A recent slowdown

Arctic extent nearly matched 2012 values through the first week of July, but the rate of decline slowed during the second week. Weather patterns were unremarkable during the first half of July.

Overview of conditions

Figure 1. Arctic sea ice extent for July 17, 2017 was 7.88 million square kilometers (3.04 million square miles). The orange line shows the 1981 to 2010 average extent for that day. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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As of July 17, Arctic sea ice extent stood at 7.88 million square kilometers (3.04 million square miles). This is 1.69 million square kilometers (653,000 square miles) below the 1981 to 2010 average, and 714,000 square kilometers (276,000 million square miles) below the interdecile range. Extent was lower than average over most of the Arctic, except for the East Greenland Sea (Figure 1). Hudson Bay was nearly ice free by mid July, much earlier than is typical, but in line with what has been observed in recent years.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of July 17, 2017, along with daily ice extent data for five previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, 2013 in purple, and 2012 as a dotted brown line. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 2b. This map compares sea ice extent for July 11 in 2017 and in 2012. White shows where ice occurred only in 2012, medium blue is where ice occurred only in 2017, and light blue is where ice occurred in both years.

Credit: National Snow and Ice Data Center
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Through the first week of July, extent closely tracked 2012 levels. The rate of decline then slowed, so that as of July 17, extent was 169,000 square kilometers (65,300 square miles) above 2012 for the same date (Figure 2a). The spatial pattern of ice extent differs from 2012, with less ice in the Chukchi and East Siberian Seas in 2017, but more in the Beaufort, Kara, and Barents Seas and in Baffin Bay (Figure 2b).

Visible imagery provides up close details

Figure 4a. Sea ice in the Canadian Archipelago on July 3, 2017. The blue hues indicate areas of widespread melt ponds on the surface of the ice. ||Credit: RESEARCHER'S NAME/ORGANIZATION *or * National Snow and Ice Data Center| High-resolution image

Figure 3a. This image from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS) shows sea ice in the Canadian Archipelago on July 3, 2017. The blue hues indicate areas of widespread melt ponds on the surface of the ice.

Credit: Land Atmosphere Near-Real Time Capability for EOS (LANCE) System, NASA/GSFC
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sea ice floes

Figure 3b. The Sentinel-2 satellite captured this image of large sea ice floes in Nares Strait on July 8, 2017.

Credit: European Space Agency
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MODIS image of arctic

Figure 3c. This false-color composite image of the Arctic is based on NASA MODIS imagery from July 4 to 10. Most clouds are eliminated by using several images over a week, but some clouds remain, particularly over the ocean areas.

Credit: NASA/Canadian Ice Service
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NSIDC primarily relies on passive microwave data because it provides complete coverage—night and day, and through clouds—and because it is consistent over its long data record. However, other types of satellite data, for example visible imagery from the NASA MODIS instrument on the Aqua and Terra satellites or from the European Space Agency Sentinel 2 satellite, can sometimes provide more detail. When skies clear, details of the ice cover can be seen, including leads, individual ice floes and melt ponds. For example, on July 3 in the Canadian Archipelago, 1-kilometer resolution MODIS imagery shows that the ice surface has a distinctive blueish hue due to the presence of melt ponds on the surface (Figure 3a). Higher resolution Sentinel-2 imagery (10 meters, Figure 3b) on the other hand provides up close detail on individual melt ponds on the ice floes.

The Arctic is a cloudy place, and generally, it is difficult to obtain a clear-sky image of the entire region. However, if images are compiled, or composited, over several days, most of the region may have at least some clear sky. This approach can yield a composite image that is mostly cloud-free. The Canadian Ice Service uses this approach to create a weekly nearly cloud-free composite image of the Arctic (Figure 3c). However, because the ice cover moves (typically several kilometers per day) and melts (during the summer), over the week-long composite period, fine details that can be seen in the daily imagery are not as evident because they have been “smeared” out over the week.

An ice-diminished Arctic

In response to diminishing ice extent, the US Navy has been holding a semi-annual symposium to bring together scientists, policy makers, and others to discuss the sea ice changes and their impacts. The seventh Symposium is taking place this week in Washington, DC, and will be attended by NSIDC scientists Mark Serreze, Walt Meier, Florence Fetterer, and Ted Scambos.

Tendency for warmer winters is increasing

A new study published this week in Geophysical Research Letters by Robert Graham at the Norwegian Polar Institute shows that warm winters in the Arctic are becoming more frequent and lasting for longer periods of time than they used to. Warm events were defined by when the air temperatures rose above -10 degrees Celsius (-14 degrees  Fahrenheit). While this is still well below the freezing point, it is 20 degrees Celsius (36 degrees Fahrenheit) higher than average. The last two winters have seen temperatures near the North Pole rising to 0 degrees Celsius. While an earlier study showed that winter 2015/2016 was the warmest recorded at that time, the winter of 2016/2017 was even warmer.

Reference

Graham, R. M., L. Cohen, A. A. Petty, L. N. Boisvert, A. Rinke, S. R. Hudson, M. Nicolaus, and M. A. Granskog. 2017. Increasing frequency and duration of Arctic winter warming events, Geophys. Res. Lett., 44, doi:10.1002/2017GL073395.

Arctic ice extent near levels recorded in 2012

Contrasting with the fairly slow start to the melt season in May, June saw the ice retreat at a faster than average rate. On July 2, Arctic sea ice extent was at the same level recorded in 2012 and 2016. In 2012, September sea ice extent reached the lowest in the satellite record. As a new feature to Arctic Sea Ice News and Analysis, NSIDC now provides a daily updated map of ice concentration in addition to the daily map of ice extent.

