While large parts of the world saw record breaking heat in July, and Antarctic sea ice extent remained at record daily lows as assessed over the satellite record, Arctic sea ice extent for July was only the twelfth lowest in the satellite record. At month’s end, ice concentrations were low north of the Laptev Sea; however, the Northern Sea Route and the Northwest Passage retained considerable ice.

Overview of conditions

Figure 1a. Arctic sea ice extent for July 2023 was 8.18 million square kilometers (3.16 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. This map shows a large opening on August 1, 2023, in the Laptev and East Siberian Seas and extensive open water north of Alaska and the Mackenzie River Delta. Sea ice concentration data are from Advanced Microwave Scanning Radiometer 2 (AMSR2) imagery.

Credit: University of Bremen
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For the month of July, Arctic sea ice extent declined at a pace of 93,300 square kilometers (36,000 square miles) per day, near the 1981 to 2010 average of 86,900 square kilometers (33,600 square miles) per day (Figure 1a). The July average Arctic sea ice extent of 8.18 million square kilometers (3.16 million square miles) was the twelfth lowest in the satellite record, and 1.29 million square kilometers (498,000 square miles) below the 1981 to 2010 reference period. By stark contrast, Antarctic sea ice extent remained far below previous record daily lows throughout the month. While there is speculation that a fundamental change in the Antarctic sea ice system is afoot, there is some evidence from early satellite data that extent may have been similarly low in 1966.

The sea ice concentration image on August 1, 2023, from the Advanced Microwave Scanning Radiometer 2 (AMSR2) offers a detailed view of Arctic sea ice conditions (Figure1b). Large parts of the Laptev and East Siberian seas are largely ice free, and a large area of fairly low ice concentration extends north of the Laptev Sea. However, ice is still present along much of the Northern Sea Route, noting of course that Russian ice breakers are quite capable of keeping routes open. The ice edge has retreated to well north of the Alaskan and Mackenzie Delta coasts, but it is clear that the southern (Amundsen’s) route through the Northwest Passage is still choked with ice. To date since July 1, 2.86 million square kilometers (1.10 million square miles) of sea ice have melted.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of August 1 2023, along with daily ice extent data for four previous years and the record low year. 2023 is shown in blue, 2022 in green, 2021 in orange, 2020 in brown, 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
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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 July 1 to 29, 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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Figure 2c. This plot shows average sea level pressure in the Arctic in millibars from July 1 to 29, 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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Air temperatures at the 925 hPa level (approximately 2,500 feet above the surface) averaged for July 2023 were with one exception unremarkable (Figure 2). This contrasts sharply with the record high global average surface air temperature (2 meters or 6.6 feet above the surface) for the month as shown in records compiled by NASA, the National Oceanic and Atmospheric Administration (NOAA) and other agencies. Arctic temperatures at the 925 hPa level were from 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above average across much of the Arctic Ocean but below average by 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) over the Laptev Sea, which as noted above is largely ice free. The one area of pronounced warmth is centered over the Mackenzie River Delta, with temperatures up to 7 degrees Celsius (13 degrees Fahrenheit) above average. The atmospheric circulation pattern for the month was by contrast quite interesting, with low pressure over the Eurasian side of the Arctic and high pressure over the North American side (Figure 2c). As a result, there was a strong pressure gradient across the central Arctic Ocean extending to the east of Svalbard and then towards Iceland, pointing to strong winds and hence strong sea ice transport.

July 2023 compared to previous years

Figure 3. Monthly July ice extent for 1979 to 2023 shows a decline of 7.0 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend for Arctic sea ice extent in July over the 45-year satellite record is 66,500 square kilometers (25,700 square miles) per year, or 7.0 percent per decade relative to the 1981 to 2010 average (Figure 3). Based on the linear trend, since 1979, July has lost 2.92 million square kilometers (1.13 million square miles) of ice. This is roughly equivalent to four times the size of Texas.

An update on the Southern Hemisphere

Figure 4a. Antarctic sea ice extent for July 2023 was 13.49 million square kilometers (5.21 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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Figure 4b. The graph above shows Antarctic sea ice extent as of August 1, 2023, along with daily ice extent data for four previous years and the record high year. 2023 is shown in blue, 2022 in green, 2021 in orange, 2020 in brown, 2019 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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While Arctic sea ice is in the midst of the melt season, Antarctic sea ice is growing, but only slowly for this time of year. Antarctic sea ice extent averaged for July was at a record low at 13.49 million square kilometers (5.21 million square miles), and 1.50 million square kilometers (579,000 square miles) below the previous satellite record low set in 2022 (Figure 4a and 4b). As discussed in the previous post, there is speculation that the Antarctic sea ice system has entered a new regime, in which ocean heat is now playing a stronger role in limiting autumn and winter ice growth and enhancing spring and summer melt.

While this very low extent has garnered much attention, as well as consternation, a study led by colleague Dave Gallaher several years ago provides evidence from early Nimbus satellite data that sea ice extent in the winter of 1966 may have rivaled the very low level seen today. There are caveats. First, the Nimbus data for 1966 is for August, not September, the month with the annual highest average extent in the Antarctic. Second, there is substantial uncertainty in the 1966 extent because of the limited data from the low resolution visible-band Nimbus images (notably cloud cover) and challenges in interpreting the imagery. The estimated August 1966 sea ice extent from Nimbus is 15.90 million square kilometers (6.14 million square miles). A simple projection, based on data through July 1, yields an August 2023 extent of August 15.07 million square kilometers (5.82 million square miles), still significantly lower than the 1966 data suggest. Despite these uncertainties, the Nimbus data is consistent with observations from the satellite passive microwave record that Antarctic sea ice extent is highly variable.

A second information source, from a reconstruction of Antarctic sea ice led by Ryan Fogt, a professor at Ohio University, suggests that the present level is well below anything seen since the earliest Southern Ocean weather observations, back to 1905. Fogt and colleagues first established how weather station data are correlated with observed sea ice extent from 1979 through 2020. Using this information together with weather station records that go back to the early 1900s, they deduce what sea ice extent was likely to have been between 1905 and 2020, along with what its variability was likely to have been.

Further reading

Fogt, R. L., A. M. Sleinkofer, M. N. Raphael, H. S. and Handcock. 2022a. A regime shift in seasonal total Antarctic sea ice extent in the twentieth century. Nature Climate Change 12, 54– 62. doi:10.1038/s41558-021-01254-9.

Gallaher, D. W., G. G. Campbell, W. N. and Meier. 2013. Anomalous variability in Antarctic sea ice extents during the 1960s with the use of Nimbus data. IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing, 7(3), 881-887. doi:10.1109/JSTARS.2013.2264391.

Sunlight has returned to the highest latitudes in the Arctic, while in the Antarctic autumn is settling in. The seasonal decline of Arctic sea ice extent since the March 6 annual maximum has been slow, but daily extent has remained among the third to sixth lowest in the satellite record. Since the seasonal minimum reached on February 21, Antarctic sea ice has expanded at a fairly typical pace.

