power grid, billions of dollars in damage, and loss of lives. Proposed links between Arctic warming and mid-latitude weather nevertheless remain controversial and are far from settled.

Another recent study reveals a correlation between Arctic sea ice extent (averaged from July to October) and conditions favoring California wildfires after removing the long-term trend in both the sea ice and a regional fire-favorable weather conditions index. However, correlation is not causation. This study addresses the potential physical link by examining sensitivity simulations using low and high sea ice years and comparing the atmospheric conditions from climate model runs. The results suggest that during low sea ice minimum years there is tendency for low sea level air pressure over Alaska and high sea level pressure over the western United States. This results in dry and hot air flowing from the south and southwest over California, conditions favorable for wildfires there in the following autumn and early winter (Figure 4b).

Mapping volume of ice and snow over Antarctic sea ice proves difficult

Figure 5a. The graph above shows Antarctic sea ice extent as of June 5, 2022, along with daily ice extent data for four previous years and the record high year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2014 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 5b. This image shows dual frequency Ku- and Ka-band radar (KuKa) deployed over Antarctic pancake sea ice.

Credit: Povl Abrahamsen
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As reported in a previous post, this year, Antarctic sea ice shrank to the lowest extent in the satellite record at 1.92 million square kilometers (741,000 square miles) on February 25. This event was set against the background of several low minimum extents since 2014. During the month of May, sea ice tracked slightly below the 1981 to 2010 reference period, until late in the month when sea ice autumn growth slowed significantly (Figure 5a). Stronger than average winds from the north and northeast in the Belligshausen and Amundsen Sea regions led to warm conditions near the sea ice edge, inhibiting growth. At month’s end, Antarctic sea ice extent was above only 1980, 1986, 2017, and 2019 in the 44-year record. Sea ice is particularly low in the Amundsen and Weddell Seas.

Reliable information on Antarctic sea ice thickness, important for gaining a fuller understanding of the Antarctic sea ice system, remains elusive. In the Arctic, sea ice thickness can be more accurately estimated using satellite altimeters. However, studies suggest that satellite altimeters may be over-estimating ice thickness compared to ship-based observations. This may be because of the way snow cover on the ice affects the measurements. There are still large uncertainties in the Antarctic snow and sea ice thickness, and hence the overall sea ice volume.

A United Kingdom-led project, called Drivers and Effects of Fluctuations in sea Ice in the ANTarctic (DEFIANT), aims to address this problem. The DEFIANT team is particularly interested in learning how radar waves interact with the snow that covers Antarctic sea ice. A recent DEFIANT field campaign involved three scientists travelling to the Weddell Sea with a radar designed to mimic those mounted on satellites. They investigated radar penetration into snow of different ages, densities, and surface roughness (Figure 5b). The results will help the research community better understand how to measure the underlying sea ice thickness using satellites. In 2023, two DEFIANT-affiliated scientists will spend the entire winter in Antarctica with the same radar instrument, monitoring the snow cover and its radar-reflective properties.

References

Zou, Y., P. J. Rasch, H. Wang, et al. 2021. Increasing large wildfires over the western United States linked to diminishing sea ice in the Arctic. Nature Communications. doi:10.1038/s41467-021-26232-9

Arctic spring melt has begun. Ice extent declined most substantially in the Bering Sea and the Sea of Okhotsk. Overall decline was slower than average through the month.

Overview of conditions

Figure 1. Arctic sea ice extent for April 2022 was 14.06 million square kilometers (5.43 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Average Arctic sea ice extent for April 2022 was 14.06 million square kilometers (5.43 million square miles) (Figure 1). This was 630,000 square kilometers (243,000 square miles) below the 1981 to 2010 average and ranked eleventh lowest in the 44-year satellite record. Extent declined slowly through the beginning of the month, with only 87,000 square kilometers (33,600 square miles) of ice loss between April 1 and April 10. The decline then proceeded at an average pace for this time of year through the reminder of the month. Reductions in sea ice extent during April occurred primarily in the Bering Sea and the Sea of Okhotsk. Other regions had small losses at most. The southern Barents Sea lost some ice, but the channel of open water north of Novaya Zemlya that persisted for much of the winter closed during April. Overall, the daily sea ice extent tracked just below the interdecile range (below 90 percent of past daily values) for the month.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of May 2, 2022, along with daily ice extent data for four previous years and the record low year. 2022 is shown in blue, 2021 in green, 2020 in orange, 2019 in brown, 2018 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for April 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2c. This plot shows average sea level pressure in the Arctic in millibars for April 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
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Figure 2d. This animation (click to see animation) shows the polynyas, or openings in the ice cover, that formed in the Chukchi Sea from April 12 to 30, 2022. In April, strong offshore winds over the northwest coast of Alaska led to the formation of these polynyas. 