Overview of conditions

Figure 1. Arctic sea ice extent for June 2017 averaged 11.06 million square kilometers (4.27 million square miles).

Figure 1. Arctic sea ice extent for June 2017 averaged 11.06 million square kilometers (4.27 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
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Arctic sea ice extent for June 2017 averaged 11.06 million square kilometers (4.27 million square miles), the sixth lowest in the 1979 to 2017 satellite record. The average June 2017 extent was 900,000 square kilometers (348,000 square miles) below the 1981 to 2010 long-term average, and 460,000 square kilometers (178,000 square miles) above the previous record low set in 2016.

Continuing the pattern seen in May, sea ice extent at the end of the month remained below average in the Chukchi Sea and in the Barents Sea. Ice extent was at average levels in the Greenland Sea. Areas of low concentration ice have developed along the ice edge and coastal seas.

Based on imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) aboard the NASA Terra and Aqua satellites, summer melt ponds atop the ice cover were somewhat slow to develop. However, there is now widespread melt pond coverage in the Canadian Archipelago and the Laptev and East Siberian Seas. Data from the Advanced Microwave Scanning Radiometer 2 (AMSR-2) instrument analyzed by the University of Bremen, as well as MODIS imagery, indicate that melt ponds have also developed over the Central Arctic Ocean. Researchers in Dease Strait in Northern Canada have observed melt ponds forming about two weeks earlier than average. Melt ponds are important as they decrease the albedo or reflectivity of the ice surface, which hastens further melt.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of July 4, 2017, along with daily ice extent data for five previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, 2013 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.

Figure 2. The graph above shows Arctic sea ice extent as of July 4, 2017, along with daily ice extent data for five previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, 2013 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
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The rate of decline in ice extent was fairly steady through the month, and the average rate of decline of 81,800 square kilometers (31,600 square miles) per day was slightly faster than the 1981 to 2010 long-term average of 56,300 square kilometers (21,700 square miles) per day. On July 2, extent was the same as that recorded in 2012 and 2016. The year 2012 ended up with the lowest September extent in the satellite record.

June air temperatures were modestly above average (1 to 3 degrees Celsius or 2 to 5 degrees Fahrenheit) in a band spanning the Arctic Ocean roughly centered along the date line and the prime meridian. This contrasts with below-average temperatures over the eastern Beaufort Sea and Canadian Arctic Archipelago and the Barents and Laptev Seas (1 to 3 degrees Celsius, 2 to 5 degrees Fahrenheit). Atmospheric pressures at sea level were below-average over the Kara Sea and extending north of the Laptev Sea.

June 2017 compared to previous years

Figure 3. Monthly June ice extent for 1979 to 2017 shows a decline of 3.7 percent per decade.

Figure 3. Monthly June ice extent for 1979 to 2017 shows a decline of 3.7 percent per decade.

Credit: National Snow and Ice Data Center
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The linear rate of decline for June is 44,300 square kilometers (17,100 square miles) per year, or 3.7 percent per decade.

Ice thickness

Figure 4. Figure 4. This figure shows that sea ice thicknesses for May 2017 were below the 2000 to 2015 average over most of the Arctic Ocean (areas in blue) except for the region north and west of the Svalbard archipelago (areas in red). ||Credit: University of Washington Pan-Arctic Ice Ocean Modeling and Assimilation System

Figure 4. This figure shows that sea ice thicknesses for May 2017 were below the 2000 to 2015 average over most of the Arctic Ocean (areas in blue) except for the region north and west of the Svalbard archipelago (areas in red).

Credit: University of Washington Pan-Arctic Ice Ocean Modeling and Assimilation System
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The University of Washington Seattle Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS) regularly produces maps of ice thickness anomalies (departures from the long-term average). PIOMAS is based on a coupled ice-ocean model that is driven by data from an atmospheric reanalysis, and also assimilates data on observed ocean conditions and ice thickness (e.g., from NASA IceBridge). The PIOMAS analysis suggests that, relative to the average over the period 2000 to 2015, ice thickness for May 2017 (when the melt season was just beginning) was below average over most of the Arctic Ocean, especially in the Chukchi Sea and north of the Canadian Arctic Archipelago. A small region with above-average ice thickness is depicted over the Atlantic side of the Arctic north and west of the Svalbard Archipelago, and in the Greenland Sea. Starting the melt season with below-average ice thickness raises the likelihood of having especially low September ice extent.

Freezing degree days and ice thickness

Figure 5. The figure shows departures from average in cumulate freezing degree days, extending from July 1 for a given year through July 1 of the next year, along with the range, 15th through 85th percentile and 30th to 70th percentile values over the base period 1981 through 2010.

Figure 5. The figure shows departures from average in cumulate freezing degree days, extending from July 1 for a given year through July 1 of the next year, along with the range, 15th through 85th percentile and 30th to 70th percentile values over the base period 1981 through 2010.

Credit: National Snow and Ice Data Center
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Cumulative Freezing Degree Days (FDD) is a simple measure of how cold it has been and for how long. Cumulative FDD is the sum of daily mean temperatures below zero from some start date. Here we start on July 1. Cumulative FDD is related to ice thickness because, on average, years with longer periods of temperatures below freezing will have more ice growth. A simple empirical model that has been used by scientists relates ice thickness to the square root of cumulative FDD.

