Storm Damage

The pace of sea ice decline in April was near average, while sea ice extent ranked fourth lowest in the satellite record. Sea ice age mapping shows a slight increase in the amount of older ice, but the Arctic is still dominated by first-year ice, unlike during the 1990s and earlier. An intense March storm, spanning much of the Arctic Ocean, created large ice rubble piles near Utqiaġvik, Alaska, and caused difficulties for Indigenous hunters along the northwestern Alaskan coast.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for April 2020 was 13.73 million square kilometers (5.30 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

Arctic sea ice extent for April averaged 13.73 million square kilometers (5.30 million square miles). Last month, March ranked as the eleventh lowest ice extent in the satellite record, higher than it has been in the last five years. However, the pace of ice retreat increased toward the end of March and the ice extent in April retreated at rates similar to those seen in recent years. Consequently, ice extent for April 2020 ended up as fourth lowest—280,000 square kilometers (108,000 square miles) above the record low set in April 2019, and 960,000 square kilometers (371,000 square miles) below the 1981 to 2010 mean. As of April 30, the daily extent tracked at fourth lowest in the satellite data record.

April sea ice extent primarily retreated in the Sea of Okhotsk and the Bering Sea, but also within the Labrador Sea, Baffin Bay, the Davis Strait, and the southern end of the East Greenland Sea. However, the ice edge remained more extensive than average for this time of year in the Barents Sea between Svalbard and Novaya Zemlya, as well as in the northern East Greenland Sea. Ocean heat transport has been a good predictor of winter sea ice variability in this general region. Over the past five years, ocean temperatures have cooled in this area because of a smaller transport of warm Atlantic water from the North Atlantic. Thus, it is not surprising that the winter ice cover in this region has slowly returned from near-average to slightly above-average conditions.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of April 30,2020, along with daily ice extent data for four previous years and the record low year. 2020 is shown in blue, 2019 in green, 2018 in orange, 2017 in brown, 2016 in purple, 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 2a. The graph above shows Arctic sea ice extent as of May 5,2020, along with daily ice extent data for four previous years and the record low year. 2020 is shown in blue, 2019 in green, 2018 in orange, 2017 in brown, 2016 in purple, 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 the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for April 1 to 30, 2020. 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 Division |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 April 1 to 30, 2020. 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 Division
High-resolution image

The pace of ice loss in April was 33,400 square kilometers  (12,900 square miles) per day. This was dominated by ice loss primarily in the Bering Sea and the Sea of Okhotsk, which had rates of retreat of 3,700 and 16,100 square kilometers per day (1,400 and 6,200 square miles per day), respectively. Overall, Arctic sea ice extent decreased by 1.05 million square kilometers (405,000 square miles) in April.

April air temperatures at the 925 hPa level (approximately 2,500 feet above the surface) were 2 to 5 degrees Celsius (4 to 9 degrees Fahrenheit) above average over most of the Arctic Ocean and the Bering Sea, with the exception of Svalbard and the Barents Sea where air temperatures were near average (Figure 2b). Air temperatures were also up to 6 to 8 degrees Celsius (11 to 14 degrees Fahrenheit) above average in Baffin Bay, and up to 8 degrees Celsius (14 degrees Fahrenheit) above average over Siberia, while Canada continued to experience below-average air temperatures for this time of year. This pattern of air temperatures is a result of above-average sea level pressure over Alaska and Siberia, coupled with lower pressures over the central Arctic Ocean, helping to transport warm air from the south over the Bering Sea as well as into the Kara Sea. The wind pattern also caused offshore ice motion within the Kara Sea, pushing the ice edge in the Bering Sea further north.

While 925 hPa air temperatures were above average for much of the Arctic Ocean, conditions in Utqiaġvik, Alaska, turned colder at the end of the month. On April 29, temperatures in Utqiaġvik reached -28.9 Celsius (-20 Fahrenheit), a record low for the date, according to Rick Thoman of the International Arctic Research Center in Fairbanks. It was also the latest date in the season for a temperature of -28.9 degrees Celsius (-20 degrees Fahrenheit) or lower. See below for more on unusual weather and ice events over the past couple of months in the Utqiaġvik region of Alaska.

April 2020 compared to previous years

Figure 3. Monthly XXXXX ice extent for 1979 to 20XX shows a decline of X.X percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly April ice extent for 1979 to 2020 shows a decline of 2.65 percent per decade.

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

Through 2020, the linear rate of decline for April extent is 2.65 percent per decade (Figure 3). This corresponds to a trend of 38,900 square kilometers (15,000 square miles) per year.

The MOSAiC expedition continues during the pandemic

Figure 4. This figure shows the position of the Alfred Wegener Institute RV Polarstern while it is part of the MOSAiC Drift Experiment. |High-resolution image

Figure 4. This figure shows the position of RV Polarstern while it is part of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition. This position is as of April 26, 2020.
High-resolution image

Planning a year-long Arctic Ocean expedition is logistically difficult. Challenges range from finding a suitable ice floe to support the various science activities, to dealing with break up events and having to move instruments to keep them from falling into the Arctic Ocean, to extreme weather conditions. There can also be unexpected visits by polar bears and foxes. Yet, no amount of planning could have prepared the expedition for the coronavirus disease 2019 (COVID-19) pandemic. While the leg-three participants of the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition should have been home by now, the rotation of personnel via aircraft had to be cancelled. Instead, the next exchange of personnel will be at the end of May, relying on two German research vessels, RV Sonne and RV Maria S. Merian, to meet RV Polarstern at the ice edge. The Polarstern will meet the vessels near Svalbard, and after refueling and transferring the freight and people, will head back into the ice to continue the measurement program. Some equipment may be left on the ice floe while the Polarstern is away, the intent being to continue recording data.

Colleagues at the Alfred Wegener Institute (AWI) determined the origin of the ice floe selected to host most of the MOSAiC instrumentation. Satellite observations and ice drift mapping indicates that the floe formed in a polynya north of the New Siberian Islands in early December 2018. At the time the MOSAiC Central Observatory (CO) was established, the ice thickness ranged from 30 to 80 centimeters (12 to 31 inches), which is relatively thin compared to historical ice conditions. Yet recent EM-Bird sea ice thickness sensor observations from helicopter on April 10 show that the CO and the surrounding ice now have a modal thickness of around 1.8 meters (5.9 feet). Leaving valuable scientific gear on the floe is risky given the possibility that the floe will break up or be crushed while the Polarstern is away. Indeed, new leads (roughly linear openings in the ice cover) formed on April 10, and on April 27, compressive forces on the ice led to ridging. Such events raise concern that instruments may be lost or damaged while the Polarstern is away. Furthermore, during the 2019 to 2020 winter, there was a strong transpolar drift of the ice, which may require a relocation of the camp further north so that the study site does not drift out of the Arctic Ocean before the end of September. This strong ice drift appears to be related to last winter’s strongly positive phase of the Arctic Oscillation.

Impacts of a major storm on Alaska Arctic sea ice

Figure 5a. This figure shows record low atmospheric mean sea-level pressure (MSLP; lowest for time period 1948 to 2020 on days indicated in graphic) north of Alaska in March 2020 during passage of major storm systems. ||Credit: Tom Ballinger, International Arctic Research Center, University of Alaska Fairbanks. |High-resolution image

Figure 5a. This figure shows record low atmospheric mean sea-level pressure (MSLP; lowest for time period 1948 to 2020 on days indicated in graphic) north of Alaska in March 2020 during passage of major storm systems. The figure shows the daily average over the Beaufort and Chukchi Seas (shaded region in inset), which was 992.2 hPa, rather than the minimum of the center of the low, which was 970 hPa. 

Credit: Tom Ballinger, International Arctic Research Center, University of Alaska Fairbanks.
High-resolution image

Figure 5b: This photo shows a pressure ridge formed in shorefast sea ice near Utqiaġvik, Alaska, as a result of storm-driven ice deformation. ||Credit: Billy Adams of Utqiaġvik, Alaska. |High-resolution image

Figure 5b: This photo shows a pressure ridge formed in shorefast sea ice near Utqiaġvik, Alaska, as a result of storm-driven ice deformation.

Credit: Billy Adams of Utqiaġvik, Alaska.
High-resolution image

From March 19 to 21, a record low pressure system (Figure 5a) moved across the Chukchi and Beaufort Seas, with central pressure minimums reaching 970 hPa. Our colleague Hajo Eicken, Professor of Geophysics at the University of Alaska-Fairbanks, notes that the passage of this record low highlights the importance of major storm events in shaping the sea ice cover. A series of storms in March 2020, with peak wind speeds exceeding 97 kilometers per hour (60 miles per hour), piled up ice along the eastern Chukchi Sea coastline. Large ice pressure ridges (Figure 5b) can ground on the seafloor and help anchor the shorefast ice. They create a more stable ice platform for use by the local community to gain access to marine mammals that have been located further offshore. In recent years, milder ice conditions have resulted in less stable coastal ice. Ice deformation events due to major storms such as those that occurred this March can help make up for reduced ice growth from higher temperatures. Billy Adams, an Iñupiaq ice expert from Utqiaġvik, Alaska, reports that thicker and stronger first-year ice this winter resulted in grounding of pressure ridges further offshore than in prior recent years (Figure 5b). Community ice trails also have to extend further out from shore.

Whereas the storms piled up ice against the eastern Chukchi Sea shoreline, prevailing wind directions in the Beaufort Sea created open water and broke up large stretches of the ice pack into small floes. Break up and deformation of ice floes during passage of these storm systems threatened to disrupt a field experiment on an ice floe in the Beaufort Sea. The changing sea ice regime increasingly challenges on-ice operations and ice-based scientific research in this part of the Arctic. The absence of a strong Beaufort high pressure system in 2020 and previous years (Moore et al., 2018) has resulted in more sluggish ice movement in the Beaufort Sea. While this helps build up a thicker ice pack and makes it easier for scientific ice camps to operate in the region, it also allows for major storm systems to penetrate, wreaking havoc on the ice cover and bringing snowfall and blizzard conditions.

Update on sea ice age

Figure 6. The top maps compare Arctic sea ice age for (a) March 12 to 18, 1985, and (b) March 11 to 17, 2020. The time series (c) of mid-March sea ice age as a percentage of Arctic Ocean coverage from 1985 to 2020 shows the nearly complete loss of 4+ year old ice; note the that age time series is for ice within the Arctic Ocean and does not include peripheral regions where only first-year (0- to 1-year-old) ice occurs, such as the Bering Sea, Baffin Bay, Hudson Bay, and the Sea of Okhotsk||Credit: W. Meier, NSIDC|High-resolution image

Figure 6. The top maps compare Arctic sea ice age for (a) March 12 to 18, 1985, and (b) March 11 to 17, 2020. The time series (c) of mid-March sea ice age as a percentage of Arctic Ocean coverage from 1985 to 2020 shows the nearly complete loss of 4+ year old ice; note the that age time series is for ice within the Arctic Ocean and does not include peripheral regions where only first-year (0- to 1-year-old) ice occurs, such as the Bering Sea, Baffin Bay, Hudson Bay, and the Sea of Okhotsk

Credit: W. Meier, NSIDC
High-resolution image

After the winter maximum extent, it is useful to check in on sea ice age. Older ice is generally thicker and thus less prone to melt completely during the following summer. As noted in previous years, the ice has been on average getting younger, with very little old (4+ year) ice remaining in the Arctic. During the 1980s, a substantial portion of the Arctic Ocean was covered by this old ice around the sea ice maximum (Figure 6). Last year, however, was a record low extent of 4+ year ice for this time. During the week of March 11 to 17, 326,000 square kilometers (126,000 square miles) or 4.3 percent of the ice within the Arctic Ocean was at least four years old. This is up from last year when only 91,000 square kilometers (35,000 square miles) or 1.2 percent of this old ice remained. Thus, there has been some replenishment of the oldest, thickest ice over the past year. However, the amount is still far below mid-1980 levels when over 2 million square kilometers (772,000 square miles) or around 35 percent of the Arctic Ocean was comprised of 4+-year-old ice.

The increase in the oldest ice has been offset by younger categories, one to four years old. The amount of first-year ice (0- to 1-year old) is close to the same level as last year’s, at about 70 percent of the Arctic Ocean ice cover, much higher than during the mid-1980s, when only 35 to 40 percent of the ice was less than a year old. A study of the updated ice age (and ice motion) product is being published in The Cryosphere (Tschudi et al., 2020).