Overview of conditions

Figure 1. Arctic sea ice extent for March 2023 was 14.44 million square kilometers (5.58 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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Figure 1b. The graph above shows Arctic sea ice extent as of April 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 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
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The March 2023 average Arctic sea ice extent was 14.44 million square kilometers (5.58 million square miles), the sixth lowest March in the satellite record (Figure 1a). March monthly average extent was 990,000 square kilometers (382,000 square miles) below the 1981 to 2010 average of 15.43 million square kilometers (5.96 million square miles), but 150,000 square kilometers (57,900 square miles) above the record low set in March 2017 (Figure 1b).

After the March 6 seasonal maximum, extent declined for a week, but then remained almost constant during the second half of the month. Ice extent was slightly below average in almost all areas, but particularly in the Sea of Okhotsk and in the Gulf of St. Lawrence, with smaller retreats in the Barents and Bering Seas. Sea ice concentration within the ice pack was generally quite high in all areas, with the exception of the Sea of Okhotsk and the northern Barents Sea where the ice pack was more open.

Overall, extent decreased 170,000 square kilometers (65,600 square miles) during March 2023, compared to the 1981 to 2010 average March decrease of 220,000 square kilometers (84,900 square miles).

Conditions in context

Figure 2a. This plot shows average sea level pressure in the Arctic in millibars for March 2023. 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
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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 March 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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March weather conditions were dominated by persistent high sea level pressure over northern Canada and Greenland, and low sea level pressure over northern Europe and European Russia (Figure 2a). This led to winds from the south and warm conditions over Baffin Bay and western Greenland with temperatures up to 6 to 7 degrees Celsius above average (11 to 13 degrees Fahrenheit) (Figure 2b). Cool conditions extended from Iceland to Franz Josef Land, where temperatures were 4 to 6 degrees Celsius below average (7 to 11 degrees Fahrenheit).

March 2023 compared to previous years

Figure 3. Monthly March ice extent for 1979 to 2023 shows a decline of 2.5 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend for Arctic sea ice extent in March over the 45-year satellite record is 38,900 square kilometers (15,000 square miles) per year, or 2.5 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, March has lost 2.28 million square kilometers (880,000 square miles). This is roughly eight and a half times the size of Colorado or six and a half times the size of Germany.

Arctic sea ice age

Figure 4. The top maps show sea ice age for the week of February 26 to March 4 for (a) 1985  and (b) 2023. The bottom graph is a timeseries of the percent of the sea ice extent within the Arctic Ocean domain (inset map) for the week of February 26 to March 4, 1985, through 2023; color categories are the same as in the maps. Data and images from NSIDC EASE-Grid Sea Ice Age, Version 4 (Tschudi et al., 2019a) and Quicklook Arctic Weekly EASE-Grid Sea Ice Age, Version 1 

Credit: Tschudi et al., 2019b
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An important indicator of sea ice conditions is the sea ice age. As in recent years, there is far less multiyear ice (ice that has survived at least one summer melt season) and the oldest ice (ice that has survived several or more melt seasons) is nearly gone. Multiyear ice covered 33.9 percent of the Arctic Ocean domain in the week of February 26 through March 4, 2023, slightly less than the 34.3 percent during the same week in 2022. This is much less than in the late 1980s when multiyear ice covered 60 to 65 percent of the Arctic Ocean.

A rapid decline in multiyear ice coverage occurred after the then record 2007 September sea ice extent minimum. The multiyear ice coverage has been variable since then, with no significant trend. Overall, there is almost no ice over four years old remaining—it now comprises just 3 percent of the total ice cover. This is the same percentage as last year and contrasts starkly with the late 1980s when 30 to 35 percent of the Arctic Ocean’s ice was older than 4 years. Since 2011, the older-than-four-year-old ice has comprised less than 5.5 percent of the Arctic Ocean. These results are consistent with a new study that evaluated the thickness of ice from moorings in Fram Strait, finding a shift in the ice thickness after 2007 and a decline of the average residence time of ice in the Arctic Ocean.

Autumn in the Antarctic

Figure 5. Antarctic sea ice extent for March 2023 was 2.80 million square kilometers (1.08 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 expanded at a near-average pace in March following its record low extent on February 21. At the end of the month, the Ross Sea and Amundsen Sea were covered again with ice, and significant expansion of ice had begun in the Weddell Sea. However, large areas of the coast, such as the southern Bellingshausen Sea coastline were still ice free; other areas of open water persisted along the boundary between the Amundsen and Ross Seas. Despite regrowth, the Weddell Sea ice cover is well below its typical extent for the end of March.

The March 2023 average sea ice extent around Antarctica was 2.80 million square kilometers (1.08 million square miles), the second lowest March on record. This is 100,000 square kilometers (38,600 square miles) more than the record low extent for March set in 2017.

Ocean circulation changes in the Southern Ocean

Figure 6a. This map shows global ocean circulation, including the major areas of ocean water sinking and upwelling. This is often called the global ocean conveyor belt.

Credit: Modified from National Geographic
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Figure 6b. This schematic diagram of the Southern Ocean portion of the global ocean circulation shows the changes in the recent decades, on the right, relative to the earlier pattern, on the left.

Credit: Lee et al., 2023
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The ocean circulation, which includes well-known surface and subsurface currents and the vertical motion of ocean water, appears to have changed in a major way over the Southern Hemisphere in recent decades. Increased contributions of meltwater from the Antarctic Ice Sheet, mostly from melting at depth due to increased warm deep water reaching the edge of the continent, has added freshwater to the sea currents, making the water less dense. This lighter water flows up to the surface, increasing the stratification in the near-surface layer. Because the stratification is stronger, the vertical ocean circulation has slowed.

These changes reflect changing winds around the continent, resulting from both the ozone hole, which cools the Antarctic stratosphere, increasing the westerly circumpolar winds, and increased carbon dioxide and methane in the air, which warms the tropics, again making the far southern winds stronger.

Great Scott! The Great Lakes in 2023

Figure 7a. This map of the Great Lakes shows ice cover on February 4th, 2023, the date of maximum ice cover for 2023. 

Credit: US National Ice Center
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Figure 7b. This plot shows the departure from average air temperature in the Great Lakes Region at the 925 hPa level, in degrees Celsius, from December 1, 2022, to March 29, 2023, relative to the 1991 to 2020 average. 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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This year, the maximum ice cover area of the Great Lakes, as monitored by the US National Ice Center in Suitland Maryland, was 23.35 percent on February 4, 2023, and for much of the winter ice cover was below 10 percent (Figure 7a). Winter temperatures over the Great Lakes ranged from 0.5 degrees Celsius (1 degree Fahrenheit) above the 1991 to 2020 average over Lake Superior to more than 2 degrees Celsius (4 degrees Fahrenheit) above average over Lake Ontario (Figure 7b).

Although the year-to-year variability in Great Lakes ice cover is high, an analysis led by Jia Wang, an ice climatologist at the National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory (GLERL), found that average winter ice cover on the Great Lakes has declined 69 percent between1973 and 2017, with the greatest losses in Lake Superior and Lake Ontario. However, nearly complete ice cover was seen as recently as 2019. Historically, widespread ice cover over Lake Michigan and Lake Erie (and many other areas) supported ice harvesting for refrigeration.