Anomalies (departures from the average) in cumulative FDD illustrate the coldness of a given period relative to the long-term average (1981 to 2010). Figure 5 shows that most of the period from July 2016 to July 2017 was extremely mild and was milder (less cold) than both 2006 to 2007 and 2011 to 2012. September of both 2007 and 2012 ended up with very low September sea ice extent. This is consistent with below-average ice thickness seen in the PIOMAS data. Although conditions cooled in May and June, this likely had little impact on ice thickness. This is because ice in the Arctic reaches its maximum thickness earlier in the season during March or April. As noted earlier, ice retreated at a fast rate throughout June. This is likely linked to a thinner than average ice cover as seen in the PIOMAS analysis.

Sudden Antarctic sea ice decline in late 2016

A slight decrease in the rate of sea ice growth at the end of June brought Antarctic sea ice extent back to daily record lows. Sea ice extent in the Bellingshausen, eastern Amundsen, and western Ross Seas was below average.

Our post on December 2016 ice conditions highlighted a precipitous drop in Antarctic sea ice extent in the Weddell and Ross Sea sectors during September, October, and November of 2016. A recent study by John Turner and colleagues links this pattern of sea ice decline to a series of strong storms, marked by long periods of warm winds from the north. These changing weather conditions are associated with large shifts in the Southern Annual Mode index (SAM index).

Further reading

Turner, J., T. Phillips, G. J. Marshall, J. S. Hosking, J. O. Pope, T. J. Bracegirdle, and P. Deb. 2017. Unprecedented springtime retreat of Antarctic sea ice in 2016, Geophysical Research Letters, 44, doi:10.1002/2017GL073656.

Sluggish ice retreat, except in the Chukchi Sea

After setting satellite-era record lows during winter, Arctic sea ice extent declined at a steady but somewhat sluggish pace during May. However, ice has retreated at a record rate in the Chukchi Sea, and open water extended to Barrow, Alaska. In the Southern Hemisphere, ice extent continues its seasonal expansion, but extent remains well below the long-term average for this time of year.

Overview of conditions

n_extn_hires

Figure 1. Arctic sea ice extent for May 2017 was 12.74 million square kilometers (4.92 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 May 2017 averaged 12.74 million square kilometers (4.92 million square miles), the fourth lowest in the 1979 to 2017 satellite record. This contrasts strongly with the past several months, when extent tracked at satellite-era record lows. May 2017 extent was 710,000 square kilometers (274,000 square miles) below the 1981 to 2010 long-term average, and 660,000 square kilometers (255,000 square miles) above the previous record low set in 2016. Sea ice extent remained below average in the Pacific sector of the Arctic and in the Barents Sea, but was slightly above average in Baffin Bay and Davis Strait towards the Labrador Sea. Ice extent was at average levels in the Greenland Sea. In the Chukchi Sea, extent was at record low levels for May.

Conditions in context

time series graph

Figure 2a. The graph above shows Arctic sea ice extent as of June 6, 2017, along with daily ice extent data for five previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, 2013 in purple, and 2012, the record low year, as a dashed line. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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temperature difference plot

Figure 2b. The plot shows differences from average for Arctic air temperatures from May 1 to 27, 2017 at the 925 hPa level (about 2,500 feet above sea level) in degrees Celsius. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA ESRL Physical Sciences Division
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For the Arctic as a whole, the rate of decline in Arctic sea ice extent through May was relatively slow. The May 2017 rate of decline was 42,800 square kilometers (16,500 square miles) per day, compared to the 1981 to 2010 average of 46,990 square kilometers (18,143 square miles) per day.

Sea ice was especially slow to retreat in the Atlantic sector of the Arctic, with little change in the ice edge in Baffin Bay and Davis Strait. The ice edge expanded in the Barents and Greenland Seas until the end of May, when the ice finally started to retreat. Most of the ice retreat in May occurred within the Pacific sector, particularly within the Sea of Okhotsk, and the Bering and Chukchi Seas.

Overall, air temperatures at the 925 hPa level were 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) below average over Eurasia and extending over the Barents, Kara and Laptev Seas, and 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above average over the East Siberian, Chukchi, and Beaufort Seas (Figure 2b).

May 2017 compared to previous years

monthly_ice_05_NH_v2.1

Figure 3. Monthly May ice extent for 1979 to 2017 shows a decline of 2.5 percent per decade.

Credit: National Snow and Ice Data Center
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The linear rate of decline for May is 33,900 square kilometers (13,100 square miles) per year, or 2.5 percent per decade.

Low ice in the Chukchi Sea

Fig. 4a. This map shows sea ice concentration in percent coverage for the Alaska area on May 22, 2017.

Credit: NOAA National Weather Service Alaska Sea Ice Program
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Figure 2d.

Figure 4b. The plot shows daily May sea ice extent, in square kilometers, in the Chukchi Sea region for 2012 to 2017.

Credit: J. Stroeve/ NSIDC
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Figure 4c. The graph shows cumulative temperature departures from average for each year, in degrees Fahrenheit, for Barrow, Alaska from 1921 to May 2017.

Credit: Blake Moore, Alaska Climate Research Center
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Notably, sea ice within the Chukchi Sea retreated earlier than seen at any other time in the satellite data record. By the third week in May, open water extended all the way to Barrow, Alaska (Figure 4a). Figure 4b shows daily ice extent for May from 2012 onward in the Chuckchi Sea. The rapid retreat in 2017 stands out. A recent report by the National Oceanographic Atmospheric Administration (NOAA) indicates that the amount of open water north of 68o N at this time of year is unprecedented.

