As of July 13, Arctic sea ice extent was tracking just below the 2012 record and very close to 2020, the years with the lowest and second lowest (tied with 2007) minimum ice extent in the satellite record. The Laptev Sea is essentially ice free. Multiyear ice persists close to the Alaskan shoreline near Utqiaġvik (formerly Barrow), and low atmospheric pressure persists over the central Arctic Ocean, forcing a pronounced cyclonic (counterclockwise) ice motion pattern.

Overview of conditions

Figure 1. Arctic sea ice extent for July 13, 2021 was 7.95 million square kilometers (3.07 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

Figure 1b. This map shows Arctic sea ice concentration based on data from the Advanced Microwave Scanning Radiometer 2 (AMSR2) data. Yellows indicate sea ice concentration of 75 percent, dark purples indicate sea ice concentration of 100 percent.

Credit: University of Bremen
High-resolution image

Sea ice loss continued at a brisk pace through the first two weeks of July. On July 13, Arctic sea ice extent stood at 7.95 million square kilometers (3.07 million square miles). This is 1.98 million square kilometers (764,000 square miles) below the 1981 to 2010 average. This extent is also just below the 2012 record and very close to 2020, the years with the lowest and second lowest (tied with 2007) minimum in the satellite record, respectively. By July 13, the Laptev Sea area, which began melting out much earlier than is typical for this time of year, was almost completely free of sea ice. This is broadly similar to last summer’s pattern, which holds the record for the lowest sea ice extent within the Laptev Sea at this time of year. The Northern Sea Route along the Russian coast is not yet ice free, and not really even close; as shown in the Advanced Microwave Scanning Radiometer 2 (AMSR-2) imagery from the University of Bremen (Figure 1b), a substantial area of high concentration ice persists north of the Taymyr Peninsula and west of the Severnaya Zemlaya islands (the traditional “choke point”). The Northwest Passage through the channels of the Canadian Arctic Archipelago also remains choked with ice. Continuing the pattern discussed in our previous post, sea ice remains close to the shore north of Utqiaġvik, AK.

Conditions in context

Figure 2a. This plot shows average sea level pressure in the Arctic in millibars from July 1 to 12, 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

Figure 2b. This plot shows the direction of sea ice motion for the period between June 25 and July 1, 2021. Data are from the Quicklook Arctic Weekly EASE-Grid Sea Ice Motion Vector, a NASA NSIDC DAAC data product.

Credit: M. Tschudi, W. Meier, and Stewart/NASA National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC)
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, from July 1 to 12, 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

A pattern of unusually strong low pressure near the North Pole continued to dominate the average atmospheric circulation pattern for the first 12 days of July (Figure 2a). The pressure at the center of the system was up to 15 millibars below average. It is not unusual to see such a persistent pattern of low pressure set up near the pole in summer, but the center of low pressure is usually located towards the Bering Strait side of the central Arctic. Past research has shown that the low-pressure region is maintained by cyclones moving into the region from Eurasia and as well as the generation of lows (cyclogenesis) over the Arctic Ocean itself.

This persistent low pressure pattern has had a pronounced effect on sea ice motion based on NSIDC DAAC data (Figure 2b).  Since winds blow counterclockwise around low pressure centers (in the Northern Hemisphere) the sea ice motion has taken on the same counterclockwise pattern, the opposite of the long-term average. This may have an effect on the compaction and survival of multiyear ice later this season.

Compared to averages over the 1981 to 2010 period, air temperatures at the 925 level (about 2,500 feet above the surface) are mostly below average over most of the Arctic Ocean, particularly over north central Russia, part of the Kara Sea, northeastern Russia, Alaska, and the Canadian Arctic Archipelago (Figure 2c). Scandinavia has seen record high temperatures this summer; for the first half of July, 925 hPa temperatures in this area were up to 6 degrees Celsius (11 degrees Fahrenheit) above the 1981 to 2010 average, and relatively warm conditions extended into the largely ice-free Barents Sea. The extreme warmth that has plagued the Pacific Northwest has also influenced much of western Canada and has been linked to a string of forest fires in British Columbia.