Credit: Agnieszka Gautier, National Snow and Ice Data Center
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During April, temperatures at the 925 mb level (about 2,500 feet above the surface) over the Arctic Ocean were above average. Most areas were 2 to 3 degrees Celsius (4 to 5 degrees Fahrenheit) above average, but in the Beaufort Sea, April temperatures were up to 5 to 6 degrees Celsius (9 to 11 degrees Fahrenheit) above average (Figure 2b). This was accompanied by a strong Beaufort High pressure cell through the month (Figure 2c).

Strong offshore winds over the northwest coast of Alaska led to openings in the ice cover, called polynyas. The first pulse of winds began on March 21. At that time, surface air temperatures were still well below freezing, and the water in the coastal polynya quickly refroze. By April 9, the offshore push of the ice ceased and the polynya iced over completely. However, starting on April 12, a second round of offshore wind pushed the ice away from the coast, initiating another polynya. Refreezing began anew in the open water areas, but the ice growth was noticeably slower, reflecting the higher surface air temperatures by the end of the month (Figure 2d).

April 2022 compared to previous years

Figure 3. Monthly April ice extent for 1979 to 2022 shows a decline of 2.6 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend in April sea ice extent over the 44-year-satellite record is 37,900 square kilometers (14,600 square miles) per year, or 2.6 percent per decade relative to the 1981 to 2010 average (Figure 3). Based on the linear trend, since 1979, April has lost 1.68 million square kilometers (649,000 square miles) of sea ice. This is equivalent to the size of the state of Alaska.

Sea ice age

Figure 4. This map shows the age of Arctic sea ice for the March 12 to 18 period in (a) 1985 and (b) 2022. The oldest ice, greater than 4 years old, is in red. Plot (c) shows the timeseries from 1985 through 2022 of percent cover of the Arctic Ocean domain (inset, purple region) by different sea ice ages during the March 12 to 18 period.

Credit: M. Tschudi, W. Meier, and Stewart, NASA NSIDC DAAC
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With the onset of spring, it is time again for a check-in on sea ice age—the number of years that a parcel of ice has survived summer melt. As noted in previous posts, ice age provides a qualitative assessment of thickness, as older ice has more chances to thicken through ridging, rafting, and bottom ice growth (accretion) during winter. The coverage of the old, thick ice has a significant control on how much total ice survives the summer melt season—the first-year ice that grows thermodynamically over winter is more easily melted away during summer. That which survives through the summer melt season grows in age by one year. The extent of old ice declines through the winter when it drifts out of the Arctic through the Fram or Nares Strait. At the end of last summer, the extent of the oldest ice (greater than 4 years old) tied with 2012 for the lowest in the satellite record. This spring, we continue to see a dominance of first-year ice (Figure 4). The percentage of the greater than 4-year-old ice, which once comprised over 30 percent of the Arctic Ocean, now makes up only 3.1 percent of the ice cover.

Bering Sea crabs

Figure 5. The fishing boat Pinnacle travels through a Bering Sea ice floe on January 25, 2022. Crab fishing is dangerous work due to frequently rough seas, icing, and dense pack ice.

Credit: Loren Holmes/Anchorage Daily News.
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The Bering Sea is an important crab fishery, with several species represented. Crab fishing is dangerous work because of frequently rough seas, icing on the ship’s superstructure, and dense pack ice (Figure 5). This past winter, the population of lucrative snow crabs was down substantially. This decline in crabs appears to be related to low sea ice extent during the 2018 and 2019 winters. Snow crabs prefer cold bottom water that protects the young from predators. The cold-water pool on the Bering Sea floor is caused by winter ice formation where dense, cold, and salty water sinks as the ice grows. However, in 2018 and 2019 there was very little ice. This opened young crabs to more predation, and far fewer survived to maturity.