Part of the explanation for earlier open water formation in the Chukchi Sea is the unusually high air temperatures in that region during the previous winter. It is instructive to look at the cumulative temperature departure from average for Barrow, Alaska (Figure 4c). From 1921 until about 1989, conditions at Barrow actually got progressively cooler. However, since that time, temperatures have markedly increased.

Consistent with warm conditions, extensive open water in the Chukchi Sea region persisted into December; the delayed ice growth potentially led to thinner ice than usual in spring. In addition, strong winds from the north occurred for a few days at the end of March and early April, pushing ice southward in the Bering Sea, breaking up the ice in the Chukchi Sea, and even flushing some ice out through the Bering Strait. At the same time further east near Barrow, winds helped to push ice away from the coast. Based on recent work by NSIDC and the University of Washington, the pattern of spring sea ice retreat also suggests a role of strong oceanic heat inflow to the Chukchi Sea via Bering Strait.

Impacts of low Chukchi Sea on Alaskan communities

The ARCUS Sea Ice for Walrus Outlook (SIWO) provides weekly reports from April to June on sea ice conditions in the northern Bering Sea and southern Chukchi Sea regions of Alaska to support subsistence hunters and coastal communities. While the reports are not intended for operational planning or navigation, they provide detailed ice and weather observations for the region, some made by local community members, others from operational forecast centers. The most recent update on June 2nd discusses the continued rapid deterioration of sea ice between Wales and Shishmaref, Alaska. Nearly ice-free conditions around Nome, Alaska reflect warmer waters from the Bering Sea moving into the region. Some sea ice remains attached to the shore along the northeast coast of St. Lawrence Island, but the Bering Sea is essentially ice free. Prime walrus hunting for these communities is typically in May. However, when the ice retreats early, the walrus go with it, reducing the number of walrus the local communities can hunt.

Sea ice data and analysis tools

NSIDC has released a new set of tools for sea ice analysis and visualization. In addition to Charctic, our interactive sea ice extent graph, the new Sea Ice Data and Analysis Tools page provides access to Arctic and Antarctic sea ice data organized in seven different data workbooks, updated daily or monthly. Animations of September Arctic and Antarctic month average sea ice and concentrations may also be accessed from this page.

Further Reading

Serreze, M.C., Crawford, A., Stroeve, J. C., Barrett, A.P. and Woodgate, R.A. 2016.  Variability, trends and predictability of seasonal sea ice retreat and advance in the Chukchi Sea.  Journal of Geophysical Research, 121, doi:10.1002/2016JC011977.

 

 

Warm Arctic, cool continents

Arctic sea ice extent for April 2017 tied with April 2016 for the lowest in the satellite record for the month. Warm weather conditions and lower-than-average sea ice extent prevailed over the Pacific side of the Arctic, while relatively cool conditions were the rule in northern Europe and eastern North America. In the Southern Hemisphere, Antarctic sea ice extent remained lower than average.

Overview of conditions

Figure 1. Arctic sea ice extent for April 2017 was 13.83 million square kilometers (5.34 million square miles). The magenta line shows the 1981 to 2010 average extent for that month.

Figure 1. Arctic sea ice extent for April 2017 was 13.83 million square kilometers (5.34 million square miles). The magenta line shows the 1981 to 2010 average extent for that month. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Arctic sea ice extent for April 2017 averaged 13.83 million square kilometers (5.34 million square miles), and tied with April 2016 for the lowest April extent in the 38-year satellite record. The April 2017 extent is 1.02 million square kilometers (394,000 square miles) below the April 1981 to 2010 long-term average. The largest reductions in ice extent through the month occurred on the Pacific side of the Arctic, within the Bering Sea and the Sea of Okhotsk. Little change in extent occurred in the Atlantic sector of the Arctic.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of May 2, 2017, along with daily ice extent data for four previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, and 2013 in purple, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data.

Figure 2a. The graph above shows Arctic sea ice extent as of May 2, 2017, along with daily ice extent data for five previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, and 2013 in purple, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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Figure 2b. These figures show April 2017 Arctic air temperature difference at the 925 hPa level (about 2,500 feet above sea level) in degrees Celsius (left) and sea level pressure (right). Yellows and reds indicate higher than average temperatures and pressure; blues and purples indicate lower than average temperatures and pressure.

Figure 2b. These figures show April 2017 differences from average for Arctic air temperatures at the 925 hPa level (about 2,500 feet above sea level) in degrees Celsius (left) and for sea level pressure (right). Yellows and reds indicate higher than average temperatures and pressure; blues and purples indicate lower than average temperatures and pressure.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division
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Figure 2c. These maps show Arctic sea ice motion for April 13 to 15, 2017, which is representative of the general pattern seen throughout the month. Black arrows represent sea ice drift. The purple arrows represent "filled" values, data gaps that have been interpolated from surrounding data.

Figure 2c. These maps show Arctic sea ice motion for April 13 to 15, 2017, which is representative of the general pattern seen throughout the month. Black arrows represent sea ice drift. The purple arrows represent “filled” values, data gaps that have been interpolated from surrounding data.