In memoriam: Josh King

Figure 8. This photograph is a portrait of Josh King.

Credit: Steve Howell, Environment and Climate Change Canada
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It is with great sadness that another colleague of ours recently passed away. Josh King was a dedicated snow field scientist who collected invaluable snow observations throughout the Arctic region during his career. In 2017, NSIDC scientist Julienne Stroeve and others worked with King to collect snow and ice data in the Lincoln Sea, the region of the Arctic known as the Last Ice Area. Stroeve remembers how professional King was in leading the data collection efforts, keeping the team motivated while working tirelessly after returning back to base each night to keep instruments operational and quality control the data collected. It is a great loss for the scientific community to lose a colleague at such a young age.

References

Holling, H. C. 1941. Paddle-to-the-Sea. Boston, Houghton Mifflin

Ice Harvesting in Sandusky

Lee, S. K., R. Lumpkin, F. Gomez, S. Yeager, H. Lopez, F. Takglis, S. Dong, W. Aguiar, D. Kim, and M. Baringer. 2023. Human-induced changes in the global meridional overturning circulation are emerging from the Southern Ocean. Nature Communications Earth and Environment 4, 69, doi:10.1038/s43247-023-00727-3.

National Oceanic and Atmospheric Administration (NOAA) Great Lakes Environmental Research Laboratory (GLERL) Annual Max Ice Cover Animation

Sumata, H., de Steur, L., Divine, D.V. et al. 2023. Regime shift in Arctic Ocean sea ice thickness. Nature 615, 443–449, doi:10.1038/s41586-022-05686-x.

Tschudi, M., W. N. Meier, J. S. Stewart, C. Fowler, and J. Maslanik. 2019a. EASE-Grid Sea Ice Age, Version 4 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center, doi:10.5067/UTAV7490FEPB. Date Accessed 03-31-2023.

Tschudi, M., W. N. Meier, and J. S. Stewart. 2019. Quicklook Arctic Weekly EASE-Grid Sea Ice Age, Version 1 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center, doi:10.5067/2XXGZY3DUGNQ. Date Accessed 03-31-2023.

Wang, J., J. Kessler, F. Hang, H. Hu, A. Clites, and P. Chu. 2017. Great Lakes ice climatology update of winters 2012-2017: Seasonal cycle, interannual variability, decadal variability, and trend for the period 1973-2017. NOAA Technical Memorandum GLERL-170.

Arctic sea ice has likely reached its maximum extent for the year, at 14.62 million square kilometers (5.64 million square miles) on March 6. The 2023 maximum is the fifth lowest in the 45-year satellite record. NSIDC scientists will present a detailed analysis of the 2022 to 2023 winter sea ice conditions in the regular monthly post in early April.

Overview of conditions

Figure 1. This image shows Arctic sea ice extent on March 7, 2023, which was 14.62 million square kilometers (5.64 million square miles) like the extent on March 6, 2023. The March 7 image is being used because of missing data on the prior day’s map. 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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On March 6, 2023, Arctic sea ice likely reached its maximum extent for the year, at 14.62 million square kilometers (5.64 million square miles), the fifth lowest extent in the satellite record. This year’s maximum extent is 1.03 million square kilometers (398,000 square miles) below the 1981 to 2010 average maximum of 15.65 million square kilometers (6.04 million square miles) and 210,000 square kilometers (81,000 square miles) above the lowest maximum of 14.41 million square kilometers (5.56 million square miles) set on March 7, 2017.

The date of the maximum this year, March 6, was six days earlier than the 1981 to 2010 average date of March 12.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of March 6, 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 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
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The ice growth season ended with below average sea ice extent in the Bering Sea, Sea of Okhotsk, Barents Sea, and Labrador Sea. Above average extent was in the Greenland Sea. Extent was well below average in the Gulf of St. Lawrence for a second year in row.

Since the maximum on March 6, extent has dropped about 200,000 square kilometers (77,000 square miles), with losses primarily in Labrador Sea, Gulf of St. Lawrence, and the Barents Sea.

Table 1. Ten lowest maximum Arctic sea ice extents (satellite record, 1979 to present)

For the Arctic maximum, which typically occurs in March, the uncertainty range is ~34,000 square kilometers (13,000 square miles), meaning that extents within this range must be considered effectively equal.

On February 21, Antarctic sea ice likely reached its annual minimum extent of 1.79 million square kilometers (691,000 square miles). This the lowest sea ice extent in the 1979 to 2023 sea ice record, setting a record low for the second straight year.

Please note that this is a preliminary announcement. Changing winds or late-season melt could still reduce the Antarctic ice extent. NSIDC scientists will release a full analysis of the Antarctic and Arctic February conditions in early March.

Overview of conditions

Figure 1. Antarctic sea ice extent for February 21, 2023, was 1.79 million square kilometers (691,000 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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On February 21, 2023, sea ice in the Antarctic reached an annual minimum extent of 1.79 million square kilometers (691,000 square miles), setting a record low in the satellite record that began in 1979. This year’s minimum is 1.05 million square kilometers (405,000 square miles) below the 1981 to 2010 average Antarctic minimum extent. It is 136,000 square kilometers (52,500 square miles) below the previous record low from February 25, 2022. Nearly all of the remaining ice is in the Weddell Sea, with isolated patches along the coasts of Princess Astrid and Princess Ragnild and regions of eastern Wilkes Land and the Pine Island Bay.

The Antarctic minimum extent was reached three days earlier than the 1981 to 2010 median date of February 24. The interquartile range for the date of the Antarctic minimum is February 20 to February 27.

Conditions in context

Figure 2a. The graph above shows Antarctic sea ice extent as of February 21, 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 2013 to 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 2b. This graph shows Antarctic annual sea ice minimum extent, depicted as black diamonds, from 1979 to 2023, based on a 5-day running average of daily extent. The linear trend line is in blue with a 1.0 percent per decade downward trend, which is not statistically significant. A five-year running average is shown in red.

Credit: W. Meier, NSIDC
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This year marks a second consecutive record low in Antarctic sea ice extent (Figure 2a). In recent years, 2017 and 2018 also reached very low extents, third and fourth lowest, respectively. With this series of low years, it is natural to speculate if there is now a downward trend. However, a trend computed over such a short time period is not especially meaningful. Note in this respect that 2013 through 2015 saw near record high minimum extents.

Overall, the downward trend in the annual Antarctic sea ice minimum extent computed over the complete satellite record is 2,800 square kilometers (1,100 square miles) per year, or 1.0 percent per decade relative to the 1981 to 2010 average. This trend is not statistically significant (Figure 2b). This is in stark contrast to the Arctic where the trend in the sea ice minimum is larger in magnitude and has strong statistical significance.

Antarctic sea ice extent appears to have broken the record low set last year. With a couple more weeks likely left in the melt season, the extent is expected to drop further before reaching its annual minimum. Much of the Antarctic coast is ice free, exposing the ice shelves that fringe the ice sheet to wave action and warmer conditions.