Fast drifting trace elements

Figure 7. This figure shows ice motion from March 25 to March 31, 2020, revealing a strong Transpolar Drift and ice export towards Svalbard and out of Fram Strait.||Credit: NSIDC| |High-resolution image

Figure 7. This figure shows ice motion from March 25 to March 31, 2020, revealing a strong Transpolar Drift and ice export towards Svalbard and out of Fram Strait.

Credit: NSIDC
High-resolution image

The Transpolar Drift Stream, a general motion of ice from shores of Siberia, across the Pole and then towards Fram Strait, was enhanced during the extreme positive phase of the Arctic Oscillation this winter. A new study found that freshwater runoff from rivers around the western Arctic Ocean (Siberia, Alaska, and northwestern Canada) brings significant amounts of trace elements into the Arctic Ocean through the Transpolar Drift Stream. Trace elements entering the Arctic Ocean from rivers are chemically bound with organic matter in the rivers, which allows them to be transported long distances. The Transport Drift Stream can then take those trace elements across the Arctic Ocean and towards Fram Strait. This may have important implications for marine ecosystems. One key element, iron, is a key nutrient for primary productivity (e.g., algae growth). More iron transported into the Arctic Ocean and more sunlight from reduced sea ice extent can enhance productivity. As permafrost thaws and more nutrients are released, this could become an important component of change in marine ecosystems in the future.

Antarctica sea ice near average

Figure 2a. The graph above shows Antarctic sea ice extent as of May 5, 2020, along with daily ice extent data for four previous years and the record high year. 2020 is shown in blue, 2019 in green, 2018 in orange, 2017 in brown, 2016 in purple, 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

Figure 8a. The graph above shows Antarctic sea ice extent as of May 5, 2020, along with daily ice extent data for four previous years and the record high year. 2020 is shown in blue, 2019 in green, 2018 in orange, 2017 in brown, 2016 in purple, 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

Figure 8b. This figure shows Antarctic regional extent over the last 12 monthsAntarctic regional extent over the last 12 months—May 1, 2019, through April 30, 2020. Regions are noted in the map inset (“Bell.-Amund. Seas” refers to the Bellingshausen and Amundsen Seas). ||Credit: National Snow and Ice Data Center|High-resolution image

Figure 8b. This figure shows Antarctic regional extent over the last 12 months. Antarctic regional extent over the last 12 months—May 1, 2019, through April 30, 2020. Regions are noted in the map inset (“Bell.-Amund. Seas” refers to the Bellingshausen and Amundsen Seas).

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

Antarctic sea ice extent tracked close to the median line from mid-March until the first week of April when the rate of growth fell below the median rate and the trend returned to the lower end of the observed 41-year range. However, it remained within the interdecile range. Sea ice extent is near average in most sectors, but is slightly below average in the Ross Sea, parts of the Weddell Sea, and off the coast of Dronning Maud Land.

NSIDC has recently published regional ice extent and concentration spreadsheets for five sectors of the Southern Ocean surrounding Antarctica. These allow users to quickly examine how sea ice is varying in different regions. This is similar to the regional spreadsheets previously available for the Arctic.

The regional spreadsheets are illustrative of how the seasonal cycle varies in different parts of the Antarctic. For example, as shown for the past year, the seasonal variation is dominated by the changes in the Weddell Sea, going from a maximum of around 7 million square kilometers (2.70 million square miles) in late August to just over 1 million square kilometers (386,000 square miles), with a very sharp decline during December 2019. Significant seasonal ice retreat starts first in the Indian Ocean region in late September, with a very short transition between advance and retreat. Other regions show less seasonal variability. Notably, the dates of the maximums of the regions varies over a couple months, but all reach a minimum at nearly the same time—end of February to early March.

Future reading:

Årthun, M., T. Eldevik, and L. H. Smedsrud. 2019. The Role of Atlantic Heat Transport in Future Arctic Winter Sea Ice Loss. Journal of Climate. doi:10.1175/JCLI-D-18-0750.1.

Charette, M. A., L. E. Kipp, L. T. Jensen, J. S. Dabrowski, L. M. Whitmore, J. N. Fitzsimmons, et al. 2020. The Transpolar Drift as a Source of Riverine and Shelf‐Derived Trace Elements to the Central Arctic Ocean. Journal of Geophysical Research: Oceansdoi:10.1029/2019JC015920

Krumpen, T., et al. 2020. The MOSAiC ice floe: sediment-laden survivor from the Siberian shelf. The Cryosphere. doi:10.5194/tc-2020-64.

Moore, G. W. K., A. Schweiger, J. Zhang, and M. Steele. 2018. Collapse of the 2017 winter Beaufort High: A response to thinning sea ice? Geophysical Research Letters. doi:10.1002/2017GL076446

Tschudi, M. A., W. N. Meier, and J. S. Stewart. 2020. An enhancement to sea ice motion and age products at the National Snow and Ice Data Center. The Cryospheredoi.10.5194/tc-14-1519-2020.

 

A positively persistent, persistently positive Arctic Oscillation

Sea ice extent for February 2020 tracked below average, ranking as the thirteenth lowest monthly average in the satellite record. A brief pause in ice growth in the middle of February was related to the regional wind pattern. As has been the case for the past several months, the Arctic Oscillation was in a persistently positive phase. This manifested as unusually low sea level pressure over the Atlantic side of the Arctic Ocean and high pressure over Eastern Eurasia, extending eastward into Arctic Canada.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for February 2020 was 14.68 million square kilometers (5.67 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

Arctic sea ice extent for February 2020 was 14.68 million square kilometers (5.67 million square miles), the thirteenth lowest in the satellite record. This was 620,000 square kilometers (239,000 square miles) below the 1981 to 2010 February average and 710,000 square kilometers (274,000 square miles) above the record low mark for February set in 2018. At the end of February, ice extent was below average over parts of the Barents and Kara Seas, and the eastern Greenland Sea.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of March 2, 2020, along with daily ice extent data for four previous years and the record low year. 2019 to 2020 is shown in blue, 2018 to 2019 in green, 2017 to 2018 in orange, 2016 to 2017 in brown, 2015 to 2016 in purple, and 2011 to 2012 in dotted 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 2a. The graph above shows Arctic sea ice extent as of March 3, 2020, along with daily ice extent data for four previous years and the record low year. 2019 to 2020 is shown in blue, 2018 to 2019 in green, 2017 to 2018 in orange, 2016 to 2017 in brown, 2015 to 2016 in purple, and 2011 to 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

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

Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for February 2020. 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 Division High-resolution image|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 February 2020. 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 Division
High-resolution image

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars (hPa) for February 2020. Yellows and reds indicate high air pressure; blues and purples indicate low pressure. ||Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division High-resolution image|High-resolution image

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars (hPa) for February 2020. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

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

Figure2d. Over the past several months, the Arctic Oscillation has been in a persistently positive phase. This manifested as unusually low sea level pressure over the Atlantic side of the Arctic Ocean and high pressure over Eastern Eurasia, extending eastward into Arctic Canada. This figure shows the Observed Arctic Oscillation Index from November 2019 through March 1, 2020. Credit: National Weather Service Climate Prediction Center|High-resolution image

Figure 2d. Over the past several months, the Arctic Oscillation has been in a persistently positive phase. This manifested as unusually low sea level pressure over the Atlantic side of the Arctic Ocean and high pressure over Eastern Eurasia, extending eastward into Arctic Canada. This figure shows the Observed Arctic Oscillation Index from November 2019 through March 1, 2020. Credit: National Weather Service Climate Prediction Center
High-resolution image

Through the month, sea ice grew by an average of 22,100 square kilometers (8,500 square miles) per day, fairly close to the average rate over the 1981 to 2010 period of 20,200 square kilometers (7,800 square miles) per day.

Air temperatures at the 925 hPa level (about 2,500 feet above the surface, Figure 2b) were from 1 to 7 degrees Celsius (2 to 13 degrees Fahrenheit) above average across much of the Eurasian side of the Arctic Ocean, with especially large departures from average around the Taymyr Peninsula (Figure 2b). At the same time, northern Alaska and the Chukchi and Beaufort Seas saw temperatures by up to 6 degrees Celsius (11 degrees Fahrenheit) below average.

The sea level pressure pattern average for February was similar to that of January, with low pressure areas extending from the northern North Atlantic into the Kara Sea, paired with high pressure over eastern Eurasia and extending across Alaska and into northern Canada (Figure 2c). Pressures over the Barents and Kara Seas were as much as 18 hPa below the 1981 to 2010 average. This pattern was associated with a positive phase of the Arctic Oscillation (AO), continuing the basic AO pattern that has persisted since December. A very high positive AO index (4 to 6) marked portions of February, which has been associated with warm air and stormy weather from Northern Europe into the Barents Sea. This likely explains the reduction in sea ice extent in the Barents Sea and the week-long pause in sea ice growth for the Arctic as a whole during the middle of the month. Beginning around February 22, total Arctic sea ice extent started to increase again, driven by substantial increases in sea ice extent in the Bering Sea, and modest ice growth in the Barents Sea.

Previous studies, led by University of Washington scientist Ignatius Rigor (e.g., Rigor et al., 2002), suggest that a positive winter phase of the Arctic Oscillation favors low sea ice extent the subsequent September. Wind patterns “flush” old, thick ice out of the Arctic Ocean through the Fram Strait and promote the production of thin ice along the Eurasian coast that is especially prone to melting out in summer. However, in recent years, this relationship has not been as clear (Stroeve et al., 2011). The potential effects this winter’s positive AO on the summer evolution of ice extent and the September 2020 minimum bears watching.

The Bering Sea ice extent is near-average, which is in marked contrast to the previous two years when extent was at or near record lows for the satellite record through much of the winter (Thoman et al., 2020).

February 2020 compared to previous years

Figure 3. Monthly February sea ice extent for 1979 to 2020 shows a decline of 2.91 percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly February sea ice extent for 1979 to 2020 shows a decline of 2.91 percent per decade.

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

Including 2020, the linear rate of decline for February ice extent is 2.91 percent per decade. This corresponds to a trend of 44,500 square kilometers (17,200 square miles) per year, which is roughly twice the size of the state of New Hampshire. Over the 42-year satellite record, the Arctic has lost about 1.75 million square kilometers (676,000 square miles) of sea ice in February, based on the difference in linear trend values in 2020 and 1979. This is comparable to the size of the state of Alaska.

Nearing the minimum in the south

Figure 4. Antarctic sea ice extent likely reached its annual minimum on February 20 and 21, 2020. Antarctic sea ice extent for February 20 and 21, 2020 was 2.69 million square kilometers (1.04 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 4. Antarctic sea ice extent likely reached its annual minimum on February 20 and 21, 2020. Antarctic sea ice extent for February 20 and 21, 2020 was 2.69 million square kilometers (1.04 million square miles). The orange line shows the 1981 to 2010 average extent for February 21. Sea Ice Index data. About the data

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

As of February 20 and 21, Antarctic sea ice extent likely reached its annual minimum at 2.69 million square kilometers (1.04 million square miles). However, as of March 1, sea ice extent has increased only marginally above the minimum value, to 2.71 million square kilometers (1.05 million square miles). The latest Antarctic minimum over the satellite record was March 3. We anticipate that sea ice will continue to expand as late summer and autumn proceed.

At this time of year, Antarctic sea ice cover is characterized by a number of small remnant patches of ice around the coast, with the largest being the western Weddell Sea and the Amundsen-Ross Sea coastal area. Overall sea ice remains below the 1981 to 2010 average, a trend that has persisted since September 2016. Sea ice extent in the Weddell area is near average overall, while ice extent in the Amundsen-Ross region is well below average. However, a patch of sea ice in the Pine Island Bay region is hampering research vessels in the area seeking to study ice-ocean interaction near some of the very large and rapidly changing glaciers draining the West Antarctic Ice Sheet.