Antarctica rising

Figure 6. Antarctic sea ice extent for April 2022 was 5.84 million square kilometers (2.25 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

After the record low minimum Antarctic sea ice extent at the end of February and the strong heat wave that followed in mid-March, conditions in the Southern Ocean have calmed down. Ice extent remains low for this time of year below the interdecile range, but is above 2017, 2018, and 2019, as well as 1980. Extent remained below average in the Weddell, eastern Ross, and western Amundsen-Bellingshausen regions, but near average around the rest of the continent (Figure 6). Through April, ice extent increases in all regions around the continent, but with relatively slower growth in the Amundsen-Bellingshausen Seas.

First Multidisciplinary Drifting Observatory for the Study of Arctic Climate science team meeting

Figure 7. The first in-person Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) science conference was held at the end of April in Potsdam, Germany. This was the first chance to present findings from the year-long expedition and pave the way for future analysis and collaboration.

Credit: Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) Expedition
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The Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition took place during 2019 and 2020 when the German icebreaker, Polarstern, was frozen into the ice and drifted across the Arctic for nearly a year. During the year, numerous observations were taken of the atmosphere, ocean, sea ice, and biogeochemistry. The scientific analysis is ongoing, and exciting results are starting to be reported.

The first in-person MOSAiC science conference was held at the end of April in Potsdam, Germany (Figure 7). This was the first chance to present findings from the year-long expedition and pave the way for future analysis and collaboration. Science teams from each discipline (atmosphere, ocean, sea ice, snow, remote sensing, ecosystem, biogeochemistry) discussed initial research results. Key to the success of MOSAiC is the strong interdisciplinary collaboration of the projects needed to provide a holistic understanding of Arctic Ocean changes and their impacts. NSIDC scientist Julienne Stroeve presented on the impacts of a rain-on-snow event in mid-September and the potential impact this would have on satellite retrievals of sea ice concentration, snow depth, and ice thickness. In January 2023, all MOSAiC data collected will be made available to the wider science community.

David Barber

Figure 8. Polar scientist David Barber of the University of Manitoba passed away on April 15, 2022.

Credit: University of Manitoba
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It is with sadness that we note the passing of one of the world’s pre-eminent polar scientists, David Barber, of the University of Manitoba, who died on April 15, 2022. He was a force in Canadian science, leading several large projects that increased understanding of sea ice and the Arctic.

References

Bernton, H., and L. Holmes. 2022. A crab boat’s quest for snow crab in a Bering Sea upended by climate change. The Seattle Times. https://pulitzercenter.org/stories/crab-boats-quest-snow-crab-bering-sea-upended-climate-change

Rascoe, A. 2022. Snow crabs in the Bering Sea have been hard to find — partially due to climate change. National Public Radio. https://www.npr.org/2022/04/10/1091927681/snow-crabs-in-the-bering-sea-have-been-hard-to-find-partially-due-to-climate-cha.

Thoman, Jr., R. L., U .S. Bhatt, P. A. Bieniek, B. R. Brettschneider, M. Brubaker, S. L. Danielson, Z. Labe, R. Lader, W. N. Meier, G. Sheffield, and J. E. Walsh. 2020. The record low Bering Sea ice extent in 2018: Context, impacts, and an assessment of the role of anthropogenic climate change. Bulletin of the American Meteorological Society. doi:10.1175/BAMS-D-19-0175.1.

University of Manitoba. 2022. Mourning the loss of visionary Arctic researcher, Dr. David Barber. UM Today News. https://news.umanitoba.ca/mourning-the-loss-of-visionary-arctic-researcher-dr-david-barber/.

Sea ice age data sets from the NSIDC DAAC: Quicklook Arctic Weekly EASE-Grid Sea Ice Age, Version 1 and EASE-Grid Sea Ice Age, Version 4.

Arctic sea ice is approaching its seasonal peak, with below-average sea ice extent in the Barents Sea and the Sea of Okhotsk, but near-average ice extent elsewhere. Antarctic sea ice extent set a record low minimum for the satellite data era. However, two regions of high interest to researchers remained locked in ice: Thwaites Glacier and the central Weddell Sea.