Overview of conditions

Figure 1a. This map of Antarctica shows many low areas of sea ice concentration, depicted as darker blues, surrounding the continent, rendering extent likely to decrease in the coming days or weeks. Antarctic sea ice extent for February 13, 2023, was 1.91 million square kilometers (737,000 square miles). The orange line shows the 1981 to 2010 median 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 Antarctic sea ice extent as of February 13, 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 2013 to 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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On February 13, 2023, Antarctic sea ice extent fell to 1.91 million square kilometers (737,000 square miles) (Figure 1a). This set a new record low, dropping below the previous record of 1.92 million square kilometers (741,000 square miles) set on February 25, 2022 (Figure 1b). This year represents only the second year that Antarctic extent has fallen below 2 million square kilometers (772,000 square miles). In past years, the annual minimum has occurred between February 18 and March 3, so further decline is expected.

Conditions in context

Figure 2. This graph shows Antarctic annual sea ice minimum extent, depicted as black diamonds, from 1979 to 2023, based on a 5-day running average of daily extent. The grey diamond data point depicts the 2023 minimum, which is still preliminary, with further loss expected. The linear trend line is in blue with a 0.9 percent per decade downward trend, which is not statistically significant. A five-year running average is shown in red. As the Antarctic melt season is still in progress, depicted as a grey downward arrow, the linear trend and running average will change slightly.

Credit: W. Meier, NSIDC
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Extent has tracked well below last year’s melt season levels since mid-December. As noted in our previous post, a positive Southern Annular Mode has led to stronger-than-average westerly winds. Along with a strong Amundsen Sea Low, the weather conditions have brought warm air to the region on both sides of the Antarctic Peninsula. This has largely cleared out the ice cover in the Amundsen and Bellingshausen Seas, and reduced the sea ice extent in the northwestern Weddell Sea. Sea ice is patchy and nearly absent over a long stretch of the Pacific-facing coastline of Antarctica.  Earlier studies have linked low sea ice cover with wave-induced stresses on the floating ice shelves that hem the continent, leading to break up of weaker areas.

Antarctic sea ice extent has been highly variable over the last several years. While 2022 and 2023 have had record low minimum extent, four out of the five highest minimums have occurred since 2008. Overall, the trend in Antarctic minimum extent over 1979 to 2023 is near zero. The current downward linear trend in the Antarctic minimum extent from 1979 to 2023 is 2,400 square kilometers (930 square miles) per year, or 0.9 percent per decade, which is currently not statistically significant. Nevertheless, the sharp decline in sea ice extent since 2016 has fueled research on potential causes and whether sea ice loss in the Southern Hemisphere is developing a significant downward trend.

Arctic sea ice extent rose at a slower than average rate through January, and continued to be below the lower interdecile range. By the end of the month, sea ice reached the second lowest extent in the satellite record. Meanwhile, Antarctic extent remained at record low levels. Combined, the two hemispheres set a record low for total global sea ice extent, yet this does not signify a trend necessarily and may be caused by weather-related variability.

Overview of conditions

Figure 1a. Arctic sea ice extent for January 2023 was 13.35 million square kilometers (5.15 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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Figure 1b. The graph above shows Arctic sea ice extent as of February 5, 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 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
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The January 2023 average Arctic sea ice extent was 13.35 million square kilometers (5.15 million square miles), the third lowest January in the satellite record (Figure 1a). January extent was 1.07 million square kilometers (413,000 square miles) below the 1981 to 2010 average of 14.42 million square kilometers (5.57 million square miles), but 270,000 square kilometers (104,000 square miles) above the record low set in January 2018.

The daily rate of increase in extent was near average through the first half of the month, but slowed during the second half, and extent slightly declined near the end of the month (Figure 1b). Such short-term declines are not unusual in winter and typically reflect responses to weather patterns. Nevertheless, by the end of the month, the overall daily extent tracked at second lowest in the satellite data record. Overall, extent increased 1.09 million square kilometers (421,000 square miles) during January 2023, compared to the 1981 to 2010 average January increase of 1.33 million square kilometers (514,000 square miles).

Regionally, extent remained particularly low in the Barents Sea, and below average extent was also found in the Sea of Okhotsk, the Bering Sea, and the Gulf of St. Lawrence.

Conditions in context

Figure 2a. This plot shows average sea level pressure in the Arctic in millibars for January 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
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 January 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
High-resolution image

The sea level pressure pattern for January featured high pressure over the Pacific sector of the Arctic Ocean (Figure 2a). This feature is known as the Beaufort High and is common in winter and spring. The location of the high varies, but on average it is centered over the Beaufort Sea and drives the Beaufort Gyre, which brings ice from north of Greenland and the Canadian Arctic Archipelago through the Beaufort and into the Chukchi Sea. By contrast, over on the Atlantic side of the Arctic, low pressure dominated in the Barents Sea region. As a result, relatively warm air from the south moved into the Barents Sea region, leading to air temperatures at the 925 millibar level (approximately 2,500 feet above the surface) more than 6 degrees Celsius (11 degrees Fahrenheit) above average near Svalbard (Figure 2b). The lack of sea ice in the Barents Sea likely also contributed to above average air temperatures. Elsewhere, air temperatures were above average over most of the Arctic Ocean, with departures from average ranging from 1 degree Celsius (2 degrees Fahrenheit) to 5 degrees Celsius (9 degrees Fahrenheit).

January 2023 compared to previous years

Figure 3. Monthly January ice extent for 1979 to 2023 shows a decline of 3.0 percent per decade.

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

The downward linear trend in January sea ice extent over the 44-year satellite record is 42,500 square kilometers (16,400 square miles) per year, or 3.0 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, January has lost 1.89 million square kilometers (730,000 square miles). This is equivalent to about seven times the size of Colorado or about twice the size of Germany.

Antarctic sea ice at record lows for January

Figure 4a. Antarctic sea ice extent for January 2023 was 3.23 million square kilometers (1.25 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

Figure 4b. This maps shows Antarctic sea ice concentration for January 2023. 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 maintained record lows for this time of year. On February 1, 2023, the extent was 2.26 million square kilometers (873,000 square miles). This is 270,000 square kilometers (104,000 square miles) below the previous February 1 record low in 2017, and  310,000 square kilometers (120,000 square miles) above the record seasonal minimum in extent that occurred on February 25, 2022. Regionally, extent was particularly low in the Amundsen, Bellingshausen, and Ross Seas (Figure 4a). Typically, sea ice is still present along most of the coastline from the eastern Ross Sea to the Antarctic Peninsula, but this year, most of that coast is largely ice free. Extent is also below average along the Wilkes Land coast in East Antarctica, but near average elsewhere around the continent. Large areas of low concentration sea ice are in the Weddell, Ross, and Amundsen Sea ices (Figure 4b). These areas are likely to melt out before the minimum for 2023 is reached, which is expected to occur late this month or in early March.