The increasing influence of ocean waves on sea ice

A new project from University of Washington’s Applied Physics Laboratory is focusing on the complex ways that ocean waves and sea ice are interacting, as reported in a recent ARCUS webinar by researcher Jim Thomson. In October 2019, a storm-generated swell of 3- to 4-meter (10- to 13-foot) waves was observed in the Chukchi Sea. These waves are significantly larger than any previously observed in the region and are linked to declining autumn sea ice cover. Waves and sea ice have a complex range of interactions (Squire, 2018). Sea ice acts as a barrier between the ocean and atmosphere, limiting the influence of winds on the ocean surface. Waves encountering an open pack are strongly damped by the interaction of ice floes bumping together. However, large waves can fracture the ice pack and set landfast ice in motion, further breaking up the ice pack and eventually reducing the damping effect. In some cases in Antarctica, the loss of sea ice damping of waves may trigger ice shelf collapse if the ice shelves have been pre-conditioned and weakened (Massom et al., 2018). When ice is forming, waves can push pancakes of ice together, aiding in ice formation. The Coastal Ocean Dynamics in the Arctic (CODA) and Stratified Ocean Dynamics of the Arctic (SODA) projects are dedicated to further understanding these complex interactions.

Introducing the Sea Ice Analysis Tool

Figure 6. NSIDC developed the Sea Ice Analysis Tool to allow users to interactively analyze sea ice data from the Sea Ice Index while allowing them to visualize the data using different reference and average periods. ||Credit: National Snow and Ice Data Center| High-resolution image

Figure 5. NSIDC developed the Sea Ice Analysis Tool to allow users to interactively analyze sea ice data from the Sea Ice Index while allowing them to visualize the data using different reference and average periods.

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

NSIDC has developed a new visualization tool—the Sea Ice Analysis Tool—that helps users customize sea ice extent and concentration data more easily than ever before. Users have the capability to create graphs or maps that show changes in sea ice based on their chosen criteria.

Drawing on input from the user community, the Arctic Sea Ice News & Analysis (ASINA) team developed the Sea Ice Analysis Tool as a way to allow users to interactively analyze sea ice data from the Sea Ice Index while allowing them to visualize the data using different reference and average periods. This is a change from other ASINA tools, such as ChArctic, that do not have this same flexibility because they use static averaging periods.

This new tool allows users to analyze monthly-averaged or daily sea ice extent and concentration via interactive maps and graphs. In addition, the user can plot monthly ice extent anomalies, map sea ice concentration anomalies, and display images of trends in sea ice concentration, with anomalies being departures from the long-term average.

All maps and graphs are customizable; they can be created for a variety of dates, averaging periods, and trends. In addition, maps can be zoomed to focus on a specific region.

Further reading

Gautier, A. 2020. Seeing sea ice: A new tool shows dynamic changes. NSIDC.org.

Massom, R. A., T. A. Scambos, L. G. Bennetts, P. Reid, V. A. Squire, and S. E. Stammerjohn. 2018. Antarctic ice shelf disintegration triggered by sea ice loss and ocean swell. Nature. doi.org/10.1038/s41586-018-0212-1.

Rigor, I. G., J. M. Wallace, and R. L. Colony. 2002. Response of Sea Ice to the Arctic Oscillation. Journal of Climate. doi.org/10.1175/1520-0442(2002)015<2648:ROSITT>2.0.CO;2.

Squire, V. A fresh look at how ocean waves and sea ice interact. 2018. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. doi.org.colorado.idm.oclc.org/10.1098/rsta.2017.0342.

Stroeve, J. C., J. Maslanik, M. C. Serreze, I. Rigor,  W. Meier, and C. Fowler. 2011. Sea ice response to an extreme negative phase of the Arctic Oscillation during winter 2009/2010, Geophyical Research Letters. doi:10.1029/2010GL045662.

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

Thomson, J., Y. Fan, S. Stammerjohn, J. Stopa, W. E. Rogers, F. Girard-Ardhuin, F. Ardhuin, H. Shen, W. Perrie, H. Shen, S. Ackley, A. Babanin, Q. Liu, P. Guest, T. Maksym, P. Wadhams, C. Fairall, O. Persson, M. Doble, H. Graber, B. Lundr, V. Squires, J. Gemmricht, S. Lehneru, B. Holt, M. Meylan, J. Brozenax, and J. R. Bidlot. 2016. Emerging trends in the sea state of the Beaufort and Chukchi seas. Ocean Modelling. doi.org/10.1016/j.ocemod.2016.02.009.

A mostly ho-hum January

Sea ice extent for January 2020 tracked well below average, with the monthly average tied at eighth lowest in the satellite record. While air temperatures were above average across much of the Arctic Ocean, it was colder than average over the northern Barents Sea, Alaska, the eastern Canadian Arctic Archipelago, and Greenland.

Overview of conditions

Figure 1. Arctic sea ice extent for January 2020 was 13.65 million square kilometers (5.27 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 1. Arctic sea ice extent for January 2020 was 13.65 million square kilometers (5.27 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

Arctic sea ice extent for January 2020 was 13.65 million square kilometers (5.27 million square miles), placing it eighth lowest in the satellite record along with 2014. This was 770,000 square kilometers (297,000 square miles) below the 1981 to 2010 January average and 570,000 square kilometers (220,000 square miles) above the record low mark for January set in 2018. At the end of January, ice extent was below average over parts of the Bering Sea, the Sea of Okhotsk, and the East Greenland Sea. The near average extent in the Barents Sea contrasts with recent years, which were characterized by well below average extent in this area.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of XXXX X, 20XX, along with daily ice extent data for four previous years and the record low year. 2018 to 2019 is shown in blue, 2017 to 2018 in green, 2016 to 2017 in orange, 2015 to 2016 in brown, 2014 to 2015 in purple, and 2011 to 2012 in dotted 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 2a. The graph above shows Arctic sea ice extent as of February 3, 2020, along with daily ice extent data for four previous years and the record low year. 2019 to 2020 is shown in blue, 2018 to 2019 in green, 2017 to 2018 in orange, 2016 to 2017 in brown, 2015 to 2016 in purple, and 2012 to 2013 in dotted 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 March 2019. 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 Division|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 2020. 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 Division
High-resolution image

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars (hPa) from January 1, 2020 to January 31, 2020. Yellows and reds indicate high air pressure; blues and purples indicate low pressure. ||Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division|High-resolution image

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars (hPa) from January 1, 2020 to January 31, 2020. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

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

Through the month, sea ice grew by an average of 45,200 square kilometers (17,500 square miles) per day, fairly close to the average rate over the 1981 to 2010 period of 42,700 square kilometers (16,500 square miles per day). This contrasts with December, when the growth rate was considerably faster than average.

Air temperatures at the 925 hPa level (about 2,500 feet above the surface) were from 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) above average across much of the Arctic Ocean, but temperatures were up to 5 to 6 degrees Celsius (9 to 11 degrees Fahrenheit) below average over the northern Barents Sea and southern Alaska (Figure 2b). Temperatures were also below average over much of the eastern Canadian Arctic Archipelago and Greenland.

The sea level pressure pattern average for the month was somewhat unusual, with low pressure extending from the northern North Atlantic into the Kara Sea, contrasting with high pressure over eastern Eurasia and extending across Alaska and northern Canada (Figure 2c). Pressures over the Kara Sea region were as much as 15 hPa below the 1981 to 2010 average. This pattern was associated with a strongly positive phase of the Arctic Oscillation through most of the month. However, toward the end of January, the Arctic Oscillation Index had returned to near neutral conditions.

January 2020 compared to previous years

Figure 3. Monthly XXXXX ice extent for 1979 to 201X shows a decline of X.X percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly January ice extent for 1979 to 2020 shows a decline of 3.15 percent per decade.

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

Including 2020, the linear rate of decline for January ice extent is 3.15 percent per decade. This corresponds to a trend of 45,400 square kilometers (17,500 square miles) per year, which is roughly twice the size of the state of New Hampshire. Over the 42-year satellite record, the Arctic has lost about 1.86 million square kilometers (718,000 square miles) of ice in January, based on the difference in linear trend values in 2020 and 1979. This is an area larger than the state of Alaska.

Check-in on Antarctic sea ice

Figure 4. Antarctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 4. Antarctic sea ice extent for January 2020 was 4.51 million square kilometers (1.74 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

In the Antarctic, the rate of ice loss slowed considerably over the month of January. During the month, extent declined 3.19 million square kilometers (1.23 million square miles), which is slower than the 1981 to 2010 average loss of 3.79 million square kilometers (1.46 million square miles). By the end of the month, extent was nearly within the interquartile range of the median extent, though still below average. January is the month of the second largest seasonal ice loss, behind December, as the Antarctic extent approaches its annual minimum, usually in February. Extent was lower than average in the eastern and southeastern part of the Weddell Sea, where cooler conditions prevailed (1 to 2 degrees Celsius, or 2 to 4 degrees Fahrenheit, below average) and higher than average in the northern Weddell. In the eastern Ross Sea, ice cover was dispersed and lower than average despite fairly cool conditions there. Elsewhere around Antarctica, extent was near average, with the ice retreating back to near the coast. The northern Peninsula and much of the Wilkes Land sector of the Southern Ocean was 1 to 2 degrees Celsius (2 to 4 degrees Fahrenheit) above average .

New study implicates ozone-destroying substances in Arctic warming

A new study from Columbia University presents evidence that half of the Arctic sea ice loss and surface warming over the 1955 to 2005 period can be attributed to the greenhouse effect of ozone-depleting substances (ODS). This includes, for example, chlorofluorocarbons—better known as CFCs. ODS concentrations peaked towards the end of the last century, well after the Montreal Protocol of 1987, which called for an end to their production. While the continuing decline of ODS concentrations should lead to healing of the well-known Antarctic Ozone Hole, the fact that that these ODS are also potent greenhouse gases implies that their continued decline in the atmosphere will help to reduce the rate of Arctic warming.

Further Reading:

Polvani, L. M., M. Previdi, M. R. England, G. Chiodo and K. L. Smith. 2020. Substantial twentieth-century Arctic warming caused by ozone-depleting substance. Nature Climate Change. doi:10.1038/s41558-019-0677-4.

Erratum

A reader alerted us that we mistakenly said January 2020 was had the ninth lowest monthly average for sea ice extent. On February 7, we corrected this to say it was tied for eighth lowest.

That’s a wrap: A look back at 2019 and the past decade

The year 2019 saw an early melt onset and high sea surface temperatures during summer in the Beaufort and Chukchi Seas. The September minimum extent ended up tied with 2007 and 2016 for second lowest in the satellite record. Autumn freeze up was slow. In December, the Chukchi Sea finally completely refroze, Hudson Bay iced over, and sea ice extended south into the Bering Sea. The year 2019 still ended up with low extent in the Bering Sea. Taking a longer view, the defining feature of the decade of the 2010s was consistently low Arctic sea ice extent compared to long-term averages.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for December 2019 was 11.95 million square kilometers (4.61 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

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

At the close of December, sea ice growth had gained enough ground for daily extent to rank only seventh lowest, the highest at this time since 2014. Extent averaged for the month was 11.95 million square kilometers (4.61 million square miles), tied with 2006 as the fifth lowest December extent in the satellite record. This was 890,000 square kilometers (344,000 square miles) below the 1981 to 2010 December average and 490,000 square kilometers (189,000 square miles) above the record low mark for December set in 2016.

Total ice extent is less variable this time of year as compared to summer. The reason is that over most longitudes, ice extends to the coast and, thus, cannot grow southward. The only place where extent varies is where the southern limit of ice is not bound by land—the Bering Sea, Sea of Okhotsk, East Greenland Sea, Barents Sea, and Baffin Bay. Other than the East Greenland Sea, which is essentially at average levels, these other regions have slightly below average extents. The Chukchi Sea finally froze up completely on December 24. Only 2016 and 2017 saw open water in the Chukchi later in the season.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of January 5, 2020, along with daily ice extent data for four previous years and the record low year. 2019 to 2020 is shown in blue, 2018 to 2019 in green, 2017 to 2018 in orange, 2016 to 2017 in brown, 2015 to 2016 in purple, and 2012 to 2013 in dotted 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 2a. The graph above shows Arctic sea ice extent as of January 6, 2020, along with daily ice extent data for four previous years and the record low year. 2019 to 2020 is shown in blue, 2018 to 2019 in green, 2017 to 2018 in orange, 2016 to 2017 in brown, 2015 to 2016 in purple, and 2012 to 2013 in dotted brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

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

Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for December 2019. 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 Division |High-resolution image

Figure 2b. This plot shows the departure from average air temperature in the Arctic at the 925 hPa level, in degrees Celsius, for December 2019. 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 Division
High-resolution image

December 2019 sea ice grew by an average of 82,100 square kilometers (31,700 square miles) per day. This is faster than the 1981 to 2010 average gain of 64,100 square kilometers (24,700 square miles per day) and is the third fastest December ice growth rate in the satellite record, behind 2006 and 2016. Such fast growth is not surprising. There was considerable ocean heat, particularly in the Chukchi Sea, which delayed freeze up. When the Chukchi waters finally lost their heat, the Arctic was in 24-hour darkness and the cold atmosphere allowed ice to grow rapidly.