Overview of conditions

Figure 1a. Arctic sea ice extent for February 2022 was 14.61 million square kilometers (5.64 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Figure 1b. The graph above shows Arctic sea ice extent as of March 7, 2022, along with daily ice extent data for four previous years and the record low year. 2021 to 2022 is shown in blue, 2020 to 2021 in green, 2019 to 2020 in orange, 2018 to 2019 in brown, 2017 to 2018 in magenta, and 2012 to 2013 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

Average Arctic sea ice extent for February 2022 was 14.61 million square kilometers (5.64 million square miles), ranking fourteenth lowest in the satellite record. The 2022 extent was 690,000 square kilometers (266,000 square miles) below the 1981 to 2010 average. Through most of February, extent hovered near the interdecile range, roughly at the lowest 10 percent of the measured extents for those days. Regionally, the sea ice extent was near average in the Bering Sea but continued to be well below average in the Sea of Okhotsk. In the Barents Sea, extent was below average, and a narrow open-water area extended north of Novaya Zemlya. Extent also remained below average in the Gulf of St. Lawrence and along the eastern Greenland coast. As is generally the case near the maximum sea ice extent, there are ups and downs in extent associated with storms moving the ice around, melt along the southern ice margins, and subsequent regrowth.

Conditions in context

Figure 2a. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for February 2022. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

Figure 2b. This plot shows average sea level pressure in the Arctic in millibars for February 2022. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

In February 2022, temperatures at the 925 hPa level (about 2,500 feet above sea level) ranged from 1 to over 8 degrees Celsius (2 to 14 degrees Fahrenheit) above the 1981 to 2010 average along the Eurasian coast and across the central Arctic Ocean (Figure 2a). However, cool conditions prevailed over much of Canada and Baffin Bay; temperatures were generally 2 to 7 degrees Celsius (4 to 13 degrees Fahrenheit) below average. The sea level air pressure pattern in February was marked by strong low pressure centered over the North Atlantic and high pressure over central Asia, acting to drive air northward from Eastern Europe to the central Arctic, consistent with the above average temperatures there (Figure 2b). In North America, low pressure over the North Atlantic, extending over Baffin Bay, drew Arctic air southward over eastern Canada, bringing cool conditions to the area.

February 2022 compared to previous years

Figure 3. Monthly February ice extent for 1979 to 2022 shows a decline of 2.8 percent per decade.

Credit: National Snow and Ice Data Center
High-resolution image

The downward linear trend in February sea ice extent over the 44-year satellite record is 42,500 square kilometers (16,400 square miles) per year, or 2.8 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, February has seen a loss of 1.82 million square kilometers (703,000 square miles). This is equivalent to about seven times the area of Oregon.

Antarctic sea ice minimum sets a record

Figure 4a. Before 2022, the previous record low Antarctic sea ice extent was observed on March 3, 2017. This figure shows the difference in sea ice extent from that date (shown in white) compared with the new record low on February 25, 2022 (shown in dark blue). Ice present on both dates is shown in light blue.

Credit: National Snow and Ice Data Center
High-resolution image

Figure 4b. This figure shows the pattern of the 2021 to 2022 Antarctic sea ice decline since the September winter maximum. Each panel shows the sea ice extent for the two dates in the legend, with the earlier date extent in white and the later date extent in light blue.

Credit: National Snow and Ice Data Center
High-resolution image

In the south, Antarctic sea ice recently reached its late-summer minimum, dropping below all previous minimum ice extents in the satellite record (Figure 4a). For the first time since the satellite record began in 1979, extent fell below 2 million square kilometers (772,000 square miles), reaching a minimum extent of 1.92 million square kilometers (741,000 square miles) on February 25. Ice extent declined at a near-average rate through most of the month at about 40,000 square kilometers (15,400 square miles) per day, but the decline significantly slowed to about 15,000 square kilometers (5,800 square miles) per day towards the end of the month.