Weather conditions around Antarctica have been characterized by stronger-than-average westerly winds (a positive Southern Annular Mode index) and a strong and eastward-positioned Amundsen Sea Low. Air temperatures at the 925 millibar level (about 2,500 feet above sea level) have been 1 to 2 degrees Celsius (2 to 4 degrees Fahrenheit) above average since November in a broad area of the coast stretching clockwise from the eastern Wilkes Land through the Ross and Amundsen Sea, and over most of the Weddell Sea. However, warm ocean waters just below the surface layer are also thought to be playing a role in the general downward trend of Antarctic sea ice since 2016 (Zhang et al., 2022).

The January 2023 average Antarctic extent of 3.23 million square kilometers (1.25 million square miles) is the lowest January extent in the satellite record, below the previous January record low of 3.78 million square kilometers (1.46 million square miles) set in 2017. The downward linear trend in January sea ice extent is 6,400 square kilometers (2,500 square kilometers) per year or 1.3 percent per decade relative to the 1981 to 2010 average.

Arctic freeze/thaw from above and below

A key component in the seasonal and interannual evolution of Arctic sea ice is the timing of melt onset and freeze up. Surface melt and freeze up can be obtained from satellite passive microwave observations but satellite observations do not provide information about what is happening under the ice. The length of the melt season is much longer underneath sea ice as a result of ocean heat. A recent study evaluated data collected from sea ice mass balance buoys (IMBs) and upward looking sonar (ULS) instruments to gain insights on the seasonality of ice melt and freeze up below the ice. Over the period from 2001 to 2018, Lin and colleagues found that in the Beaufort Sea, the bottom melt onset began 17 days before the surface melt. By contrast, in the central Arctic the timing of the melt onset of the top and bottom of the ice was similar. The freeze up of the bottom of the ice began about three weeks after the surface started to freeze. The researchers also found that bottom melt onset occurred about a week earlier during the 2010 to 2018 period compared to the 2001 to 2009 period, because of rising ocean temperatures. Bottom freeze up began one to two weeks earlier in the later period compared to the earlier period because thinner ice allowed faster heat loss from the ocean.

References

Arctic Sea Ice Melt Data Set

Bliss, A. C., M. Anderson, and S. Drobot. 2022. Snow Melt Onset Over Arctic Sea Ice from SMMR and SSM/I-SSMIS Brightness Temperatures, Version 5 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi:10.5067/TRGWQ0ONTQG5.

Lin, L., R. Lei, M. Hoppmann, D. K. Perovich, and H. 2022. Changes in the annual sea ice freeze–thaw cycle in the Arctic Ocean from 2001 to 2018. The Cryosphere, 16, 4779–4796, doi:10.5194/tc-16-4779-2022.

Steele, M., A. C. Bliss, G. Peng, W. N. Meier, and S. Dickinson. 2019. Arctic Sea Ice Seasonal Change and Melt/Freeze Climate Indicators from Satellite Data, Version 1 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi:10.5067/KINANQKEZI4T.

Zhang, L., T. L. Delworth, X. Yang, et al. 2022. The relative role of the subsurface Southern Ocean in driving negative Antarctic Sea ice extent anomalies in 2016–2021. Communications Earth and Environment 3, 302. doi:10.1038/s43247-022-00624-1.

November’s rate of sea ice growth in the Arctic was near average. Several of the peripheral seas have open water areas late into the autumn season. Warm air temperatures persist in the northern North Atlantic and northwestern Europe. In Antarctica, sea ice extent is low, and persistent low air pressure in the Amundsen Sea has created a somewhat unusual sea ice distribution.

Overview of conditions

Figure 1. Arctic sea ice extent for November 2022 was 9.71 million square kilometers (3.75 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 November 2022 average Arctic sea ice extent was 9.71 million square kilometers (3.75 million square miles). This is the eighth lowest in the satellite record for the month (Figure 1a). Extent was 990,000 square kilometers (382,000 square miles) below the 1981 to 2010 average of 10.7 million square kilometers (4.13 million square miles) and 1.05 million square kilometers (405,000 square miles) above the record November low set in 2016 of 8.66 million square kilometers (3.34 square miles).

Overall for the month, ice extent increased at a near-average rate, but with much faster-than-average growth for the first week balanced by slow growth over the remainder of the month.  Open water conditions persisted in part of the Chukchi Sea, approximately two weeks late in the season relative to the 1981 to 2010 average. Similarly, ice extent has remained below average in the Kara and Barents Seas, and in Hudson Bay. Ice in the Bering Sea is limited to Norton Sound and Kotzebue Sound. The coast of Svalbard in the far northern North Atlantic remains ice free at the end of the month.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of December 4, 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

Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for November 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 2c. This plot shows average sea level pressure in the Arctic in millibars for November 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

Warm conditions prevailed in the northern North Atlantic and over northwestern Europe (Figure 2b). Air temperatures at the 925 mb level (approximately 2,500 feet above the surface) over much of the Greenland Sea (between Norway and Greenland) were 3 to 6 degrees Celsius (5 to 11 degrees Fahrenheit) above average. Temperatures in the northern Yukon and northeastern Alaska regions were about 4 degrees Celsius (7 degrees Fahrenheit) above average. However, the Siberian side of the Arctic experienced temperatures 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) below average. The Baffin Bay region had temperatures 3 to 5 degrees Celsius (5 to 9 degrees Fahrenheit) below average.

Atmospheric circulation for the month was characterized by a strong low sea level pressure centered south of Iceland (Figure 2c). The counterclockwise circulation around this low is largely responsible for the widespread warm conditions in the northern North Atlantic and the cooler conditions in Baffin Bay. By contrast, the pressure field over the Arctic Ocean was fairly flat, indicating weak winds overall.

November 2022 compared to previous years

Figure 3. Monthly November ice extent for 1979 to 2022 shows a decline of 4.8 percent per decade.

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

The downward linear trend in November sea ice extent over the 45-year satellite record is 51,800 square kilometers (20,000 square miles) per year, or 4.8 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 1.5 times the size of Alaska.

Bloomin’ down under

Figure 4. These conceptual models show how the sun stimulates plankton grown at, near the surface, and on the sea floor. When coastal areas are ice free in early to mid-summer, more light penetrates through the water column to feed a plankton bloom at deeper depths. 

Credit: Shiozaki et al. 2022
High-resolution image

A new study by Shiozaki et al. (2022) reveals that plankton on the seabed in the Arctic Ocean is increasingly in bloom, as longer ice-free periods near the coast allow more light to reach the shallow coastal ocean bottom and stimulate growth (Figure 4). Since this represents an expansion of the area and volume that plankton can thrive, it has implications for bio-productivity in the Arctic food chain and sequestration of carbon by the ocean.

As sunshine returns to the Arctic in spring, it stimulates plankton growth at or near the surface—a typical plankton bloom. However, plankton growth is often limited by the nutrient level in the water column, and in many areas the surface bloom consumes all the nutrients in the top ocean layer. If the shallow coastal areas of the Arctic become ice free in early to mid-summer, more light can penetrate through the water column. This provides energy to plankton that have descended in the water column to depths where there are still abundant nutrients, resulting in a bloom on the sea floor.