Credit: EUMETSAT
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The decline in ice extent through the month was fairly steady, at a rate similar to what was observed over the previous two Aprils (2016 and 2015). Throughout the month, sea ice extent was either at daily record lows for the period of satellite observations, or within 100,000 square kilometers (~38,600 square miles) of record low values. At the end of the month, extent was below average in the Barents Sea, the Sea of Okhotsk, and the western Bering Sea, similar to the pattern seen in March. Despite fairly warm conditions, sea ice extent was slightly above average in Baffin Bay.

Unusually warm conditions were observed across the Pacific side of the Arctic Ocean, with temperatures at the 925 hPa level (about 2,500 feet above sea level) north of the Bering Strait ranging from 6 to 8 degrees Celsius (11 to 14 degrees Fahrenheit) above the 1981 to 2010 average. Western Alaska and easternmost Siberia also saw warm conditions. However, below average temperatures ruled across a broad swath of northern Canada. Of particular note, cooler-than-average conditions also prevailed over Greenland, leading to relatively little surface melting on the ice sheet in April (unlike the preceding two years).

The overall temperature pattern is consistent with the average sea level pressure pattern for the month, which had large areas of low and higher-than-average pressure in the Eastern and Western Hemispheres, respectively. This pattern produces a cross-Arctic airflow, with southerly winds from the Bering Sea blowing into the Chukchi Sea and central Arctic, and cool winds blowing from the north over Scandinavia and other areas of northern Europe. This cross-Arctic wind pattern is also evident in the sea ice motion field for April 2017. Sea ice motion is determined by tracking patterns in the sea ice in both visible imagery and in passive microwave data from satellites.

April 2017 compared to previous years

Figure 3a. Monthly April ice extent for 1979 to 2017 shows a decline of 2.6 percent per decade.

Figure 3a. Monthly April ice extent for 1979 to 2017 shows a decline of 2.6 percent per decade.

Credit: National Snow and Ice Data Center
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Figure 3b. This shows April 2017 Arctic sea ice concentration anomalies (left) and Arctic sea ice concentration trends (right).

Figure 3b. These images show April 2017 Arctic sea ice concentration anomalies (left) and Arctic sea ice concentration trends (right). Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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The linear rate of decline for April is 38,000 square kilometers (15,000 square miles) per year, or 2.6 percent per decade.

Declining ice extent in the Barents Sea, Sea of Okhotsk, and off the coast of southeastern Greenland is a part of the long-term pattern of sea ice decline. Below-average ice extent in the western Bering Sea has to date not been a part of the long-term trend for April.

A report from the field

Figure 4. This photo shows broken up sea ice and some multi-year floes at Alert, on the northern tip of Ellesmere Island, Canada. A researcher and a Twin Otter aircraft are obscured in the background.

Figure 4. This photo shows broken up sea ice and some multi-year floes at Alert, on the northern tip of Ellesmere Island, Canada on April 2017. A researcher and a Twin Otter aircraft are obscured in the background.

Credit: J. Stroeve/NSIDC
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NSIDC scientist Julienne Stroeve continued her Arctic field work into early April, moving from Cambridge Bay, Canada to Alert in Ellesmere Island. In Alert, Stroeve focused on sampling ice thickness and snow pack characteristics along a CryoSat-2 flight track within the Lincoln Sea. This is an area between northernmost Greenland and Ellesmere Island where thick, old ice remains. The scientists flew by Twin Otter each day, out onto the sea ice between latitudes 83°N and 87.1°N. The field campaign was also supported by an aircraft from the British Antarctic Survey carrying a Ka band radar, LiDAR, and a broadband radiometer. A NASA Operation IceBridge flight also flew over the same track.

The group noted that the ice was unusually broken up and reduced to rubble, with few large multi-year floes, forcing the pilots to land on refrozen leads that at times were only 70 centimeters (28 inches) thick. Pilots remarked that they had never seen the ice look like this. Preliminary estimates suggest mean thicknesses ranging from 2 to 3.4 meters (6.6 to 11 feet), with the thickest ice found between an ice bridge in the Lincoln Sea and mobile pack ice to the north. Modal thickness, a representation of thermodynamically-grown level ice, ranged between 1.8 and 2.9 meters (6 and 10 feet), including 0.25 to 0.4 meters (10 to 16 inches) of snow. Second- and first-year modal ice thicknesses ranged between 1.8 and 1.9 meters (6 and 6.2 feet), about 0.2 meters (8 inches) thinner than previous airborne measurements indicated. More details can be found at the European Space Agency’s Campaigns at Work blog.

Arctic sea ice age

Figure 5. These maps shows 2016 (top left) and 2017 (top right) Arctic sea ice age for the end of March and the time series of percent coverage for the Arctic Ocean (bottom).

Figure 5. These maps shows 2016 (top left) and 2017 (top right) Arctic sea ice age for the end of March and the time series of percent coverage for the Arctic Ocean (bottom).

Credit: National Snow and Ice Data Center, courtesy M. Tschudi, C. Fowler, J. Maslanik, R. Stewart/University of Colorado Boulder; W. Meier/NASA Cryospheric Sciences
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Sea ice age is a proxy for ice thickness, with older ice generally meaning thicker ice. Though ice can pile up into rubble fields when the motion of the ice pushes up against the coast or thicker ice, level ice generally increases in thickness as it ages through more winter freeze cycles. Thus, ice age is a reasonable indicator of the sea ice thickness.

At the end of March, ice age data show only a small remaining coverage of old (5+ years) ice. Since 2011, the oldest ice has comprised less than 5 percent of the total ice cover. During the mid-1980s, such ice made up nearly a third of the ice.