Temperatures at the 925 mb level (about 2,500 feet above sea level) were above average over most of the Arctic Ocean. As expected due to continued open water during much of the month, the Chukchi Sea was particularly warm, up to 5 degrees Celsius (9 degrees Fahrenheit) above average (Figure 2b). However, temperatures north of Greenland were also 5 degrees Celsius (9 degrees Fahrenheit) above average. This may be related to strong low pressure over Scandinavia combined with higher than average pressure over the central Arctic Ocean, acting to funnel in warm air from the south.

December 2019 compared to previous years

Figure 3. Monthly December ice extent for 1979 to 2019 shows a decline of X.X percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly December ice extent for 1979 to 2019 shows a decline of 3.6 percent per decade.

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

Including 2019, the linear rate of decline for December ice extent is 3.6 percent per decade. This corresponds to a trend of 46,500 square kilometers (18,000 square miles) per year, which is roughly twice the size of the state of New Jersey. Over the 41-year satellite record, the Arctic has lost about 1.9 million square kilometers (734,000 square miles) of ice in December, based on the difference in linear trend values in 2019 and 1979. This is comparable to the size of Alaska and California combined.

The Arctic Report Card and a view from the north

Figure 4. The Polarstern, frozen into the sea ice in the dark Arctic night during the MOSAiC expedition. ||Photo credit: Alfred-Wegener-Institut/Esther Horvath (CC-BY 4), from http://ciresblogs.colorado.edu/mosaic/2019/12/03/creating-a-mountain/.| High-resolution image

Figure 4. This photo shows the RV Polarstern, the German icebreaker that is frozen into Arctic sea ice during the Multidisciplinary drifting Observatory for the Study of Arctic Change expedition.

Photo credit: Alfred-Wegener-Institut/Esther Horvath
High-resolution image

On December 10, the National Oceanic and Atmospheric Administration (NOAA) 2019 Arctic Report Card was released at the American Geophysical Union Fall Meeting in San Francisco. The report focuses on conditions over the past year in the Arctic. One of the primary topics presented was the impact of low sea ice extent and other changes in the Arctic on Indigenous Peoples, who for the first time contributed directly to the report.

In mid-December, NSIDC senior research scientist and ASINA-contributor Julienne Stroeve joined the second leg of the Multidisciplinary drifting Observatory for the Study of Arctic Change (MOSAiC) expedition. She is now aboard the RV Polarstern, a German icebreaker that is frozen into sea ice north of Siberia, and she will stay on the ship through mid-February. The ship will remain locked in sea ice for a year, hosting several hundred scientists studying the ice, the atmosphere, and the ocean and its biogeochemistry as it drifts across the Arctic Ocean toward Greenland. Stroeve reports that as of January 4, 2020, the ship is located at 87 degrees N and 115 degrees E, about 335 kilometers (208 miles) from the pole. Air temperatures have ranged between -25 to -35 degrees Celsius (-13 to -31 degrees Fahrenheit), with a wind chill of -55 degrees Celsius (-67 degrees Fahrenheit) at times. The ship has been enveloped in complete darkness since mid-October, and the sun will not rise above the horizon until mid-March.

Stroeve is part of the “Remote Sensing City” group, a team that is using passive and active microwave instruments to study the sea ice and to gather improved information on sea ice thickness and snow depth. The extreme conditions of the far north have offered unique challenges to the scientists, including the arrival of a major storm that opened up a lead directly under their research site. The storm endangered the group’s equipment, though they were luckily able to move their instruments to safer ice. The instruments are currently situated on multiyear ice but the group is considering moving them to first-year ice to obtain data on salinated ice and snow. Moving the instruments and cables to a new site would require a major effort from the group, but gathering data from first-year ice would be valuable.

The expedition can be followed via the MOSAiC website as well as through a blog written by our Cooperative Institute for Research in Environmental Sciences (CIRES) colleague, Matthew Shupe, who is an atmospheric scientist and a co-coordinator of the MOSAiC project.

The southern view

Figure 5. Antarctic sea ice extent for December 2019 was 9.30 million square kilometers (3.59 million square miles). The orange 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 5. Antarctic sea ice extent for December 2019 was 9.30 million square kilometers (3.59 million square miles). The orange 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

In the Southern Hemisphere, the summer ice loss rate slowed somewhat during the month. Daily sea ice extent remains below average, but is well above the record low levels seen in 2018. The December monthly average extent was 9.30 million square kilometers (3.59 million square miles). This is the fifth lowest December extent in the satellite record, above the record low mark set in 2016 as well as 2018, 1982, and 1979. Regionally, there was markedly low extent in the eastern Weddell Sea, while extent in the sector between the Ross and Amundsen Seas was well above average. Slightly above-average extent remained along much of the East Antarctic coast.

CIRES scientist and ASINA-contributor Ted Scambos is currently in Antarctica studying Thwaites Glacier as part of the International Thwaites Glacier Collaboration, a five-year partnership between the US National Science Foundation and the UK Natural Environment Research Council. Scambos is the lead American scientific coordinator for the mission and a member of the Thwaites-Amundsen Regional Survey and Network (TARSAN) project team.

2019: The year in review

Figure 6a. This figure shows Chukchi Sea ice extent for 2019, 2018, and 2012, along with the 1981 to 2010 median and minimum and maximums for different periods. ||Credit: Kevin Wood, University of Washington Joint Institute for the Study of the Atmosphere and Ocean (JISAO) and the NOAA Pacific Marine Environmental Laboratory | High-resolution image

Figure 6a. This figure shows Chukchi Sea ice extent for 2019, 2018, and 2012, along with the 1981 to 2010 median and minima and maxima for different periods.

Credit: Kevin Wood, University of Washington Joint Institute for the Study of the Atmosphere and Ocean (JISAO) and the NOAA Pacific Marine Environmental Laboratory
High-resolution image

Figure 6b. This figure shows the daily Bering Sea ice extent for October through June 2017 to 2018 and 2018 to 2019 compared to average. This figure is based on NSIDC Sea Ice Index data (top). It also shows a Bering Sea ice extent map for April 1 of 2013, 2018, and 2019, the date of the average maximum extent for the region, from MASIE (bottom). ||Credit: National Snow and Ice Data Center|High-resolution image

Figure 6b. The graph, based on NSIDC Sea Ice Index Data, shows the daily Bering Sea ice extent for October through June 2017 to 2018 and 2018 to 2019 compared to average. The three maps show Bering Sea ice extent for April 1 in 2013, 2018, and 2019, the date of the average maximum extent for the region, from the Multisensor Analyzed Sea Ice Extent (MASIE) product.

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

Throughout the year, below average extent characterized Arctic sea ice, but with much variation. Overall, winter extent was not as low as compared to the previous four years from 2015 to 2018. The seasonal maximum, reached on March 13, was seventh lowest in the satellite record. The seasonal onset of melt was particularly early, contributing to record low extent during April. During May and June, the rate of ice loss remained well below average. Extent dropped to record low levels in mid-July through early August but the loss then slowed considerably compared to average. The minimum extent, reached on September 18, tied with 2007 and 2016 as the second lowest extent in the satellite record at 4.15 million square kilometers (1.60 million square miles). Autumn freeze up was initially slow, particularly in the Chukchi Sea (Figure 6a). Here, sea ice extent was at record low levels during October and November; sea surface temperatures remained 5 to 7 degrees Celsius (9 to 13 degrees Fahrenheit) above average well into the autumn.

As was also the case in 2018, the Bering Sea had extremely low sea ice cover during the winter of 2019 (Figure 6b). NSIDC Distributed Active Archive Center scientist and ASINA-contributor Walt Meier was a co-author on a recently-published study (Thoman et al., 2020) reporting that the extreme low sea ice extent in this region was unlikely to have occurred without anthropogenic warming.

Air temperatures in the Arctic region were above average throughout the year, particularly during spring and summer. Zach Labe of the University of California, Irvine, using data from the NCEP/NCAR Reanalsysis, noted that 925 mb air temperatures north of 70 degrees N latitude were among the three highest—since the satellite record began in 1979—for all months between April and October, including record highs in May and August. The NASA Goddard Institute for Space Studies data record shows that the 2019 annual average Arctic temperatures were the second highest in the satellite record, below 2016. Sea surface temperatures, as shown in Upper layer Temperature of the Polar Oceans (UpTempO) buoys, were above average throughout the summer, with temperatures in many ice-free areas exceeding 5 degrees Celsius (9 degrees Fahrenheit) above average. Warm ocean conditions lingered well into autumn, inhibiting ice growth.

In the Antarctic, the summer extent (January through March) was higher than in recent years, but still below the 1981 to 2010 average. The winter extent reached near-average levels until a steep decline in the early spring put extent well below average, with near record low extent by November. More moderate declines thereafter kept extents low, but well above record values, through the end of 2019.

A look back at the 2010s

Figure 7a. This figure shows decadal-average daily sea ice extent for the Arctic (top) and Antarctic (bottom). ||Credit: National Snow and Ice Data Center|High-resolution image

Figure 7a. This figure shows decadal-average daily sea ice extent for the Arctic (top) and the Antarctic (bottom).

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

Figure 7b. This figure shows the September 2019 Arctic sea ice extent (in white), overlaid with contours (in magenta) of decadal average September extents for the 1980s, 1990s, 2000s, and 2010s. Image basemap from NASA Blue Marble. ||Credit: National Snow and Ice Data Center|High-resolution image

Figure 7b. This figure shows the September 2019 Arctic sea ice extent (white), overlaid with contours (magenta) of decadal average September extents for the 1980s, 1990s, 2000s, and 2010s. The image base map is from the NASA Blue Marble.

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

Arctic sea ice extent was persistently low through the decade, punctuated by the record low September minimum of 2012. Overall, eight of the ten lowest September monthly average extents in the satellite record occurred during the past decade and the thirteen lowest extents have occurred in the last thirteen years from 2007 to 2019. Because consistently low extents defined the decade, the September trend was essentially zero over 2010 to 2019. October and April showed the largest downward trends during the decade of 10.3 percent and 8.3 percent, respectively. This may reflect later freeze up and earlier melt onset indicative of higher spring and autumn temperatures. However, caution should be used in interpreting trends over a ten-year period because year-to-year variations are high and outliers can strongly affect the trend value over such a short period. Another way to examine decadal changes is by comparing decadal averages. Extent in the 1990s was lower than the 1980s, extent in the 2000s was lower than the 1990s, and the 2010s had the lowest extent (Figure 7a and 7b).

The story is much different in the Antarctic. Ice extents between the decades are nearly indistinguishable from each other (Figure 7a). The 1980s had slightly lower extents during March through June and the 2010s had slightly higher extents because of record high extents earlier in the decade. But overall, the differences are small.

Arctic thickness and volume also remained low throughout the decade, as indicated by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) volume estimates and thickness estimates from the European Space Agency (ESA) CryoSat-2 satellite. Sea ice age fields show that multiyear ice, or ice that has survived at least one summer melt season, covered about 30 percent of the Arctic Ocean winter ice cover on average during the 2010s compared to about 50 percent in the 1980s. The oldest ice (more than 4-years old), which once covered about 30 percent of the Arctic Ocean in the 1980s, has nearly disappeared by the end of this decade.

There were significant research advances in the past decade, far more than can be recapped here. However, we discuss a few as examples. First, our ability to observe the ice greatly increased with the advent of satellite altimeters allowing researchers to estimate thickness over the entire Arctic Ocean. The European Space Agency CryoSat-2 satellite was launched at the beginning of the decade in April 2010, while the NASA ICESat-2 satellite, short for Ice, Cloud and land Elevation Satellite, launched near the end of the decade. Also spanning the decade was NASA Operation IceBridge, an airborne mission that flew over sea ice and land ice for over 10 years, filling in key observational gaps between ICESat, which de-orbited in 2010, and ICESat-2, which launched in 2018.