The regions where this appears to be occurring are in the Chukchi Sea, but it could potentially occur over wide regions of the Siberian and Alaskan shallow continental shelf.

Antarctica’s spring

Figure 5. Antarctic sea ice extent for November 2022 was 15.06 million square kilometers (5.81 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 is declining rapidly now in response to seasonal warming. Sea ice extent is particularly low in the Bellingshausen Sea, where much of the eastern portion adjacent to the Antarctic Peninsula has been ice free for much of November. By sharp contrast, ice extent in the Amundsen Sea just west of the Bellingshausen, has extended much farther to the north than is typical and is the one area of the Antarctic sea ice that has above-average ice extent.

This is explained by the sea level pressure pattern. A strong low over much of the Amundsen Sea and eastern Ross Sea has driven a clockwise air circulation that has brought warm air from the north onto the western Peninsula region, and cold air from the continental ice sheet northward in the Amundsen Sea.

This low-pressure region is a well-known feature of Antarctica’s climate, and its strength is often measured by a climate index called the Antarctic Oscillation (AAO). The AAO index has been strongly positive for the entire month of November, indicating especially strong low pressure in the Amundsen Sea. In fact, the index has been generally positive for the entire year, and has become more positive over the past several decades.

Further reading

Shiozaki, T., A. Fujiwara, K. Sugie, K., S. Nishino, A. Makabe, and N. Harada. 2022. Bottom‐associated phytoplankton bloom and its expansion in the Arctic Ocean. Global Change Biology, 28(24), 7286-7295, doi:10.1111/gcb.16421.

After reaching the minimum on September 18, Arctic sea ice extent has been steadily increasing. With the passage of the equinox, the sun has set at the North Pole. September average ice extent ended up tying with 2010 for eleventh lowest in the satellite record.

Overview of conditions

Figure 1a. Arctic sea ice extent for September 2022 was 4.87 million square kilometers (1.88 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 October 3, 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 September 2022 average Arctic sea ice extent was 4.87 million square kilometers (1.88 million square miles), tying with 2010 for eleventh lowest in the satellite record (Figure 1a). Extent was 1.54 million square kilometers (595,000 square miles) below the 1981 to 2010 average and 1.30 million square kilometers (502,000 square miles) above the record minimum set in 2012. The annual minimum extent was reached on September 18 and the autumn freeze-up is now well underway.

Ice extent declined at a faster than average rate from the beginning of the month until the minimum was reached on September 18 (Figure 1b). This resulted in a tie for the tenth lowest minimum daily extent in the satellite record. Extent was below average in all sectors of the Arctic Ocean, apart from the northern shore of the Canadian Arctic Archipelago, where ice is almost invariably pushed up against the coast by winds and ocean currents. A tongue of ice continued to extend southward in the East Siberian Sea, and a portion of ice floes broke away from the main pack ice off the tip of that tongue. An open water passage has nevertheless persisted along the Northern Sea Route. The Northwest Passage has started to freeze up, particularly the northern route through Parry Channel, but much of the Canadian Archipelago remained essentially ice free through the end of the month.

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 September 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 September 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 September at the 925 millibar level (approximately 2,500 feet above the surface) were above average over the North American side of the Arctic and near average or below average over most of the Eurasian side (Figure 2a). Averaged sea level pressure for September featured low pressure extending across Eurasia, Alaska, and the Canadian Arctic Archipelago, with high pressure over the central Arctic Ocean, notably north of the Canadian Arctic Archipelago (Figure 2b). The low pressure over Alaska reflects the passage of an extremely strong storm during the middle of the month that caused extensive damage and flooding to the town of Nome and surrounding areas.

September 2022 compared to previous years

Figure 3. Monthly September ice extent for 1979 to 2022 shows a decline of 12.3 percent per decade.

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

The downward linear trend in September sea ice extent over the 44-year satellite record is 79,100 square kilometers (30,500 square miles) per year, or 12.3 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, September has lost 3.59 million square kilometers (1.39 million square miles). This is equivalent to about twice the size of Alaska.

Summer 2022 in review

Figure 4a. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, from June to August 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 4b. This plot shows average sea level pressure in the Arctic in millibars from June to August 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

Figure 4c. The upper left map shows ice age distribution toward the end of the melt season for 1985. The upper right map shows the end of the 2022 melt season. The bottom graphs shows sea ice age extent for multiyear ice, as depicted by the black line, and 4+ year-old ice, as depicted by the red line, for the Arctic Ocean region. The inset identifies the region of interest. Note the ice age product does not include ice in the Canadian Archipelago.

Credit: Tschudi et al., 2019
High-resolution image

Figure 4d. This graph shows the annual change of multiyear and 4+ year-old ice over the summer melt season (mid-March to the September minimum) for 1985 to 2022. The black line depicts multiyear ice; the red line depicts 4+ year-old ice.

Credit: Tschudi et al., 2019
High-resolution image

Figure 4e. This graph shows weekly sea ice extent in the Parry Channel, the red highlighted region in inset, based on Canadian Ice Service analyses for last four years, 2019 to 2022, the 2011 record low year, and the 1991 to 2020 average.

Credit: Steve Howell, Environment and Climate Change Canada
High-resolution image

Figure 4f. Clink on this animation to view the 2022 seasonal ice retreat. Images are from sea ice concentration data from NSIDC’s Sea Ice Index. The timeline is not uniform. The animation shows one image per week from May 2 to August 1, and then every other day through August, and every day in September until September 18, the seasonal ice minimum.

Credit: Michon Scott, NSIDC
High-resolution image

The summer 2022 melt season had some noteworthy highlights. Extent loss was less extreme than recent years through much of the summer; for the first time since 2014, extent briefly sat within the 1981 to 2010 lower interdecile range. However, late season ice loss was strong, pushing the September average to eleventh lowest in the passive microwave satellite record. No region of the Arctic was extreme in terms of how far north the ice edge retreated, though compared to average conditions, the ice edge was quite far north in the Laptev and Chukchi Seas. Surface melt onset was also variable, with earlier-than-average melt along the Siberian coast, particularly in the Kara and Barents Seas, but later-than-average melt in much of the central Arctic Ocean.

Air temperatures at the 925 millibar level (about 2,500 feet above sea level) were above average over much of the Arctic Ocean, but not as extreme as in many recent summers. Much of the Arctic Ocean experienced summer (June, July, August) temperatures 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above average (Figure 4a). Only in parts of the Barents Sea did 2022 summer air temperatures reach up to 4 degrees Celsius (7 degrees Fahrenheit) above average. In the southern Chukchi and northern Bering Seas, temperatures were 1 degree Celsius (2 degrees Fahrenheit) below average.

During June through August, average sea level pressure was low over much of the Siberian side of the Arctic, as well as over eastern Canada, and east of Greenland, with a small and weak Beaufort Sea High that primarily manifested itself in June (Figure 4b). Summer-averaged pressure gradients were slack, particularly in July and August, albeit with intermittent stronger gradients caused by passing weather systems. Weak pressure gradients resulted in relatively weak surface winds and sea ice circulation through much of the summer.