Comparison to previous years

Figure 3. The graph above shows Arctic sea ice extent as of July 13, 2021, along with daily ice extent data for five 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 red. 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 brisk pace of ice loss for the first half of July was at 124,000 square kilometers (47,900 square miles) per day, exceeding the long-term average of 80,000 square kilometers (30,900 square miles) per day. From June 1 through July 13, the Arctic Ocean lost a total of 1.73 million square kilometers (668,000 square miles) of sea ice. This is roughly equivalent in size to the state of Florida.

Thick ice in the Beaufort Sea

Figure 4a. This map shows the age of Arctic sea ice for the June 25 to July 1 period. Note the lingering multiyear ice north of the Alaskan coast.

Credit: M. Tschudi, W. Meier, and Stewart, NASA NSIDC DAAC
High-resolution image

Figure 4b. This true-color image shows sea ice off the coast of Alaska in the Beaufort Sea, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the NASA Terra satellite on June 26, 2021. The more bluish ice—toward the right side of the image, with the bigger visible floes—is the multiyear ice. The grayish ice, more towards the coast is first-year ice.

Credit: NASA Worldview
High-resolution image

While ice extent is very low for the Arctic Ocean as a whole, with a nearly ice-free Laptev Sea, ice extent in the Beaufort Sea remains extensive and in areas extends to the Alaskan shores. This is explained by the presence of a tongue of fairly thick multiyear ice in the region that is resistant to melting out (Figure 4a). Some of this ice is at least four years old. As shown in a study in press led by R. Mallett and colleagues, winds associated with a period of strong high pressure transported this tongue of ice into the Beaufort Sea this past winter from the central Arctic Ocean and the shores of the Canadian Arctic Archipelago. The image from the NASA Moderate Resolution Imaging Spectroradiometer for June 26, shows the difference between first-year ice close to the shore and the high concentration of multiyear ice farther north (Figure 4b). Whether this thick ice melts away through the remainder of this summer in the fairly warm waters of the Beaufort Sea remains to be seen; if it does, it will reduce the Arctic’s remaining store of multiyear ice.

Further Reading

Serreze, M. C. and A.P. Barrett. 2008. The summer cyclone maximum over the central Arctic Ocean. Journal of Climate, 21, 1048-1065, doi:10.1175/2007JCLI1810.1.

At the end of the first week of July, Arctic sea ice extent was tracking at record low for this time of year. July is the month with most rapid sea ice decline. As in most of the years in the past decade, June saw rapid ice loss in Hudson Bay, Baffin Bay, the Siberian coast, and the Chukchi Sea. However, ice remains extensive north of Alaska.

Overview of conditions

Figure 1. Arctic sea ice extent for June 2021 was 10.71 million square kilometers (4.14 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

Loss of Arctic sea ice in June was relatively steady and rapid. The monthly average extent for June 2021 was 10.71 million square kilometers (4.14 million square miles). This was 300,000 square kilometers (116,000 square miles) above the record low for the month set in 2016 and 1.05 million square kilometers (405,000 square miles) below the 1981 to 2010 average. The average extent for the month ranks sixth lowest in the passive microwave satellite record. Large open-water areas developed in the Laptev and East Siberian Seas, and warm winds pushed the ice edge north in the Kara and Barents Seas near Novaya Zemlya. The Fram Straight region and the area to the north of northeastern Greenland had an unusually low ice concentration as the month drew to a close because of both pre-existing thin ice and unusually warm weather. By contrast, by June’s end, sea ice still persisted along the northern coast of Alaska.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of July 6, 2021, along with daily ice extent data for five 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 red. 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 average sea level pressure in the Arctic in millibars for June 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

Figure 2c. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for June 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

Unusually strong low pressure (up to 10 hPa below average) near the North Pole dominated the average atmospheric circulation pattern for June (Figure 2b). High pressure also hovered over western Europe, driving winds northeastward over the Norwegian Sea and into the Barents and Kara Seas. Temperatures at the 925 hPa level over Scandinavia were high as a result, averaging 2 to 5 degrees Celsius (4 to 9 degrees Fahrenheit) above average (Figure 2c). Above average temperatures were also present over northeastern Siberia along the Laptev and East Siberian Sea coast, but cool conditions prevailed over central Alaska and central Siberia. Most of the Arctic Ocean was 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above average, although a region near the Severnaya Zemlya islands was near average. Air temperatures near strong low pressure areas over the Arctic Ocean have historically been associated with relatively cool conditions. However, June temperatures in the vicinity of the low-pressure pattern were near the long-term average.