Modeling studies helped gain a better understanding of what the future holds. Countering speculation after the 2007 record low extent that a sea ice “tipping point” may have been reached, modeling studies (e.g., Tietsche et al., 2011) show that a tipping point scenario is unlikely. Over the long-term, it seems that sea ice is responding largely linearly to rising carbon dioxide levels, suggesting that our future emission trajectory will determine when and whether ice-free summer conditions will occur (Notz and Stroeve, 2016). Under our current emission trajectory, ice-free conditions are likely in the coming decades. However, modeling studies indicate that natural climate variability will play a big role in determining the first occurrence of a seasonally ice free Arctic Ocean, with at least a 20-year uncertainty window (Jahn et al., 2016).

There was great interest in potential links between strong Arctic warming and mid-latitude weather patterns. Jennifer Francis at the University of Rutgers and Steve Vavrus at the University of Wisconsin (Francis and Vavrus, 2012) argued for a link between the Arctic warming and changes in the jet stream that would result in more extremes in mid-latitude weather. This initiated heated debate within the science community. Some studies found support for the hypothesis, but others presented contradicting evidence (Cohen et al., 2019). At this point, the issue remains open.

The Intergovernmental Panel on Climate Change recently published their Special Report on the Oceans and Cryosphere in a Changing Climate, providing an overview of the state of the science.

Further Reading

Cohen, J. and co-authors. 2019. Divergent consensuses on Arctic amplification influence on midlatitude severe winter weather. Nature Climate Change. doi:10.1038/s41558-019-0662-y.

Francis, J. A., and S. J. Vavrus. 2012. Evidence linking Arctic amplification to extreme weather in mid-latitudes. Geophysical Research Letters. doi:10.1029/2012GL051000.

Jahn, A., J. E. Kay, M. M. Holland, and D. M. Hall. 2016. How predictable is the timing of a summer ice-free Arctic? Geophysical Research Letters. doi:10.1002/2016GL070067.

Notz, D., and J. Stroeve. 2016. Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission. Science. doi:10.1126/science.aag2345.

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

Tietsche, S., D. Notz, J. H. Jungclaus, and J. Marotzke. 2011. Recovery mechanisms of Arctic summer sea ice. Geophysical Research Letters. doi:10.1029/2010GL045698.

Wild ride in October

October daily sea ice extent went from third lowest in the satellite record at the beginning of the month to lowest on record starting on October 13 through October 30. Daily extent finished second lowest, just above 2016, at month’s end. Average sea ice extent for the month was the lowest on record. While freeze up has been rapid along the coastal seas of Siberia, extensive open water remains in the Chukchi and Beaufort Seas, resulting in unusually high air temperatures in the region. Extent also remains low in Baffin Bay.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for October 2019 was 5.67 million square kilometers (2.19 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

Arctic sea ice extent averaged for October 2019 was 5.66 million square kilometers (2.19 million square miles), the lowest in the 41-year continuous satellite record. This was 230,000 square kilometers (88,800 square miles) below that observed in 2012—the previous record low for the month—and 2.69 million square kilometers (1.04 million square miles) below the 1981 to 2010 average. Daily ice extent began tracking below 2012 levels on October 13 and continued to do so through the end of the month, which was enough to reach a new record monthly low at 5.66 million square kilometers (2.19 million square miles). The Arctic gained only 2.79 million square kilometers (1.08 million square miles) of ice in October 2019, compared to 3.81 million square kilometers (1.47 million square miles) in October 2012.

Autumn freeze up was slow during the first half of October, with most of the increases in the eastern Beaufort Sea and Laptev Sea. During the second half of the month, ice began to grow quickly along the coastal regions of the East Siberian and Laptev Seas. Sea ice also began forming around northern to north-eastern Svalbard. Overall, the ice edge remained considerably north of its average location throughout the Beaufort, Chukchi, Kara, and Barents Seas, as well as within Baffin Bay. However, around Svalbard, the sea ice has returned to near average conditions for this time of year. As of October 15, the ice extent in the Chukchi Sea is the lowest on record for this time of year.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of XXXXX XX, 20XX, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 20XX in purple, and 20XX in dotted 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 2a. The graph above shows Arctic sea ice extent as of October 31, 2019, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted 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. October sea ice gain (millions of square kilometers), 1979 to 2019, with 2019 shown in red and the climatological average ice growth in gray. October 2019 ice gain was close to average.||Credit: National Snow and Ice Data Center|High-resolution image

Figure 2b. The chart above shows October sea ice gain in millions of square kilometers from 1979 to 2019, with 2019 shown in red and the climatological average ice growth in gray. October 2019 ice gain was close to average.

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

Figure 2c: Satellite-derived sea surface temperature (SST) and temperatures at the UpTempO buoys, along with sea ice concentration. UpTempO buoys measure ocean temperature in the euphotic surface layer of the Polar Oceans. ||Credit: Figure from UpTempO at the University of Washington. |High-resolution image

Figure 2c. This map shows satellite-derived sea surface temperature (SST) and temperatures at the Upper layer Temperature of the Polar Oceans (UpTempO) buoys, along with sea ice concentration. UpTempO buoys measure ocean temperature in the euphotic surface layer of the Polar Oceans.

Credit: University of Washington
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Figure 2d. This figure shows air temperatures compared to average for October 2019. This includes a cross section (latitude by height, up to the 500 hPa level) along the 180 degrees E meridian, which is the date line and cuts through the Chukchi Sea. The prominent area in red at and near the surface manifests the extensive open water in the Chukchi Sea. ||Credit: NOAA/ESRL Physical Sciences Division. ||Credit: NCEP/NCAR Reanalysis| High-resolution image

Figure 2d. This figure shows air temperatures compared to average for October 2019. This is a cross section (latitude by height, up to the 500 hPa level) along the 180 degrees E meridian, which is the date line and cuts through the Chukchi Sea. The prominent area in red at and near the surface manifests the extensive open water in the Chukchi Sea.

Credit: NOAA/ESRL Physical Sciences Division.
High-resolution image

Ice growth through October 2019 averaged 89,900 square kilometers (34,700 square miles) per day. This was similar to the average rate of ice growth in October of 89,100 square kilometers (34,400 square miles) per day. However, the growth rate varied greatly during the month. On October 1, extent tracked 682,000 square kilometers (263,000 square miles) above that for the same day in 2012. However, ice growth was slow, and by October 13, extent began tracking below 2012, setting new record daily lows during the latter half of the month. On October 18, extent was 3.08 million square kilometers (1.19 million square miles) below the 1981 to 2010 average, the largest daily departure from average observed in the satellite data record. Ice growth rates increased during the last two weeks of the month so that by October 30, the extent started tracking above that recorded in 2016.

Overall, sea ice extent increased 2.79 million square kilometers (1.08 square miles) in October 2019. The largest October ice gain was in 2008 (4.22 million square kilometers; 1.63 million square miles), followed closely by 2012 (3.81 million square kilometers; 1.47 million square miles) and 2007 (3.70 million square kilometers; 1.43 million square miles) (Figure2b). However, this October, sea surface temperatures remained relatively high (2 to 5 degrees Celsius; 36 to 41 degrees Fahrenheit) in early October throughout large areas of the Chukchi, Laptev, Kara, and Barents Seas (Figure 2c). High sea surface temperatures imply considerable heat storage in the ocean surface layer, consistent with delayed freeze up in those regions.

Air temperatures at 925 hPa level (about 2,500 feet above the surface) for the month were 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above average over most of the Arctic Ocean, with temperatures north of Greenland reaching 7 degrees Celsius (13 degrees Fahrenheit) above the 1981 to 2010 average. Below average air temperatures were only found southeast of Svalbard (on the order of 1 to 2 degrees Celsius, or 2 to 4 degrees Fahrenheit). Of particular interest are the unusually high temperatures at and near the surface in the Beaufort and Chukchi Seas due to the extensive open water there. These manifest large energy fluxes from the ocean to the atmosphere, as the warm ocean water cools to the freezing point. The vertical cross section (latitude by height) of air temperatures expressed as departures from average along the 180oE meridian (the date line, which cuts through the Chukchi Sea) shows this effect clearly (Figure 2d). Unusually high temperatures in the Beaufort and Chukchi Seas will linger until the ocean surface freezes over.

October 2019 compared to previous years

Figure 3. Monthly XXXXX ice extent for 1979 to 201X shows a decline of X.X percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly October ice extent for 1979 to 2019 shows a decline of 9.8 percent per decade.

Credit: National Snow and Ice Data Center
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Monthly sea ice extent reached a record low in October as assessed over the period of satellite observations. The linear rate of sea ice decline for October is 81,400 square kilometers (31,400 square miles) per year, or 9.8 percent per decade relative to the 1981 to 2010 average.

Ice returns to “normal” near Svalbard

Figure 4. Sea ice extent around Svalbard has returned to the 1981 to 2010 median position for this time of year, as shown by the Synthetic Aperture Radar (SAR) data from the Sentinel-1 mission for October 28, 2019. ||Credit: Norwegian Meteorological Institute. | High-resolution image

Figure 4. Sea ice extent around Svalbard has returned to the 1981 to 2010 median position for this time of year, as shown by the Synthetic Aperture Radar (SAR) data from the Sentinel-1 mission for October 28, 2019.

Credit: Norwegian Meteorological Institute
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Recent winters have seen unusually low ice extent in the Barents Sea. Several studies have demonstrated a link between reduced winter ice in this region and increased ocean heat transport from the north Atlantic that prevents ice formation. However, the ocean heat transport is variable, and weakening could allow for temporary recovery of winter ice conditions in this region despite a warming climate. This appears to have been the case last winter, when the ice edge in the Barents Sea returned to its 1981 to 2010 average position. Early evidence suggests that this recovery may continue into the coming winter. Synthetic Aperture Radar (SAR) data from the Sentinel-1 mission for October 28 (Figure 4) shows the ice extent around Svalbard has returned to the 1981 to 2010 median position for this time of year. However, extent still remains much below average over most of the northern Barents Sea.

Update on sea ice age

Figure 5. Sea ice age for October 22 to 28 for 1985 (top left) and 2019 (top right), and timeseries of ages for that week from 1985 to 2019 (bottom) from NSIDC’s EASE-Grid Sea Ice Age, Version 4. ||Credit: National Snow and Ice Data Center | High-resolution image

Figure 5. The top left map shows sea ice age for October 22 to 28, 1985 while the right map shows the same week in 2019. The bottom graph shows a time series of ages for that week from 1985 to 2019 from the NSIDC EASE-Grid Sea Ice Age, Version 4.

Credit: National Snow and Ice Data Center
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After the sea ice minimum in September, the remaining sea ice had its “birthday,” aging one year in the NSIDC sea ice age fields. Much of the Arctic is now covered by second-year (1- to 2-year-old) ice, meaning ice that grew over the 2018 autumn and 2019 winter and survived the melt season. There is also already about 1 million square kilometers (386,100 square miles) of ice that has grown since the September 2019 minimum—the 0- to 1-year-old category—but there is substantially less ice older than two years than there used be—about one-third of the amount “old ice” as there was in the mid-1980s and about one-half as much as there was as recently as the mid-2000s.

IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC)

Figure 6. The IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) Summary for Policy Makers Report shows the observed and modeled historical changes in the ocean and cryosphere since 1950, as well as the future projections under a low emission scenario that limits the global warming to less than 2 degrees Celsius (4 degrees Fahrenheit), compared to a high emission scenario where global temperatures rise above 4 degrees Celsius (7 degrees Fahrenheit). Changes are shown changes relative to 1986-2005 for: (a) global mean surface air temperature; (b) global-mean sea surface temperature; (c) number of surface ocean marine heatwave days; (d) global ocean heat content (0 to 2000 meter depth); (e) Greenland mass loss; (f) Antarctic mass loss; (g) glacier mass loss; (h) global mean surface pH; (i) global mean ocean oxygen averaged over 100 to 600 meter depth; (j) Arctic sea ice; (k) Northern Hemisphere snow cover; (l) near-surface permafrost area and (m) global sea level. ||Credit: International Panel on Climate Change (IPCC). | High-resolution image

Figure 6. The Intergovernmental Panel on Climate Change (IPCC) Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) Summary for Policymakers shows the observed and modeled historical changes in the ocean and cryosphere since 1950, as well as the future projections under a low emission scenario that limits the global warming to less than 2 degrees Celsius (4 degrees Fahrenheit), compared to a high emission scenario where global temperatures rise above 4 degrees Celsius (7 degrees Fahrenheit). Changes are shown relative to 1986 to 2005 for: (a) global mean surface air temperature; (b) global-mean sea surface temperature; (c) number of surface ocean marine heatwave days; (d) global ocean heat content (0 to 2000 meter depth); (e) Greenland mass loss; (f) Antarctic mass loss; (g) glacier mass loss; (h) global mean surface pH; (i) global mean ocean oxygen averaged over 100 to 600 meter depth; (j) Arctic sea ice; (k) Arctic snow cover; (l) near-surface permafrost area and (m) global sea level.