Of particular note was the formation of polynyas north of the Kara Sea, at about 87 degrees North latitude. These started to form in early July and were observed intermittently through the end of August. These unusual polynyas likely opened at least in part because of divergent ice motion, but their formation and general persistence is also an indication of thin, young, and uncompacted ice. It is also possible that deep ocean waters were churned toward the surface as currents flowed over the Lomonosov Ridge beneath some of the polynya areas.

The distribution of sea ice age at the end of summer 2022 shows a dominance of first and second-year ice (Figure 4c). Some of this second-year ice extends south into the East Siberian Sea and is one reason why the Northern Sea Route maintained ice until later in the summer. A thin ribbon of old ice (3 to 4 and 4+ years age) extends along the northern shore of the Canadian Arctic Archipelago. The summertime loss of the multiyear ice has generally increased since the mid 1980s, but with large variations from one summer to the next (Figure 4d). The 4+ year-old ice shows less summertime change, especially since 2012, because so little of that ice remains in the Arctic. The most notable feature in both ice age classes is the large spike in loss during the 2007 summer.

The evolution of sea ice concentration during the 2022 melt season is presented in an animation, which begins on May 2 and ends at the sea ice minimum on September 18 (Figure 4f). Rapid early loss is noticeable in the Kara Sea with large retreats also occurring in the Laptev and Beaufort Seas. By August, a tongue of somewhat older and thicker ice is left behind in the East Siberian Sea. Retreat was generally ahead of the average date for ice extent through the summer. Also shown is the unusually persistent low sea ice concentration in the high Arctic north of the Severnaya Zemlaya islands, eventually leading to the opening of two high-latitude polynyas in late August into early September. Melt events are shown as brief drops in concentration, but the regions around the polynyas remained low throughout the second half of the summer.

The Northwest Passage (NWP)—a shortcut between Europe and Asia through the channels of the Canadian Arctic Archipelago—was the dream of explorers and financiers for centuries. The southern NWP route was first navigated by Roald Amundsen over three summers, 1905 to 1908. In recent years, his circuitous route, winding through narrow and shallow channels, has often opened for at least part of the summer. However, even in recent years, the more direct northern route through Parry Channel, with wide and deep channels more suitable for shipping, has remained choked with ice. This is partly because of an influx of thick, multiyear ice into the channel from the Arctic Ocean to the north. This year the northern route largely opened. While operational analysis showed the region with 10 to 80 percent ice cover, high resolution maps of the ice cover, indicated a continuous path through open water starting in late August until mid-September. Overall, the ice area in the northern route reached the fourth lowest in the 55-year record of Canadian Arctic sea ice conditions analyzed by the Canadian Ice Service; the NWP information was provided by Steve Howell of Environment and Climate Change Canada (Figure 4e).

Top ten lowest sea ice extents in northern route of the Northwest Passage

The view down south

Figure 5. The graph above shows Antarctic sea ice extent as of October 3, 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
High-resolution image

As the Arctic makes its journey into autumn, Antarctic sea ice extent is nearing its winter maximum. On September 16, extent stood at 18.19 million square kilometers (7.02 million square miles), which may represent the seasonal maximum. However, extent may yet rise above that value. After record and near-record low extent earlier in the year, late ice growth increased the extent within the inter-decile range by mid-September.

Antarctic sea ice extent has exhibited extreme interannual variability with record highs and record lows within the past decade. There is also strong regional variability, with some areas showing long-term trends of ice loss, with others showing gains. One region with a notable downward trend in extent is the Bellingshausen Sea, west of the Antarctic Peninsula. The Peninsula region has also experienced a strong multi-decade warming trend, which has resumed after a decade-long hiatus. One factor in these changes is a strengthening of the Amundsen Low the brings southward winds to the region, which raise air temperatures and compact the ice. A new study by Dalaiden et al. suggests that this Amundsen Low strengthening is caused by an anthropogenic forcing, and a coupling to the general temperature pattern and trends in the Pacific Ocean.

Update

On October 5, 2022, the Arctic Sea Ice News & Analysis team decided to add the animation of sea ice loss through the melt season and corresponding text (Figure 4f).

References

Dalaiden, Q., A. P. Schurer, M. C. Kirchmeier-Young, H. Goosse, and G. C. Hegerl, G. 2022. West Antarctic surface climate changes since the mid-20th century driven by anthropogenic forcing. Geophysical Research Letters, 49, e2022GL099543. doi:10.1029/2022GL099543.

Tschudi, M., W. N. Meier, J. S. Stewart, C. Fowler, and J. Maslanik. 2019. EASE-Grid Sea Ice Age, Version 4 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi:0.5067/UTAV7490FEPB. Date Accessed 10-04-2022.

Tschudi, M., W. N. Meier, and J. S. Stewart. 2019. Quicklook Arctic Weekly EASE-Grid Sea Ice Age, Version 1 [Data Set]. Boulder, Colorado USA. NASA National Snow and Ice Data Center Distributed Active Archive Center. doi:10.5067/2XXGZY3DUGNQ. Date Accessed 10-04-2022.

On September 18, Arctic sea ice likely reached its annual minimum extent of 4.67 million square kilometers (1.80 million square miles). The 2022 minimum is tied for tenth lowest in the nearly 44-year satellite record, with 2018 and 2017. The last 16 years, from 2007 to 2022, are the lowest 16 sea ice extents in the satellite record.

In the Antarctic, sea ice extent has hit record lows through most of the growth season. Starting in early August, sea ice began expanding rapidly, exemplifying the strong degree of variability in Southern Hemisphere sea ice. As such it is too early to assume that the maximum has been reached as storms may still expand or compact the extended ice edge. The maximum for Antarctic sea ice typically occurs in late September or early October.

Please note that this is a preliminary announcement. Changing winds or late-season melt could still reduce the Arctic ice extent, as happened in 2005 and 2010. NSIDC scientists will release a full analysis of the Arctic melt season, and discuss the Antarctic winter sea ice growth, in early October.

Overview of conditions

Figure 1. Arctic sea ice extent for September 18, 2022, was 4.67 million square kilometers (1.80 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
High-resolution image

On September 18, sea ice reached its annual minimum extent of 4.67 million square kilometers (1.80 million square miles) (Figure 1), tying for tenth lowest with 2018 and 2017. In response to the setting sun and falling temperatures, ice extent has begun expanding and will continue through autumn and winter. However, a shift in wind patterns or a period of late season melt could still push the ice extent lower.

The minimum extent was reached four days later than the 1981 to 2010 median minimum date of September 14. The interquartile range of minimum dates is September 11 to September 19.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent on September 18, 2022, along with several other recent years and the record minimum set in 2012. 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

This year’s minimum set on September 18 was 1.28 million square kilometers (494,000 square miles) above the satellite-era record minimum extent of 3.39 million square kilometers (1.31 million square miles), which occurred on September 17, 2012 (Figure 2). It is also 1.55 million square kilometers (598,000 square miles) below the 1981 to 2010 average minimum extent, which is equivalent to twice the size of Texas.