Following the unusually early and above average sea ice maximum extent on September 1, there was a rapid decline in ice extent through the austral spring and summer, with the most notable feature being the clearing out of ice from the Ross and Amundsen Sea sectors during January and February as well as the loss of ice from the northwestern Weddell Sea region during that period (Figure 4b). Much of the Antarctic coast is still ice-free and sea ice remains well below average in the eastern Ross Sea, western Bellingshausen Sea, and northwestern Weddell Sea. However, persistent patches of high concentration sea ice in the area of Pine Island Bay and in the central Weddell Sea are obstructing research groups trying to work in those areas. The RV Nathaniel B Palmer, operated by the National Science Foundation (NSF), and the RV Araon, operated by South Korea’s Korean Polar Research Institute (KOPRI), have been attempting to conduct research near the outlet of Thwaites Glacier. The research teams were forced to work at an adjacent region to the west, the Dotson Ice Shelf, to avoid the heavy ice conditions near Thwaites.

Ups and downs in the southern ice

Figure 5a. This plot shows the annual Antarctic minimum daily (5-day running average) extent for 1979 to 2022 (black) and the 1979 to 2022 trend line (blue). For the first time since the satellite record began in 1979, sea ice in the Southern Hemisphere fell below 2 million square kilometers (772,000 square miles), reaching a minimum of 1.92 million square kilometers (741,000 square miles) on February 25.

Credit: National Snow and Ice Data Center
High-resolution image

Figure 5b. This plot shows the changes in the trend of seasonal sea ice minimums over the satellite record for Antarctic sea ice, beginning with the trend after ten years and proceeding year-by-year. For much of the satellite monitoring period, the trend has been towards increasing ice, but the vertical bars show that the high variability in the records means that the trend is not statistically significant. As of 2022, the net trend is very close to zero.

Credit: National Snow and Ice Data Center
High-resolution image

The Antarctic sea ice is notable for its variability, both seasonally, losing over 80 percent of its ice cover from its maximum to its annual minimum extent, and from year to year. While 2022 had a record low minimum, the highest minimum in the satellite record was observed as recently as 2015 (Figure 5a). The effect of this large year to year variability on computed trends is evident when plotting how the trend has changed over time (Figure 5b). We calculated the trend for the period of 1979 to 1988, then 1979 to 1989, then 1979 to 1990, and so forth.

The trend is initially positive for the 1979 to 1988 period, but then dips negative for a couple years, then bounces between positive and negative until the year 2001, after which it remained positive through 2021. Also plotted is the 2 standard deviation range of the trend as the vertical “whiskers” for each year; this is a measure of how confident one should be in the trend values. If the 2 standard deviation range for a computed trend crosses the zero line (i.e., encompasses both positive and negative values), it means that the trend value may simply be due to the year-to-year swings in the extent. Phrased differently, it means that the trend does not meet the 95 percent confidence level for statistical significance. So while the trend in minimum extent has been largely positive over the past two decades, it has not been significant except the three-year period, 2014 to 2016. Through 2022, the trend starting in 1979 is ever so slightly negative again: -18 square kilometers (-6.94 square miles) per year. But it is still not a significant trend. Variability in summer continues to rule Antarctic sea ice extent.

Eos recently published an article that summarizes three different modeling studies that attempt to explain the causes of the variability and the (until this year) positive trend in Antarctic sea ice extent. The article finds that while winds and sea surface temperature are important contributors to the growth of Antarctic sea ice over the last 30+ years, there are likely additional factors at play.

Search for the Endurance

Figure 6a. Mrs. Chippy, the resident cat of Endurance, the vessel that carried Ernest Shackleton and his team to Antarctica in 1914, stands on the shoulder of a crewmember. Mrs. Chippy did not survive the expedition.

Credit: Perce Blackborow
High-resolution image

Figure 6b. These images show the stern of the Endurance, the ship used by Ernest Shackleton to reach the Weddell Sea on his ill-fated Imperial Trans-Antarctic Expedition. The ship was found in 3,000 meters (10,000 feet) of water in the northwestern Weddell Sea by a search expedition using uncrewed submersible vehicles.