Credit: International Panel on Climate Change (IPCC)
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In late September, the Intergovernmental Panel on Climate Change (IPCC) released a new report on the state of the oceans and the cryosphere, highlighting observed changes and forecasts of what may occur in the future. The report provides a timely update on how the cryosphere is changing and its implications for society and ecosystems. It also highlights the high confidence in rates of Arctic sea ice loss and its causes, with anthropogenic forcing and natural climate variability playing nearly equal roles.

NSIDC scientist Julienne Stroeve was one of the contributors to the chapters on sea ice and Arctic amplification—the outsized rise in Arctic air temperatures compared to the globe as a whole. One of the drivers of the special report is recognition that the oceans play a key role in the changing climate system, absorbing 90 percent of the excess heat within Earth’s system and up to a third of the carbon dioxide. Sea ice also reflects much of the sun’s energy back out to space, helping to keep the planet cooler than it otherwise would be. There is high confidence that the Arctic sea ice cover will continue to shrink (Figure 6).

The effects of anthropogenic warming are not as clear in the Antarctic, in particular for sea ice trends. This results in low confidence in any forecast of how Antarctic sea ice will evolve. The report also highlights how permafrost and snow cover are expected to change, as well as sea level rise from glacier and ice sheet mass losses. Given that the Antarctic ice sheet is starting to contribute more each year to global mean sea level rise, the potential for a meter (3.28 feet) of sea level rise by the end of the century remains possible. A key message of the report is that limiting global warming to a total of less than 2 degrees Celsius (4 degrees Fahrenheit) by the end of the century will help to mitigate the negative effects of climate change.

Sloshing Around in the Polar Twilight

The end of the Arctic sea ice melt season is nigh. The last couple of weeks have seen small rises and falls in ice extent, primarily due to changes in wind patterns. However, falling temperatures will soon accelerate the pace of ice growth.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX XX, 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for September 16, 2019, was 4.21 million square kilometers (1.62 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

Arctic sea ice extent was 4.21 million square kilometers (1.62 million square miles) on September 16, which is likely near the seasonal minimum extent that is expected within the next week. The last two weeks have seen periods of declining extent along with periods of little change or even gains in extent. From August 30 through September 5, there was a total loss of about 320,000 square kilometers (123,600 square miles). The ice cover then experienced an increase in extent from September 7 through 10. From September 10 through 16, the decline resumed, dropping 118,000 square kilometers (45,600 square miles).

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of XXXXX XX, 20XX, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 20XX in purple, and 20XX in dotted 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 2a. The graph above shows Arctic sea ice extent as of September 16, 2019, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted 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 average sea level pressure in the Arctic in millibars (hPa) for September 5 to 10, 2019. Yellows and reds indicate high air pressure; blues and purples indicate low pressure. ||Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division |High-resolution image

Figure 2b. This plot shows average sea level pressure in the Arctic in millibars (hPa) for September 5 to 10, 2019. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

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

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars (hPa) for September 10 to 14, 2019. Yellows and reds indicate high air pressure; blues and purples indicate low pressure. ||Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division |High-resolution image

Figure 2c. This plot shows average sea level pressure in the Arctic in millibars (hPa) for September 10 to 14, 2019. Yellows and reds indicate high air pressure; blues and purples indicate low pressure.

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

Rises and falls in extent are not unusual when nearing the sea ice minimum; the sea ice edge is in near-equilibrium with ocean and atmospheric temperatures. However, variable winds can either push the edge outward to increase ice extent or compact areas of lower-concentration ice to decrease ice extent. From August 26 to August 30, the overall change in extent was near zero; surface winds as depicted in the NCEP Reanalysis during this period pushed ice southward in Beaufort, Chukchi, and East Siberian Seas sectors, while winds from the south led to declines in extent in the East Greenland and Barents Seas.

From August 30 through September 5, strong winds from the south in the Beaufort, Chukchi, and East Siberian Seas pushed the ice edge northward. Essentially, the expansion at the end of August was reversed. Ice loss in the East Greenland Sea and the Canadian Archipelago also contributed to the overall extent decline during this period.

Conditions changed once again from September 5 through September 10. Extent declined only slightly until September 7 and then increased. Again, variable winds played a leading role. Winds from the north persisted on the Pacific side of the Arctic Ocean, but strong winds from the west in the Barents, Kara, and East Greenland Seas, as indicated by strong low pressure centered near the North Pole (Figure 2b), led to an increase in extent there. The Canadian Archipelago region also gained ice, reflecting low temperatures and the onset of freeze-up.

After September 10, the decline in ice extent resumed, with losses particularly north of Svalbard and between Svalbard and Franz Josef Land. This was related to northward winds as a low pressure center moved south to the east of Greenland. To a lesser degree, the ice also retreated northward on the Pacific side, also related to northward winds in the Chukchi and East Siberian Sea sectors. Southward winds prevailed in the Beaufort Sea, but these did not extend the ice edge southward, possibly because of warm waters that melted ice. Ice growth continued in the Canadian Archipelago.

Sea ice hanging on in the Beaufort Sea

Figure 3. This shows a true-color composite image of a tongue of ice that has persisted in the eastern Beaufort Sea. This tongue mostly consists of thin, small floes of ice close to melting completely, interspersed by thicker, large floes and (likely) multi-year ice. Image taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the NASA Terra satellite on September 9, 2019. ||Credit: Land Atmosphere Near-Real Time Capability for EOS (LANCE) System, NASA/GSFC. |High-resolution image

Figure 3. This shows a true-color composite image of a tongue of ice that has persisted in the eastern Beaufort Sea. This tongue mostly consists of thin, small floes of ice close to melting completely, interspersed by thicker, large floes and (likely) multi-year ice. Image taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the NASA Terra satellite on September 9, 2019.

Credit: Land Atmosphere Near-Real Time Capability for EOS (LANCE) System, NASA/GSFC.
High-resolution image

While most of the ice in the Beaufort Sea has melted out well beyond the Alaskan and Canadian coasts, a tongue of ice has persisted in the eastern Beaufort, just off the western coast of Banks Island. MODIS imagery from NASA Worldview shows that this tongue mostly consists of thin, small floes of ice close to melting completely, interspersed by thicker, large floes and (likely) multi-year ice. Most of this ice will likely survive the melt season.

 

Shipping passages and the MOSAiC expedition

The southern (Amundsen) route of the Northwest Passage appears to be open, but only via the narrow Bellot Strait between Somerset Island and the Boothia Peninsula; the wider passage through Peel Sound on the west side of Somerset Island still has ice in the mouth of the sound. The Northern Sea Route is open with the largest constriction just east of Severnaya Zemlya.

The German icebreaker Polarstern will leave port from Tromso, Norway, on September 20 and head north into the ice. It will be frozen into Arctic sea ice for the next year as part of the MOSAiC expedition, and scientists aboard will conduct numerous experiments—collecting data on ocean, ice, and atmospheric conditions. The U.S. lead scientist for the project, Matthew Shupe, is at the Cooperative Institute for Research in Environmental Sciences (CIRES), of which NSIDC is a part. NSIDC senior research scientist Julienne Stroeve will be on the ship for several weeks this coming winter. Readers can expect much more information on MOSAiC from CIRES in the coming months.

Dead heat

At mid-month, Arctic sea ice extent is tracking close to 2012, the year with the lowest minimum in the satellite record. Sea ice volume is also tracking at low levels. Smoke from Siberian wildfires continues to cover much of the Pacific side of the Arctic Ocean, but as solar input declines this late in the melt season, it is unlikely to impact sea ice loss.

Overview of conditions

Figure 1a. Arctic sea ice extent for XXXX XX, 20XX was X.XX million square kilometers (X.XX 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 1a. Arctic sea ice extent for August 14, 2019 was 5.04 million square kilometers (1.95 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

Comparison map

Figure 1b. This map compares Arctic sea ice extents between August 14, 2012 and August 14, 2019 from the NSIDC comparison tool.

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

From August 1 to 14, sea ice extent declined at a daily rate of 91,000 square kilometers (35,000 square miles), still above the 1981 to 2010 rate of decline of 71,000 square kilometers (27,400 square kilometers) during this period. However, this is still below the decline of 112,000 square kilometers (43,000 square miles) per day observed in 2012. At the beginning of the month, the 2019 ice extent was well below 2012. Because the decline through August was slower, the 2019 and 2012 sea ice extents are now close to each other. Because 2012 is a leap year, and our tracking follows the day of the year, August 13 in 2012 is August 14 in non-leap years. The ice extent for August 14, 2019 is 5.04 million square kilometers (1.95 million square miles), approximately 100,000 square kilometers (38,600 square miles) higher than for August 14, 2012 (Figure 1a).

Sea ice retreat in the first half of August 2019 was mainly in an area of patchy sea ice in the East Siberian Sea and along the ice edge in the northern Beaufort and Chukchi Seas. The Northern Sea Route appears to be open in our satellite-based mapping, but ice may remain in some areas. The Northwest Passage is still closed. There was little change in the ice edge in the Svalbard region and northern Barents and Laptev Seas. However, areas of low sea ice concentration are present along much of the remaining ice edge.

A comparison of 2019 and 2012 ice extent for August 14 shows remarkable similarities. In 2012, some patchy ice remained in the east Siberian Sea; however, the ice edge in the northeastern Beaufort and northern Chukchi Seas was further north, and some larger channels in the Canadian Archipelago were open (Figure 1b).

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of XXXXX XX, 20XX, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 20XX in purple, and 20XX in dotted 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 2a. The graph above shows Arctic sea ice extent as of August 14, 2019, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted 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 July 1 - 14, 2019. 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 Division |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 August 1 to 13, 2019. 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 Division
High-resolution image

Over the first half of the month, air temperatures along the Siberian coast at the 925 hPa level (about 2,500 feet above the surface) were generally 2 to 7 degrees Celsius (4 to 13 degrees Fahrenheit) above the 1981 to 2010 average, and 1 to 6 degrees Celsius (2 to 11 degrees Fahrenheit) above average over the Canadian Archipelago (Figure 2b). This was partly balanced by below-average temperatures in northern Scandinavia and the Kola Peninsula by 4 to 6 degrees Celsius (7 to 11 degrees Fahrenheit), a sharp counterpoint to the near-record heat of the late July European heat wave. Near-average temperatures prevailed over the central Arctic Ocean and slightly lower-than-average temperatures were present along the North Slope of Alaska and northwestern Canada. The atmospheric circulation was characterized by high pressure over the Northern Pacific, the Aleutians, and Greenland, and by a center of lower air pressure over northern European Russia. This combination drove cool Arctic air into Scandinavia and easternmost Russia.

Smoke gets in your ice

Figure 3. This NASA Worldview MODIS mosaic image from August 10, 2019, shows the locations of wildfires in the Arctic as detected by thermal images (not shown). Red areas indicate wildfires. Huge areas of burning forests in Siberia have filled the air with smoke over much of the Pacific side of the Arctic Ocean.||Credit: NASA Worldview| High-resolution image

Figure 3. This NASA Worldview image from August 10, 2019, shows the locations of wildfires in the Arctic as detected by thermal images (not shown). Red areas indicate wildfires. Huge areas of burning forests in Siberia have filled the air with smoke over much of the Pacific side of the Arctic Ocean. This image was taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the NASA Terra satellite.

Credit: NASA Worldview
High-resolution image

Huge areas of burning forests in Siberia have filled the air with smoke over much of the Pacific side of the Arctic Ocean. However, at this late stage in the melt season, with rapidly declining solar input, it is unlikely to have much impact on sea ice loss. The fires are a result of the very warm and dry spring and summer conditions over the eastern Siberian Arctic.

There is such a thing as too thin

Figure 4a. This figure shows average Arctic sea ice thickness by month for several recent years as determined by PIOMAS.||Credit: Axel Schweiger, University of Washington| High-resolution image

Figure 4a. This figure shows average Arctic sea ice thickness by month from 1980 t0 2019 as determined by the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS).