In the 44-year-satellite record, 16 of the lowest minimums have all occurred in the last 16 years.

The overall, downward trend in the minimum extent from 1979 to 2022 is 12.6 percent per decade relative to the 1981 to 2010 average. The loss of sea ice is about 78,500 square kilometers (30,300 square miles) per year, equivalent to losing the size of the state of South Carolina or the country of Austria annually.

Sixteen lowest minimum Arctic sea ice extents (satellite record, 1979 to present)

Values within 40,000 square kilometers (15,000 square miles) are considered tied. The 2021 value has changed from 4.72 to 4.77 million square kilometers (1.84 million square miles) when final analysis data updated near-real-time data. 

Further reading

NASA visualization of 2022 Arctic sea ice minimum extent

Summer in the Arctic is drawing to a close, and sea ice extent is likely to remain higher than in recent years. Several polynyas have formed poleward of 85 degrees North within the pack as well as areas near the thin ice edge. While some thin ice can still be found in the Northern Sea Route and southern Northwest Passage, both appear to be largely open. The northern deep water Northwest Passage route also appears to be largely open. Antarctic sea ice has remained at record or near-record low extent for the month.

Overview of conditions

Figure 1a. Arctic sea ice extent for August 2022 was 5.99 million square kilometers (2.31 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. This map shows open water within the ice pack, known as a polynya, poleward of 85 degrees North. Sea ice concentration data are from Advanced Microwave Scanning Radiometer 2 (AMSR2) imagery.

Credit: University of Bremen
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Average Arctic sea ice extent for August 2022 was 5.99 million square kilometers (2.31 million square miles), ranking thirteenth lowest in the satellite record (Figure 1a) and 1.21 million square kilometers (467,000 square miles) below the 1981 to 2010 average. Ice extent tracked below the interdecile range of the satellite record through the month, and the total ice loss through the month was 1.79 million square kilometers (691,000 square miles). Extent remained particularly low in the Laptev and Chukchi Seas. As seen in the Advanced Microwave Scanning Radiometer 2 (AMSR2) imagery, areas of low concentration ice that started to develop poleward of 85 degrees North in July developed into areas of open water within the pack ice, or polynyas (Figure 1b). These features are much further north than is typical. On the Atlantic side, the ice edge remained north of Svalbard and Franz Josef Land, continuing the pattern seen for most of the season.

The rate of decline for Arctic sea ice extent was near average for most of the month at about 60,000 square kilometers (23,000 square miles) per day, but briefly increased late in the month to near 85,000 square kilometers (33,000 square miles) per day. During the second half of August, ice loss was mostly in the East Siberian Sea and the northern Chukchi Sea.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of September 05, 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 August 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 August 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) were generally 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above 1991 to 2020 reference period (Figure 2b). Conditions in the Barents Sea and southern Kara Sea were particularly warm, ranging up to 4 degrees Celsius (7 degrees Fahrenheit) above average. However, temperatures over the Bering Sea and the Denmark Strait (between Iceland and Greenland) were slightly below average.

The sea level pressure pattern for August favored winds from the south and west toward Europe, and cool air moving out of the Arctic over the Laptev Sea coast in Siberia (Figure 2c). Low air pressure over Alaska led to winds from the north over the Bering Sea, consistent with the below-average temperatures in that area.

While the summer melt season is nearly over, the forecast for early September is for above-average air temperatures over the central Arctic. Coupled with the thin and dispersed sea ice cover, and residual heat in the upper ocean where low sea ice concentration permitted some solar warming earlier in the summer, we may see an expansion of the polynyas near the North Pole for a time in early September.

August 2022 compared to previous years

Figure 3. Monthly August ice extent for 1979 to 2022 shows a decline of 10.1 percent per decade.

Credit: National Snow and Ice Data Center
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The downward linear trend in August sea ice extent over the 44-year satellite record is 72,500 square kilometers (28,000 square miles) per year, or 10.1 percent per decade relative to the 1981 to 2010 average. Based on the linear trend, since 1979, August has lost 1.7 million square kilometers (656,000 square miles). This is equivalent to about the size of Alaska.

North by northwest

Figure 4. These graphs show sea ice area for the recent summer season in the two most common paths of the Northwest Passage through the Canadian Archipelago. The top graphic shows a time series plot of total sea ice area for 2022, 2021, 2020, 2019, 2011, and the 1991 to 2020 average within the northern route of the Northwest Passage. The lower graphic shows sea ice area for the southern route for the same time period.

Credit: Data from the Canadian Ice Service provided by our colleague Steve Howell of Environment and Climate Change Canada (ECCC)
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As of the August 27, sea ice area in the northern (deep water) route of the Northwest Passage (NWP) was tracking well below the 1991 to 2020 average (Figure 4, top) but above 2011 record low conditions. High concentrations of multi-year ice were still present in some areas. Ice area in the southern route (Amundsen’s route in 1905) was also tracking well below the 1991 to 2020 average (Figure 4, bottom). The southern route was almost sea ice-free as of late August except for some low concentration first-year ice in the vicinity of Victoria Strait. The northern route of the Northwest Passage is considered to eventually be more viable for shipping. Mudruyk and team discuss the impact of the current warming trend on potential shipping through the Canadian Arctic, noting large increases in navigability of the NWP and other parts of the Arctic with 2 degrees Celsius (4 degrees Fahrenheit) global warming above pre-industrial levels. Even non-ice strengthened vessels may have a 15-day season of operation in the northern NWP according to their study. By contrast, the Northern Sea Route has been nearly free of ice for at least part of August and September for most of the past decade, and it is used increasingly for shipping both within the Russian Arctic and from Arctic ports to the Far East.

Arctic sea surface temperatures

Figure 5. This map shows sea surface temperatures (SSTs) for the Arctic and much of the northern Atlantic and Pacific Oceans, as well as the peripheral seas in the northern hemisphere. Data shows SSTs on August 23, 2022. Extremely warm ocean conditions exist along parts of the Siberian coast, but cooler than average conditions are found in the Bering Sea and Norwegian Sea.

Credit: Climate Reanalyzer, University of Maine
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According to our colleague, Mike Steele, at the University of Washington Polar Science Center, Pan-Arctic sea surface temperatures (SSTs) in late August are generally above average relative to the 1971 to 2000 reference period (Figure 5). However, Alaskan Arctic SSTs this year are lower than average, likely because the relatively late sea ice retreat limited warming through solar heating. Meanwhile, SSTs on the Russian continental shelf from the eastern Barents Sea to the western East Siberian Sea are far above average. Ice retreat was early there, allowing the upper ocean to warm more strongly through solar heating, with advection of warm air in the southern Barents and Kara Seas (Figure 2 in the August 17 post) perhaps also playing a role.

Reference

Mudryk, L., J. P. Dawson, S. E. L. Howell, C. Derksen, T. Zagon, and M. Brady. 2021. Impact of 1°, 2°, and 4°C of global warming on ship navigation in the Canadian Arctic. Nature Climate Change,11, 673–679, doi:10.1038/s41558-021-01087-6.