June 2021 compared to previous years

Figure 3. Monthly June ice extent for 1979 to 2021 shows a decline of 4.0 percent per decade.

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

The pace of ice loss for the month was faster than average; the Arctic lost a total of 2.39 million square kilometers (923,000 square miles) during the month of June. This corresponds to an average ice loss of 79,600 square kilometers (30,700 square miles) per day compared to the 1981 to 2010 average loss of 56,200 square kilometers (21,700 square miles) per day. Through 2021, the linear rate of decline for June sea ice extent is 4.0 percent per decade. This corresponds to 47,000 square kilometers (18,000 square miles) per year. The cumulative June ice loss over the 43-year satellite record is 1.99 million square kilometers (768,000 square miles), based on the difference in linear trend values in 2021 and 1979. The loss of ice since 1979 in June is equivalent to about three times the size of Texas.

“Last Ice Area” not lasting all that well

Figure 4. This map and graph shows sea ice conditions in the Wandel Sea during the summer of 2020. The top map includes a locator map and a map of sea ice concentration in the northern Greenland area in August 2020 as the RV Polarstern transited the area (marked by the red line). The bottom graph shows sea ice concentration for the area marked by the black outline over the course of the 2020 summer, derived from NSIDC Climate Data Record for sea ice. In most years since 1978, sea ice concentration average is above 90 percent (solid blue line) throughout the summer.

Credit: Schweiger et al. 2021
High-resolution image

The area north of Greenland and the Canadian Archipelago has recently been referred to as the “Last Ice Area” (LIA) because ice has persisted there in late summer decades while in other regions ice largely melts away. In the LIA, ice is the thickest and oldest in the Arctic, and ice circulation tends to keep ice pressed against the northern coasts of these islands. However, in the summer of 2020, the easternmost portion of the LIA, know as the Wandel Sea, had record low sea ice concentration (Figure 4). This provided easy access to the interior Arctic ice pack for the icebreaker RV Polarstern last summer as it returned to complete research associated with the year-long Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition.

A recent paper by colleagues from University of Washington in Seattle, and the University of Toronto Mississauga explains that the record low ice concentration in the Wandel Sea was caused by both thinning of the thick multi-year sea ice and unusual wind-forced ice motion away from the area, particularly in mid- to late August. Changes in the winds replaced the old ice with thinner first-year ice. The authors note that the unusual winds were a significant factor, likely a result of natural variability but that persistent long-term thinning trends in the LIA multi-year sea ice pack were also partly to blame. Winds would not have had as large of an impact in previous decades when the pack was thicker on average.

Antarctic notes

Figure 5. The graph above shows Antarctic sea ice extent as of July 6, 2021, along with daily ice extent data for five 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 red. 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

Sea ice in the Southern Ocean surrounding Antarctica was well above the 1981 to 2010 average extent in June, rising above the ninetieth percentile near the end of the month. Areas north of Dronning Maud Land, Wilkes Land, and the Ross and Amundsen Seas were above average in extent, while regions on either side of the Antarctic Peninsula—the Bellingshausen Sea and the northwestern Weddell Sea—were below average.

The atmospheric circulation pattern for the month was characterized by a strong Amundsen Sea low pressure area (10 to 15 millibars lower than the average for the month) and a weak “wave-3 pattern” around the rest of the Southern Ocean. A wave-3 pattern consists of three high-pressure areas (in this case, the Weddell Sea, Indian Ocean, and southwest Pacific) interspersed with three low-pressure regions (the Amundsen Sea, the areas south of South Africa, and the area south of Australia).

Further reading

Schweiger, A. J., M. Steele, and J. Zhang et al. 2021. Accelerated sea ice loss in the Wandel Sea points to a change in the Arctic’s Last Ice Area. Communications Earth & Environment 2, 122 (2021), doi:10.1038/s43247-021-00197-5.