Credit: Falklands Maritime Heritage Trust and National Geographic.
High-resolution image

In the Weddell Sea, the South African research icebreaker RV Agulhas II has been attempting to find the wreck of the Endurance on the seafloor. The Endurance is the vessel that brought Ernest Shackleton and his team to Antarctica in 1914, only to be blocked by sea ice. The ice later crushed the ship and the team was forced to trek across the sea ice and sail to a small, uninhabited island near the tip of the Antarctic Peninsula. Shackleton and five others then sailed in a lifeboat over 1,600 kilometers (1,000 miles) to South Georgia Island, one of the greatest polar voyages in history, to reach civilization. They then returned in a Chilean ship, the Yelcho, to rescue the rest of the expeditioners on Elephant Island. Miraculously, all of the human crew were successfully rescued. However, several sled dogs and one male cat, Mrs. Chippy, did not survive (Figure 6a).

On March 5, the Endurance was found by undersea drones operating from the South African ice breaker (Figure 6b). This was after just two weeks of searching in the area where the navigator of the 1915 expedition, Frank Worsely, noted its last location. It was found in 3,000 meters (10,000 feet) of water in near-pristine condition because of the absence of wood-boring worms in the Weddell benthic ecosystem. The ship was found just 6 kilometers (4 miles) from the last reported location, made on November 21, 1915, with sextant and chronometer.

Further reading

Alexander, C., and J. Dorman. 2003. The Endurance: Shackleton’s Legendary Antarctic Expedition. Columbia TriStar.

Amos, J. 2022. Endurance: Shackleton’s lost ship is found in Antarctic. BBC. https://www.bbc.com/news/science-environment-60662541

Blanchard-Wrigglesworth, E., I. Eisenman, S. Zhang, S. Sun, and A. Donohoe. 2022. New Perspectives on the Enigma of Expanding Antarctic Sea Ice. Eos.
https://eos.org/science-updates/new-perspectives-on-the-enigma-of-expanding-antarctic-sea-ice

Davidson, L. 2022. The Adventures of Mrs. Chippy, Shackleton’s Seafaring Cat. History Hit. https://www.historyhit.com/mrs-chippy-shackletons-seafaring-cat/

Sir Ernest Shackleton Endurance Expedition Trans-Antarctica 1914-1917 – 1, Departure. Cool Antarctica. https://www.coolantarctica.com/Antarctica%20fact%20file/History/Shackleton-Endurance-Trans-Antarctic_expedition.php

Worsley, F. A. 1998. Shackleton’s boat journey. WW Norton & Company.

Update

When we first published this post, the Endurance had not yet been found. We updated this post on March 9, 2022, to include the information about the discovery of the Endurance. 

By early January 2022, Arctic sea ice extent, while well below average, was within the lowest decile of recorded extents of the 1981 to 2010 reference period. Sea ice now completely covers Hudson Bay; the only area with substantially below average extent is in southern Baffin Bay and north of Labrador.

Overview of conditions

Figure 1. Arctic sea ice extent for December 2021 was 12.19 million square kilometers (4.71 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Average Arctic sea ice extent for December 2021 was 12.19 million square kilometers (4.71 million square miles), which ranked thirteenth lowest in the satellite record. The 2021 extent was 650,000 square kilometers (251,000 square miles) below the 1981 to 2010 average. As of early January 2022, sea ice completely covers Hudson Bay. The only area with extent remarkably below normal is southern Baffin Bay and off the coast of Labrador, where the December sea ice extent ranked fourth lowest.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of January 4, 2022, along with daily ice extent data for four previous years and the record low year. 2021 to 2022 is shown in blue, 2020 to 2021 in green, 2019 to 2020 in orange, 2018 to 2019 in brown, 2017 to 2018 in magenta, and 2012 to 2013 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for December 2021. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars for December 2021. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

The air temperature pattern averaged for December 2021 at the 925 millibar level (about 2,500 feet above the surface) was characterized by above average temperatures. Temperatures were up to 6 degrees Celsius (11 degrees Fahrenheit) above average over Greenland, north of the Canadian Arctic Archipelago, and the East Greenland Sea. Three areas of below average temperatures were found over western and eastern Eurasia and northwestern Canada (Figure 2b). The corresponding sea level pressure pattern for December 2021 featured fairly low pressures (less than 1,015 millibars) encompassing essentially all of the Arctic except for the Laptev Sea region (Figure 2c). These pressures were nevertheless not substantially unusual compared to average—at most 6 to 7 millibars below average. The notable exception is south of the Aleutian Islands, where the sea level pressure was up to 24 millibars above average.