The next oldest ice category, four-year-old ice has also dropped from about 8 to 10 percent to less than 5 percent. The coverage of intermediate age ice categories (2- and 3-year-old ice) has stayed fairly consistent through time. The oldest ice has essentially been replaced by first-year ice (ice that has formed since the previous September). First-year-ice has risen from 35 to 40 percent of the Arctic Ocean’s ice cover during the mid-1980s to about 70 percent now.

Comparison of March 2016 conditions to this year shows a similar percentage coverage for the different ice ages. However, the spatial distribution is different. In March 2016, bands of the oldest ice extended through the Beaufort Sea and into the Chukchi, with scattered patches north of the Canadian Archipelago and Greenland. This year, the oldest ice is consolidated against the coast of Greenland and the archipelago except for a short arm extending north to the region around the pole. Most of the third year ice is between Fram Strait and the pole, which means it is likely to exit the Arctic Ocean during the coming months.

Antarctic ice extent low, but not lowest

Figure 6. The graph above shows Antarctic sea ice extent as of May 2, 2017, along with daily ice extent data for four previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, and 2013 in purple, and 2012 in dashed brown. The 1981 to 2010 median is in dark gray. The gray areas around the median line show the interquartile and interdecile ranges of the data.

Figure 6. The graph above shows Antarctic sea ice extent as of May 2, 2017, along with daily ice extent data for four previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in dashed brown, and 2013 in purple. 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

Antarctic sea ice grew at a slightly faster-than average pace in April, but was still setting daily record lows until about April 10, after which extent rose above the 1980 ice extent. The April 2017 sea ice extent is lower than average in the Amundsen Sea and slightly lower than average in the Ross Sea and easternmost Weddell Sea. However, an area of above average extent is present in the north-central Weddell. Temperatures on the continent were above average over West Antarctica and western Wilkes Land, and considerably below average over the central Weddell sea.

Another record, but a somewhat cooler Arctic Ocean

Arctic sea ice extent for March 2017 was the lowest in the satellite record for the month. The decline in ice extent has been uneven since the seasonal maximum was reached on March 7, 2017, with a modest period of expansion towards the end of the month.

Overview of conditions

extent map

Figure 1. Arctic sea ice extent for March 2017 was 14.43 million square kilometers (5.57 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 March 2017 averaged 14.43 million square kilometers (5.57 million square miles), the lowest March extent in the 38-year satellite record. This is only 60,000 square kilometers (23,000 square miles) below March 2015, the previous lowest March extent, and 1.17 million square kilometers (452,000 square miles) below the March 1981 to 2010 long-term average. This month continues the record low conditions seen since October 2016.

Conditions in context

timeseries graph

Figure 2a. The graph above shows Arctic sea ice extent as of April 9, 2017, along with daily ice extent data for five previous years. 2017 to 2016 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, 2012 to 2013 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

air temperature plot

Figure 2b. The plot shows Arctic air temperature differences at the 925 hPa level (about 2,500 feet above sea level) in degrees Celsius for March 2017. Yellows and reds indicate temperatures higher than the 1981 to 2010 average; blues and purples indicate temperatures lower than the 1981 to 2010 average.

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

sea level pressure plot

Figure 2c. The plot shows Arctic sea level pressure (in millibars) for March 2017 expressed as departures from average conditions. The dominant feature is a large area of below average pressure covering most of the Arctic Ocean.

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

The decline in sea ice extent following the March 2017 seasonal maximum was interrupted by a brief period of expansion from about March 11 to 15, a decline extending through about March 26, then another period of growth through the end of the month into early April. On April 4th, the extent was greater than on the same day in 2016. This type of behavior is not unusual for this time of year when declines in extent in warmer, lower latitudes can be countered by periods of expansion in the still-cold higher latitudes. Shifts in wind patterns also lead to variability. Regions that experienced slight ice advance were at the end of the month in the Barents Sea and in the Bering Sea. Nevertheless, by early April, extent remained below average in the Barents Sea and in the Sea of Okhotsk and the western Bering Sea. Interestingly, ice extended further south than usual in the eastern Bering Sea.

March saw continued warmth over the Arctic Ocean. The warmest conditions for March 2017 as compared to average were over Siberia. While temperatures were still well above average along the Russian coastal seas (6 to 7 degrees Celsius, or 11 to 13 degrees Fahrenheit), those over the northern North Atlantic and the Canadian Arctic Archipelago were near average.

The dominant feature of the sea level pressure field for March 2017 was an area of below average pressure covering most of the Arctic Ocean. Locally, pressures were more than 15 millibars below the 1981 to 2010 average. This pattern points to a continuation of the stormy conditions that prevailed over the past winter and is broadly consistent with the positive phase of the Arctic Oscillation, a large-scale mode of climate variability. When the Arctic Oscillation is in its positive phase, sea level pressure is below average over the Arctic Ocean. The Arctic Oscillation has generally been in a positive phase since December. The unusually high Siberian temperatures for March 2017 are consistent with persistent winds from the south and east along the southern side of the low pressure.

March 2017 compared to previous years

trend graph

Figure 3. Monthly March ice extent for 1979 to 2017 shows a decline of 2.74 percent per decade.

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

The linear rate of decline for March is 42,700 square kilometers (16,500 square miles) per year, or 2.74 percent per decade.

Report from the field

research photo

Figure 4. The team prepares to measure snow thickness over sea ice in Cambridge Bay, Canada on April 5, 2017, during an AltiKa field validation campaign. NSIDC researcher Andrew Barrett is in a red jacket; Julienne Stroeve holds a magna probe.