Credit: Axel Schweiger, University of Washington
High-resolution image

Figure 4b. This map shows Arctic sea ice thickness difference from average, relative to 2011 to 2018, from PIOMAS. ||Credit: Axel Schwieger/University of Washington| High-resolution image

Figure 4b. This map shows Arctic sea ice thickness in July 2019 as a difference from average (in meters), relative to 2011 to 2018, from the Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS).

Credit: Axel Schweiger, University of Washington
High-resolution image

Arctic sea ice volume, as estimated by a well-validated model produced by our colleagues at the University of Washington, is tracking at low levels as seen from satellite observations (Figure 4a). Arctic sea ice cover is thus very thin in addition to being very low in extent. Average Arctic sea ice thickness is estimated to be less than half of what it was at this time of year in 1980.

Sea ice thickness follows the change in the seasons. Early in the year, cold conditions and snowfall steadily thicken the sea ice. At the start of the melt season, typically in March, the thinner southern edges of sea ice cover melt first. Hence, the average thickness of the remaining sea ice increases, even though spring ice retreat has begun. By June, when much of the Arctic Ocean surface has reached the melting point, rapid thinning of the ice pack begins. Thickness and extent both reach a minimum in September. However, even though ice extent continues to decline through August, average sea ice thickness begins to increase slightly as the thinner ice at the edge melts away. Then, after the minimum extent, typically reached in mid-September, a rapid increase of sea ice extent begins, with thin sea ice covering large areas of the Arctic Ocean in a few weeks. This rapid increase of very thin ice reduces the average ice thickness, even though sea ice extent is increasing rapidly.

Is a new record minimum possible?

Figure 5. Comparison of several possible sea ice decline paths for 2019 with the 2012 minimum.

Figure 5. This figure compares 2019 projections of sea ice minimum extents based on rates of decline from previous years. The red line uses the rate of decline from the 1981 to 2010 reference period. The green line uses the rate of decline from 2007 to 2018 average. The dotted purple line uses the 2012 rate of decline and the dotted turquoise line uses the 2006 rate of decline.

Credit: Walt Meier, NSIDC
High-resolution image

The ASINA team conducted a revised analysis of the likely course of the 2019 Arctic summer sea ice minimum, using rates of loss from several recent years. While sea ice extent is now above extent for the same date in 2012, overall our projection for the minimum is lower than estimated in our previous post. Using the average decline rate of the past 12 years, from 2007 to 2018, the 2019 minimum is estimated to be 3.75 million square kilometers (1.45 million square miles). If the 2012 decline pattern is applied from August 14 forward, sea ice reaches 3.44 million square kilometers (1.33 million square miles). This is still above the 2012 summer minimum extent of 3.39 million square kilometers (1.31 million square miles). However, nearly all of the recent rates of sea ice loss lead to 2019 being second lowest in ice extent, surpassing 2007 and 2016.

Erratum

Readers alerted us to an error. On August 15, 2019, we reported that “Because 2012 is a leap year, and our tracking follows the day of the year, August 15 in 2012 is August 14 in non-leap years.” On August 26, 2019, we corrected this to say “August 13 in 2012 is August 14 in non-leap years.”

Europe’s heat wave moves north

Arctic sea ice extent in July tracked at record low levels for multiple individual days and for the month as a whole. During the second half of the month, air temperatures over the Arctic Ocean returned to average, while Europe experienced another record-breaking heat wave. By the end of the month, the European heat wave had moved north, enhancing melt over the Greenland ice sheet.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for July 2019 was 7.59 million square kilometers (2.93 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

Arctic sea ice extent for July 2019 set a new record low of 7.59 million square kilometers (2.93 million square miles). The monthly average extent was 80,000 square kilometers (30,900 square miles) below the previous record low set in 2012 and 1.88 million square kilometers (726,000 square miles) below the 1981 to 2010 average. On a daily basis, ice tracked at record low levels from July 10 through July 14 and July 20 through the end of the month. Ice retreated over most regions of the Arctic Ocean, especially over the Laptev Sea, northern Chukchi and Beaufort Seas, and Hudson Bay, where no ice remained at the end of the month. There was little retreat in the Barents Sea where the ice edge had already pulled back to its average northward position for this time of year. Ice also continued to linger along the coast in the East Siberian Sea near the Russian port town of Pevek and Wrangel Island. However, the sea ice concentrations in the region are now low, with many open water areas between ice floes. By the end of the month, the Northern Sea Route that links Europe and Asia through the East Siberian and Laptev Seas appeared to be essentially open, whereas the Northwest Passage (both the southern and northern routes) remained blocked by ice.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of XXXXX XX, 20XX, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 20XX in purple, and 20XX in dotted 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 2a. The graph above shows Arctic sea ice extent as of July 31, 2019, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted 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. The graph above shows Arctic sea ice extent decline per decade since satellite observations began in 1979. 1979 to 1989 is shown in light pink, the 1990s in dark pink, the 2000s in magenta, and the 201os in purple. 2019 is shown in a thick purple line ending on July 31, 2019, while the 2012 record low is also marked. ||Credit: National Snow and Ice Data Center|High-resolution image

Figure 2b. The graph above shows Arctic sea ice extent decline per decade since satellite observations began in 1979. 1979 to 1989 is shown in light pink, the 1990s in dark pink, the 2000s in magenta, and the 201os in purple. 2019 is shown in a thick purple line ending on July 31, 2019, while the 2012 record low is also marked. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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 July 2019. 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 Division | 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 July 2019. 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 Division
High-resolution image

July is typically the warmest month of the year, with the largest rate of ice loss. Sea ice extent this July declined at an average rate of 105,700 square kilometers (40,800 square miles) per day, exceeding the 1981 to 2010 average of 86,800 square kilometers (33,500 square miles) per day. Only seven previous years—1990, 1991, 2007, 2009, 2013, 2015, and 2018—experienced daily rates of ice loss exceeding 100,000 square kilometers (38,600 square miles) per day, with 2007 holding the record low of 114,200 square kilometers (44,100 square miles) per day.

Rapid ice loss for July 2019 was in part driven by warm conditions during the first half of the month. The latter half of the month, in contrast, was relatively cool over the East Siberian and Laptev Seas, as well as near Svalbard and the Canadian Arctic Archipelago, where temperatures at the 925 hPa level (about 2,500 feet above the surface) were 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) below the 1981 to 2010 average. These relatively cool conditions were the result of below average sea level pressure centered over the East Siberian Sea, coupled with above average sea level pressure over the west Siberian Plain, which brought cold air southwards and helped to push the ice towards the coast. However, by July 30, the heat wave that had been plaguing Europe moved north, baking Greenland with temperatures at the 925 hPa level 10 degrees Celsius (18 degrees Fahrenheit) above average while parts of the Arctic Ocean saw temperatures 1 to 7 degrees Celsius (2 to 13 degrees Fahrenheit) above average. During this heat wave, about 60 percent of the Greenland ice sheet experienced melt. Despite the fluctuations during the month, the average monthly temperature was above average over most of the Arctic Ocean (Figure 2c).

By the beginning of August, the pace of ice loss tends to drop rapidly. 2012 was an exception, when the average August ice loss rate remained quite rapid at 89,500 square kilometers per day (34,600 square miles per day), leading to a new record low for the September minimum that year. As of August 5, 2019, the total sea ice extent has dropped below 6 million square kilometers, something which has not occurred prior to 1999. Sea ice extent in September of 2019 is likely to be among the five lowest minimums recorded.

July 2019 compared to previous years

Figure 3. Monthly XXXXX ice extent for 1979 to 201X shows a decline of X.X percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly July ice extent for 1979 to 2019 shows a decline of 7.32 percent per decade.

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

In total, sea ice extent during July 2019 decreased by 3.28 million square kilometers (1.27 million square miles). This was larger than the 1981 to 2010 average loss for the month. The linear rate of sea ice decline for July from 1979 to 2019 is 693,000 square kilometers (268,000 square miles) per year, or 7.32 percent per decade relative to the 1981 to 2010 average.

Early melt brings early ice break-up and warmer ocean temperatures to the Beaufort Sea

Figure 4. Melt onset for 2019 expressed as differences (in days) with respect to 1981 to 2010 averages based on the passive microwave satellite data record. ||Credit: Data courtesy of Jeff Miller at NASA GSFC. | High-resolution image

Figure 4a. This map shows the 2019 melt onset expressed as differences (in days) with respect to 1981 to 2010 averages. Values are based on the passive microwave satellite data record.

Credit: Data courtesy of Jeff Miller at NASA Goddard Space Flight Center.
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Figure 4b. Sea surface temperature in degrees Celsius for July 31, 2019 from the University of Washington Polar Science Center UpTempO buoys and satellite-derived values from NOAA. ||Credit: National Oceanic and Atmospheric Organization| High-resolution image

Figure 4b. This map of the Arctic Ocean shows sea surface temperature in degrees Celsius for July 31, 2019. Data are from the University of Washington Polar Science Center UpTempO buoys and satellite-derived values from the National Oceanic and Atmospheric Association (NOAA).

Credit: National Oceanic and Atmospheric Association (NOAA)
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As mentioned in our July mid-month post, numerous ice floes have broken away from the main pack ice in the southern Beaufort Sea. This was in part fueled by early melt onset; ice began to melt nearly a month earlier than average (Figure 4a). Melt also started earlier than average within the northern Bering and southern Chukchi Seas and also within Baffin Bay along the west coast of Greenland. Melt onset over the central Arctic Ocean near the longitudes of the Laptev Sea, the Lincoln Sea, and parts of Hudson Bay was up to 20 days earlier than average. The timing of melt onset plays an important role in melt pond development and ice breakup, both of which allow for more solar radiation to be absorbed in the upper ocean, promoting more ice melt. The timing of melt pond development has been shown to be a useful predictor of how much ice will be left at the end of summer. The impact of this year’s early melt onset is evident in sea surface temperatures along the coast of Alaska and the Chukchi Sea, which are at least 5 degrees Celsius (9 degrees Fahrenheit) above average (Figure 4b).

Wildfires continue to rage across Arctic region

Figure 6a. MODIS image from July 24, 2019. Red dots show locations of fires. ||Credit: National Snow and Ice Data Center| High-resolution image

Figure 5a. This image from July 24, 2019 from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) sensor shows the locations of fires (red dots) in the Arctic. Since the beginning of June, more than 100 large wildfires have been observed

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

Figure 6b. Fire radiative power from the Copernicus Atmosphere Monitoring Service (CAMS). Fire radiative power is a measure of heat output from wildfires as shown for June 2019 (red) and the 2003-2018 average (grey). ||Credit: National Snow and Ice Data Center| High-resolution image

Figure 5b. This figure shows the Total Fire Radiative Power (TFRP) in the Arctic Circle detected by the Copernicus Atmosphere Monitoring Service (CAMS). Fire radiative power is a measure of heat output from wildfires as shown for June 2019 (red) and the 2003 to 2018 average (grey).

Credit: National Snow and Ice Data Center
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Figure 6c. Caption Needed||Credit: NASA Worldview|High-resolution image

Figure 5c. In this photo taken during a NOAA flight north of Utqiagvik, Alaska, sea ice appears to be highly decayed with deep melt ponds.

Credit: Kevin Woods, NOAA Pacific Marine Environmental Laboratory
High-resolution image

Another factor that plays a role in ice melt is deposition of dark soot from wildfires on the highly reflective snow and ice surfaces, allowing more of the sun’s energy to be absorbed. Since the beginning of June, more than 100 large wildfires have been observed over Arctic lands, including Alaska, Greenland, and Siberia (Figure 5a). Smoke from these fires has been observed to blow across Greenland and over sea ice areas. Wildfires do not only deposit soot, they also pose a health hazard to local communities. According to the European Union Copernicus Atmospheric Monitoring Service (CAMS), the fires this year are far more intense than normal, with a Total Fire Radiative Power (TFRP) up to about 10 times higher than average for a given date (Figure 5b). TFRP is derived from Moderate Resolution Imaging Spectroradiometer (MODIS) data and incorporates the thermal radiation (intensity of buring) and the amount of smoke produced. Further, the fires release a substantial amount of carbon dioxide. The report notes that these fires have released as much carbon dioxide into the atmosphere as the annual total emissions of Sweden, or more than 50 megatons of this greenhouse gas; this is more than all fires within the same month between 2010 and 2018.