December 2021 compared to previous years

Figure 3. Monthly December ice extent for 1979 to 2021 shows a decline of 3.5 percent per decade.

Credit: National Snow and Ice Data Center
High-resolution image

The downward linear trend in December sea ice extent over the 43-year satellite record is 45,000 square kilometers (17,400 square miles) per year, or 3.5 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, December has seen a loss of 1.88 million square kilometers (726,000 square miles). This is equivalent to about three times the size of Texas.

Hudson Bay ices over

Figure 4. This NASA Worldview image shows the last part of  Hudson Bay freezing up along the southeast coast as of December 23, 2021. After a late freeze up, Hudson Bay is completely ice covered as of early January 2022.

Credit: NASA
High-resolution image

In our previous post, we noted that by the end of November, the northern half of Hudson Bay is usually completely iced over. As of the end of November 2021, only the far north was frozen over; the rest of the bay was ice free except for a narrow band of ice along the western coastline. However, as lower temperatures kicked in and the upper ocean lost the heat that it had gained in summer, the entire bay subsequently froze over. The ice cover is now complete.

Antarctic notes

Figure 5. Antarctic sea ice extent for December 2021 was 9.2 million square kilometers (3.55 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

Antarctic sea ice extent for December 2021 was low overall, tracking at similar extents seen in 2017. Regionally, extent was particularly low in the Weddell Sea and southern Ross Sea regions. Several large polynyas formed in the eastern Weddell Sea; the Maud Rise Polynya opened in late November and then spread east to northeast. This is unusual; normally, the polynya extends south and west of its initiation point. The Southern Annular Mode (SAM) was in a strong positive phase through the first half of the month, indicating strong westerly winds and a strong low-pressure area in the Amundsen Sea. Sea ice conditions are not yet favorable for two planned cruises near Thwaites Glacier, one by the US Antarctic research program (RV Nathaniel B. Palmer) and the other by the South Korean (RV Araon). Ships are due to arrive in late January.

Killer whales in the Arctic

Bowhead whales have played an integral role in the cultural and subsistence life of Inuit communities for millennia. New research at the University of Washington analyzing acoustic data has found that the loss of sea ice has allowed killer whales, also known as Orcas, to venture into waters that were once inaccessible to them. The expanding range of killer whales, a top predator, has potential ramification for the Arctic food web and especially bowhead whales. Indigenous Arctic communities have noted an increased number of carcasses of bowhead whales in the Chukchi and Beaufort seas that were preyed upon by Orcas. Normally, bowheads can avoid predation by retreating into protective areas of heavy sea ice that the smaller Orcas cannot break through to breathe. If the bowheads must spend more time in thick ice, this can be a problem because feeding opportunities are more limited. Calves that cannot break through the ice may also drown.

The sea ice extent has been quickly growing, and by the end of October, ice covered most of the Arctic Ocean. Overall, the ice extent remained below average for this time of year in the Barents and Kara Seas, as well as within northern Baffin Bay and the East Greenland Sea.

Overview of conditions

Figure 1. Arctic sea ice extent for October 2021 was 6.77 million square kilometers (2.61 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
High-resolution image

The monthly average extent for October 2021 was 6.77 million square kilometers (2.61 million square miles). This ranked eighth lowest in the long-term satellite data record, tied with 2017. It was 1.44 million square kilometers (556,000 square miles) greater than the record low of 5.33 million square kilometers (2.06 million square miles) recorded in 2020, and 1.58 million square kilometers (610,000 square miles) below the 1981 to 2010 long-term average. Ice growth was robust across the Eurasian side of the Arctic, including the East Greenland Sea, but there was little expansion of ice southwards within the eastern Beaufort Sea.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of November 1, 2021, along with daily ice extent data for four previous years and the record low year. 2021 is shown in blue, 2020 in green, 2019 in orange, 2018 in brown, 2017 in magenta, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for October 2021. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

Figure 2c. This plot shows the departure from average sea level pressure in the Arctic at the 925 hPa level, in degrees Celsius, for October 2021. Yellows and reds indicate higher than average air pressures; blues and purples indicate lower than average air pressures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Laboratory
High-resolution image

As of October 31, sea ice extent is tracking higher than any year since 2015, as well as higher than observed in 2007, 2011, and 2012 (Figure 2a).