Credit: Isobel Lawrence
High-resolution image

As of the publication of this post, NSIDC scientists Julienne Stroeve and Andrew Barrett are in Cambridge Bay, Canada on a satellite validation campaign. Efforts focus on ground measurements of snow depth over sea ice, ice thickness, and snow structure in order to validate the joint French/Indian AltiKa Ka band radar altimeter. Coincident aircraft Ka band and LiDAR measurements allow researchers to connect measurements on the ground with those made by the satellite. Air temperatures have ranged from -20 to -5 degrees Celsius (-4 to 23 degrees Fahrenheit), with wind chills from -40 to -20 degrees Celsius (-40 to -4 degrees Fahrenheit). Dr. Stroeve will then join another field campaign operating out of Alert, Canada for further validation of AltiKa and CryoSat2 over the Lincoln Sea.

Arctic sea ice thickness

sea ice volume plot

Figure 5. The graph shows sea ice volume from the PIOMAS model/observations for each year from 2010 through March 2017, and the 1979 to 2016 average (black line) and one (dark gray) and two (light gray) standard deviation ranges.

Credit: NSIDC courtesy University of Washington Polar Science Center
High-resolution image

A key early indicator for the upcoming melt season is the thickness of the sea ice. An assessment of available information suggests a fairly thin ice cover, not surprising given the warm temperatures over much of the Arctic Ocean during the winter.

Satellite data from the European Space Agency (ESA) CryoSat-2 radar altimeter, which is processed into sea ice thickness estimates at the University College London’s Center for Polar Observing and Modeling (CPOM) indicates ice along much of the Siberian coast with thicknesses of 1.5 to 2.0 meters (4.9 to 6.6 feet) or less. This is not atypical for seasonal ice; however this band of <2.0 meters of ice covers a much larger region and extends much farther north than it used to—well north of 80 degrees N latitude on the Atlantic side of the Arctic. NASA’s Operation IceBridge has also been collecting data over the past month. That data will not be available for a few weeks; a key focus of some flights has involved collaboration with ESA to collect coincident data with CryoSat-2 to help validate the satellite estimates.

Another way to estimate thickness and total ice volume is with a combination of observations and a model, which is done by the University of Washington Polar Science Center’s University of Washington Polar Science Center’s Pan-Arctic Ice Ocean Modeling and Assimilation System (PIOMAS). The model uses observed sea ice concentration fields to constrain the model and estimates thickness and total volume via physical simulations in the model. It shows that sea ice volume has been at record low levels throughout 2017 so far (Figure 5).

Sea ice loss and Atlantic layer heat

For many years, scientists have pondered how much of the sharp decline in summer sea ice extent and volume is due to “top down” forcing—a warmer atmosphere leading to more summer melt and less winter growth, versus “bottom up” forcing, in which ocean heat is brought to bear on the underside of the ice. There is a great deal of heat in the Arctic Ocean from waters that are imported from the Atlantic. As fairly warm and salty Atlantic water enters the Arctic Ocean it dives underneath the relatively fresh Arctic Ocean surface layer. Because the fresh surface layer has a fairly low density, the vertical structure of the Arctic Ocean is very stable. As such, it is hard to mix this Atlantic heat upwards to melt ice or keep it from forming in the first place. However, new work by an international team led by Igor Polyakov of the University of Alaska Fairbanks provides strong evidence that Atlantic layer heat is now playing a prominent role in reducing winter ice formation in the Eurasian Basin, which is manifested as more summer ice loss. According to their analysis, the ice loss due to the influence of Atlantic layer heat is comparable in magnitude to the top down forcing by the atmosphere.

Antarctic ice extent low, but on the rise

antarctic timeseries plot

Figure 6. The graph above shows Antarctic sea ice extent as of April 9, 2017, along with daily ice extent data for four previous years. 2017 is shown in blue, 2016 in green, 2015 in orange, 2014 in brown, and 2013 in purple. 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

Following the record-low seasonal sea ice minimum, Antarctic sea ice extent has sharply risen, but extent is still far below average, and set daily record low values throughout the month of March. Regionally, sea ice recovered to near average conditions in the Weddell Sea and around much of the coast of East Antarctica. The primary region of below average extent was in the Ross, Amundsen, and Bellingshausen Sea regions, as has been the case throughout the spring and summer. This appears to be related to warmer-than-average sea surface temperatures.

Additional reading

Polyakov, I., A.V. Pnyushkov, M.B. Alkire, I.M. Ashik, T.M. Baumann, E.C. Carmack and 10 others. 2017. Greater role for Atlantic inflows on sea-ice loss in the Eurasian Basin of the Arctic Ocean. Science, doi:10.1126/science.aai8204.

 

 

Arctic sea ice maximum at record low for third straight year

Arctic sea ice appears to have reached its annual maximum extent on March 7. This is the lowest maximum in the 38-year satellite record. NSIDC will post a detailed analysis of the 2016 to 2017 winter sea ice conditions in our regular monthly post in early April.

Overview of conditions

Figure 1. Arctic sea ice extent for March 7, 2017 was 14.42 million square kilometers (5.57 million square miles). The orange line shows the 1981 to 2010 median extent for that day.