The National Oceanic and Atmospheric Administration (NOAA) has been tracking the melt season with aircraft flights over the ice north of Utqiagvik, Alaska, as part of its Arctic Heat program. While onboard some of these flights in mid-July, Kevin Woods of the NOAA Pacific Marine Environmental Lab in Seattle, Washington took several photos of the sea ice (Figure 5c). The ice appeared to be highly decayed with deep melt ponds, many melted completely through the ice. In other areas, the ice was sparse with isolated floes surrounded by open water. Much of this is likely to melt out completely by the end of the summer.

Open water again north of Greenland

Figure 7. Sea ice as seen from an aircraft over Utqiagvik, Alaska. The ice appeared to be highly decayed with deep melt ponds, many melted completely through the ice. ||Credit: Kevin Woods, NOAA Pacific Marine Environmental Lab | High-resolution image | High-resolution image

Figure 6. This true-color composite image taken by the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) sensor shows sea ice as seen from an aircraft over Peary Land, Northeast Greenland. Areas of open water have appeared on the north coast of Greenland where two large floes that were fast ice broke away last week.

Credit: NASA
High-resolution image

Once again, areas of open water have appeared on the north coast of Greenland. A similar situation was observed during two periods in 2018, including one in mid-winter and one in late summer. Two large floes that were fast ice (attached to the coast) broke away last week (Figure 6). The largest floe is roughly 110 kilometers by 65 kilometers (70 miles by 40 miles), about 50 percent larger than the state of Rhode Island.

Antarctic update

Figure 8. Antarctic sea ice extent for May 2019 was 8.80 million square kilometers (3.40 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 7. Antarctic sea ice extent for May 2019 was 15.30 million square kilometers (5.91 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 growth has been slightly slower than average since the end of the austral summer in March, pushing an already-low sea ice extent lower. By July, Antarctic sea ice extent was tracking among the lowest in the continuous satellite record. The other near-record years were widely dispersed (1983, 1986, 2002, and 2017), underscoring the high variability of Antarctic sea ice. While an overall positive linear trend is still evident in the 40-year Antarctic sea ice extent record, variability dominates, with 2014 being a record high maximum and 2017 a record low maximum extent.

Our site has from time to time noted the comings and goings of the Maud Rise Polynya, an opening within the pack ice thought to form when deeper warm water is forced to the surface. In late July, a similar feature formed in the Cosmonaut Sea, the name for the area of the Southern Ocean along the western coast of Enderby Land (40 degrees to 55 degrees E longitude). The Cosmonaut Sea Polynya has been identified and studied for many years, first in 1987. It can appear in July or August as the sea ice edge expands northward over a region near 66 degrees S, 43 degrees E, occurring in about a third of the winter sea ice seasons. The polynya is formed by a combination of ocean currents and winds that create an upward dome shape in warmer, or a few degrees above freezing, deep ocean layers. If this warmer water mixes upward, it prevents the formation of sea ice even as cold winter weather freezes adjacent areas.

References

Comiso, J. C. and Gordon, A. L. 1987. Recurring polynyas over the Cosmonaut Sea and the Maud Rise. Journal of Geophysical Research: Oceans. doi: 10.1029/JC092iC03p02819.

Schröder, D., D. L. Feltham, D. Flocco, and M. Tsamados. 2014. September Arctic sea-ice minimum predicted by spring melt-pond fraction. Nature: Climate Change. doi:10.1038/NCLIMATE2203.

Markus, T., J. C. Stroeve, and J. Miller. 2009. Recent changes in Arctic sea ice melt onset, freezeup, and melt season length. Journal of Geophysical Researchdoi:10.1029/2009JC005436.

Stroeve, J. C., T. Markus, L. Boisvert, J. Miller, and A. Barrett. 2014. Changes in Arctic melt season and implications for sea ice loss. Geophysical Research Letters. doi.org/10.1002/2013GL058951.

Warm May in the Arctic sets the stage

May saw above average temperatures over nearly all of the Arctic Ocean, Baffin Bay, and Greenland. Early sea ice retreat in the Bering Sea extended into the southern Chukchi Sea. Northern Baffin Bay and the Nares Strait have low ice cover. By month’s end, open water extended along the northeastern Alaskan and northwestern Canadian coasts, all well ahead of schedule. However, this was partly balanced by slower-than-average ice loss in the Barents Sea. At the end of May, Arctic sea ice daily extent stood at second lowest in the 40-year satellite record.

Overview of conditions

Figure 1. Arctic sea ice extent for XXXX 20XX was X.XX million square kilometers (X.XX 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 1. Arctic sea ice extent for May 2019 was 12.16 million square kilometers (4.70 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

Arctic sea ice extent averaged for May was 12.16 million square kilometers (4.70 million square miles). This is 1.13 million square kilometers (436,000 square miles) below the 1981 to 2010 average and 240,000 square kilometers (93,000 square miles) above the previous record low for the month set in May 2016. The month saw rapid ice loss in the Bering Sea and southern Chukchi Sea. During the second half of the month, an extended coastal polynya opened along the northwestern coast of the Beaufort Sea extending into the Mackenzie River Delta area. Visible MODIS imagery shows many large ice floes interspersed with open water along the ice edge and fracturing of ice further within the pack.

Although ice loss in the Barents Sea was rapid in early May, it subsequently slowed and extent slightly increased late in the month. There was nevertheless an overall ice retreat for May as a whole. Around mid-month, a polynya began to open at the north end of Baffin Bay, near the Nares Strait. At about this time, an ice arch that restrains southward ice drift in the Lincoln Sea began to fail, allowing transport of ice through the strait and creating a small polynya northwest of Greenland (discussed below). By the end of May, other polynyas started to form around the New Siberian Islands as well as Severnaya Zemlya, and open water began to develop along coastal regions in the Kara Sea and in northern Hudson Bay.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of June 3, 2019, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted 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 2a. The graph above shows Arctic sea ice extent as of June 3, 2019, along with daily ice extent data for four previous years and the record low year. 2019 is shown in blue, 2018 in green, 2017 in orange, 2016 in brown, 2015 in purple, and 2012 in dotted 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 May 2019. 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 Division|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 May 2019. 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 Division
High-resolution image

Broadly following the pattern for April, air temperatures at the 925 hPa level (approximately 2,500 feet above the surface) for May were again well above average over nearly all of the Arctic Ocean. Along the western Greenland coast, a broad area north of Greenland, and westward north of the Canadian Archipelago, temperatures were as much as 7 degrees Celsius (13 degrees Fahrenheit) above the 1981 to 2010 reference average for the month. Over much of the remainder of the Arctic Ocean, temperatures were 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) above average. By contrast, over the Barents Sea as well as along the Laptev Sea coast, temperatures were near average or up to 2 degrees (4 degrees Fahrenheit) below average. As averaged for May, there was an area of high sea level pressure, an anticyclone, centered near the pole. This pattern drew warm air from the south into Baffin Bay and into the Arctic Ocean. Also, air under an anticyclone descends and warms. Both factors help to explain the unusually high temperatures over much of the Arctic Ocean.

May 2019 compared to previous years

Figure 3. Monthly May ice extent for 1979 to 2019 shows a decline of X.X percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly May ice extent for 1979 to 2019 shows a decline of 2.74 percent per decade.

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

Overall, sea ice extent during May 2019 decreased by 1.49 million square kilometers (575,300 square miles). This was fairly close to the 1981 to 2010 average loss for the month. The linear rate of sea ice decline for May from 1979 to 2019 is 36,400 square kilometers (14,100 square miles) per year, or 2.74 percent per decade relative to the 1981 to 2010 average.

Ice arch break up in the Lincoln Sea

Figure 4. Animation from Aqua MODIS true color composite images from NASA Worldview. The animation was created using the new Worldview animation function.||Credit: NASA| High-resolution image

Figure 4. This NASA Worldview (download to view animation) image shows sea ice in the Nares Strait from April 19 to May 11. A new Worldview functions creates an animation using Aqua Moderate Imaging Spectroradiometer (MODIS) true color composite images.

Credit: NASA
High-resolution image

In most years (2007 being a notable exception), an ice arch forms during late autumn and winter at the north end of Nares Strait, the narrow passage that separates Greenland from Ellesmere Island. This arch acts as a barrier, preventing ice from the Arctic Ocean from drifting through the strait and into Baffin Bay. The arch typically breaks up in June or July, allowing ice to drift through the narrow channel. This year, the arch broke up by late March, much earlier than is typical. Since then, there has been a steady flow of ice through Nares Strait (download animation to view). Since 2000, only four other years appear to have had similar early breakups of the arch: 2007 (when no arch formed at all), 2008, 2010, and 2017 (Moore et al., 2018). Typically, strong wind events trigger the break up, but warm temperatures and thinner ice can also contribute.

Arctic sea ice variability linked to atmospheric temperature fluctuations

Figure 5. Top, this figure shows how the year-to-year sea ice area co-varies with mid-atmosphere temperatures (average of temperatures between 850 HPa to 400 HPa, or about 5000 to 25000 feet above sea level). Below, a bar graph provides the contributions of other suggested mechanisms – combined, they account for about 25 percent of the sea ice variations. The direct influence of mid-atmosphere temperature fluctuations remains as the primary cause of year-to-year sea-ice variations. ||Credit: NSIDC Sea Ice index and ERA-Interim Reanalysis | High-resolution image

Figure 5. The top figure shows how the year-to-year sea ice area co-varies with mid-atmosphere temperatures (average of temperatures between 850 HPa to 400 HPa, or about 5,000 to 25,000 feet above sea level). The below bar graph provides the contributions of other suggested mechanisms. Combined, they account for about 25 percent of the sea ice variations. The direct influence of mid-atmosphere temperature fluctuations remains as the primary cause of year-to-year sea-ice variations.

Credit: NSIDC Sea Ice Index and ERA-Interim Reanalysis
High-resolution image

While Arctic sea ice extent is declining sharply, it is also highly variable from one year to the next. Scientists from the Max Planck Institute for Meteorology (MPI-M) and the University of Stockholm have proposed that this strong variability is closely related to fluctuations in the air temperature above the Arctic Ocean driven by atmospheric heat transport into the Arctic from lower latitudes. In contrast to previous assumptions, they argue that other factors, such as the ice-albedo feedback, cloud and water vapor feedbacks, and oceanic heat transported into the Arctic together explain only 25 percent of the year-to-year sea ice extent variations. Most of the sea ice variations are thus directly caused by mid-atmospheric temperature conditions; this is evident in both observational data and climate models. Their study implies that year-to-year fluctuations in sea ice extent are easier to understand than previously thought. However, their study also suggests that it may be more difficult to predict the summer extent of Arctic sea ice from one year to the next, because the problem of predicting atmospheric heat transport is closely related to the challenges of long-term weather forecasting.

Antarctic sea ice extent exceptionally low in the Weddell and Amundsen Seas

Figure 6. Antarctic sea ice extent for May 2019 was 12.16 million square kilometers (4.69 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 6. Antarctic sea ice extent for May 2019 was 8.80 million square kilometers (3.40 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 continues to climb toward its seasonal maximum, which is expected in late September or early October. At the end of May, Antarctic sea ice extent was very close to record daily lows over the period of satellite observations, previously set for the month in 1980. Unusually low ice extent in the eastern Weddell Sea and northern Amundsen Sea are responsible for the low overall total extent, with smaller areas of open water in the eastern Wilkes Land coastal region and southwestern Indian Ocean (Cosmonaut Sea). Slightly above average sea ice extent is present in the north-central Ross Sea and northwestern Weddell Sea.

References

Kwok, R., L. Toudal Pedersen, P. Gudmandsen, and S. S. Pang. 2010. Large sea ice outflow into the Nares Strait in 2007. Geophysical Research Letters. doi: 10.1029/2009GL041872.

Moore, G. W. K. and K. McNeil. 2018. The early collapse of the 2017 Lincoln Sea ice arch in response to anomalous sea ice and wind forcing. Geophysical Research Lettersdoi:10.1029/2018GL078428.

Olonscheck, D., T. Mauritsen, and D. Notz. 2019. Arctic sea-ice variability is primarily driven by atmospheric temperature fluctuations. Nature Geoscience. doi:10.1038/s41561-019-0363-1.