Average monthly air temperatures were well below freezing across much of the Arctic Ocean in October, the exceptions being along the coastal regions of the Barents Sea and across the North Atlantic region. Nevertheless, air temperatures at the 925 hPa level (about 2,500 feet above the surface) were above the 1981 to 2010 average, up to 8 degrees Celsius (14 degrees Fahrenheit) above average north of Greenland and the Canadian Archipelago (Figure 2b).

Above average temperatures were related in part to unusually low sea level pressure extending from Siberia across to Alaska, coupled with above average sea level pressure northeast of Greenland extending down towards Baffin Bay. In particular, the strong sea level pressure gradient between the low and high sea level pressure near the Canadian Arctic Archipelago helped to funnel winds from the south over Baffin Bay, which is still ice-free, northwards towards the central Arctic Ocean (Figure 2c).

Overall, ice extent increased by 99,700 square kilometers (38,500 square miles) per day during the month of October. This rate of increase was larger than the 1981 to 2010 average of 89,200 square kilometers (34,400 square miles) per day.

October 2021 compared to previous years

Figure 3. Monthly October ice extent for 1979 to 2021 shows a decline of 9.8 percent per decade.

Credit: National Snow and Ice Data Center
High-resolution image

The downward linear trend in October sea ice extent over the satellite record is 82,100 square kilometers (31,700 square miles) per year, or 9.8 percent per decade relative to the 1981 to 2010 average (Figure 3). While percentagewise, the overall long-term trend is largest in September, the actual amount (based on the linear trend) of ice lost per year is larger in October: 82,100 square kilometers (31,700 square miles) versus 81,200 square kilometers (31,400 square miles) in September.

Overall, since 1979, October has lost 3.45 million square kilometers (1.33 million square miles) of ice, based on the linear trend. This is equivalent to twice the size of the state of Alaska.

Last ice refuge continues to show signs of weakness

Figure 4. This NASA Moderate Resolution Imaging Spectroradiometer (MODIS) image from May 20, 2020, shows a large polynya, or open water region, that formed north of Ellesmere Island in Canada.

Credit: NASA
High-resolution image

In February 2018, a large polynya (open water region) formed northeast of Greenland. In May 2020, another large polynya formed north of Ellesmere Island (Figure 4). This region contains the oldest and thickest ice in the Arctic Ocean, a result of the Beaufort Gyre circulation, which pushes the ice towards the coasts of Greenland and the Canadian Archipelago, where it compresses along the coasts. However, during the polynya formation events, winds helped to push the ice away from the shores, leaving open water for several days. While such events have occurred before, they are rare. However, as the ice cover continues to thin, the ice will become more vulnerable to disruption by winds that can form such polynyas and seaward ridging and rafting of the ice.

Seeing daylight in the Antarctic

Figure 5. The graph above shows Antarctic sea ice extent as of November 1, 2021, along with daily ice extent data for four previous years and the record low year. 2021 is shown in blue, 2020 in green, 2019 in orange, 2018 in brown, 2017 in magenta, and 2014 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
High-resolution image

Since the Antarctic maximum sea ice extent was reached on September 1, 2021, ice extent has been in a steep decline. Extent went from being above the interdecile (ninetieth percentile) range to being below the tenth percentile for most of October. As a result, sea ice extent in the Antarctic is currently tracking as the third lowest, behind only 2016 and 1986. Sea ice extent is particularly low along the western side of the Antarctic Peninsula, including the northern Weddell Sea and the central Indian Ocean sector. Air temperatures at the 925 hPa level (about 2,500 feet above the surface) were up to 6 degrees Celsius (11 degrees Fahrenheit) above average within the Weddell Sea. A strong low pressure feature in the Amundsen Sea and above average air pressure in the area south of Australia drove winds that led to the pattern of sea ice extent around the continent.

References

Moore, G. W. K., S. E. L. Howell, and M. Brady. 2021. First observations of a transient polynya in the Last Ice Area north of Ellesmere Island. Geophysical Research Letters. doi: 10.1029/2021GL095099