Figure 1. Arctic sea ice extent for March 7, 2017 was 14.42 million square kilometers (5.57 million square miles). The orange line shows the 1981 to 2010 median extent for that day. Sea Ice Index data. About the data

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

On March 7, 2017, Arctic sea ice likely reached its maximum extent for the year, at 14.42 million square kilometers (5.57 million square miles), the lowest in the 38-year satellite record. This year’s maximum extent is 1.22 million square kilometers (471,000 square miles) below the 1981 to 2010 average maximum of 15.64 million square kilometers (6.04 million square miles) and 97,000 square kilometers (37,000 square miles) below the previous lowest maximum that occurred on February 25, 2015. This year’s maximum is 100,000 square kilometers (39,000 square miles) below the 2016 maximum, which is now third lowest. (In 2016, we reported that year’s maximum as the lowest and 2015 the second lowest. An update to the Sea Ice Index last summer has changed our numbers slightly.)

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of March 20, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. 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.

Figure 2a. The graph above shows Arctic sea ice extent as of March 20, 2017, along with daily ice extent data for five previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, 2012 to 2013 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. The plot shows Arctic air temperature differences at the 925 hPa level in degrees Celsius from October 1, 2016 to February 28, 2017. Yellows and reds indicate temperatures higher than the 1981 to 2010 average; blues and purples indicate temperatures lower than the 1981 to 2010 average.

Figure 2b. The plot shows Arctic air temperature differences at the 925 hPa level (about 2,500 feet above sea level) in degrees Celsius from October 1, 2016 to February 28, 2017. Yellows and reds indicate temperatures higher than the 1981 to 2010 average; blues and purples indicate temperatures lower than the 1981 to 2010 average.

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

It was a very warm autumn and winter. Air temperatures at the 925 hPa level (about 2,500 feet above sea level) over the five months spanning October 2016 through February 2017 were more than 2.5 degrees Celsius (4.5 degrees Fahrenheit) above average over the entire Arctic Ocean, and greater than 5 degrees Celsius (9 degrees Fahrenheit) above average over large parts of the northern Chukchi and Barents Seas. These overall warm conditions were punctuated by a series of extreme heat waves over the Arctic Ocean.

Data from the European Space Agency’s CryoSat-2 satellite indicate that this winter’s ice cover may be only slightly thinner than that observed at this time of year for the past four years. However, an ice-ocean model at the University of Washington (PIOMAS) that incorporates observed weather conditions suggests the volume of ice in the Arctic is unusually low.

The Antarctic minimum

Figure 3. Antarctic sea ice extent for March 3, 2017 was 2.11 million square kilometers (813,000 million square miles). The orange line shows the 1981 to 2010 average extent for that day.

Figure 3. Antarctic sea ice extent for March 3, 2017 was 2.11 million square kilometers (815,000 square miles). The orange line shows the 1981 to 2010 median extent for that day. Sea Ice Index data. About the data

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

In the Southern Hemisphere, sea ice likely reached its minimum extent for the year on March 3, at 2.11 million square kilometers (815,000 square miles). This year’s minimum extent was the lowest in the satellite record, continuing a period of satellite-era record low daily extents that began in early November. However, the Antarctic system has been highly variable. As recently as 2015, Antarctic sea ice set record high daily extents, and in September 2014 reached a record high winter maximum.

The Antarctic minimum extent is 740,000 square kilometers (286,000 square miles) below the 1981 to 2010 average minimum of 2.85 million square kilometers (1.10 million square miles) and 184,000 square kilometers (71,000 square miles) below the previous lowest minimum that occurred on February 27, 1997.

Antarctic air temperatures during the autumn and winter were above average, but less so than in the Arctic. Air temperatures at the 925 hPa level (about 2,500 feet above sea level) near the sea ice edge have been about 1 to 2.5 degrees Celsius (2 to 4.5 degrees Fahrenheit) above the 1981 to 2010 average.

Final analysis pending

At the beginning of April, NSIDC scientists will release a full analysis of winter conditions, along with monthly data for March. For more information about the maximum extent and what it means, see the NSIDC Icelights post, the Arctic sea ice maximum.

Correction

On March 27, 2017, we made corrections to clarify the second paragraph under Conditions in context. The paragraph originally read:

Data from the European Space Agency’s CryoSat-2 satellite indicate that this winter’s ice cover is slightly thinner compared to the past four years. An ice-ocean model at the University of Washington that incorporates observed weather conditions suggests the volume of ice in the Arctic is unusually low for this time of year.

Another warm month in the Arctic

High air temperatures observed over the Barents and Kara Seas for much of this past winter moderated in February. Overall, the Arctic remained warmer than average and sea ice extent remained at record low levels.

Overview of conditions

Figure 1. Arctic sea ice extent for February 2017 was 14.28 million square kilometers (5.51 million square miles). The magenta line shows the 1981 to 2010 median 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 2017 was 14.28 million square kilometers (5.51 million square miles). The magenta line shows the 1981 to 2010 median extent for the month. Sea Ice Index data. About the data

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

Arctic sea ice extent for February 2017 averaged 14.28 million square kilometers (5.51 million square miles), the lowest February extent in the 38-year satellite record. This is 40,000 square kilometers (15,400 square miles) below February 2016, the previous lowest extent for the month, and 1.18 million square kilometers (455,600 square miles) below the February 1981 to 2010 long term average.

Ice extent increased at varying rates, with faster growth during the first and third weeks, and slower growth during the second and fourth weeks. Most of the ice growth in February occurred in the Bering Sea, though extent in the Bering remained below average by the end of the month. Sea ice extent in the Sea of Okhotsk substantially decreased mid-month before rebounding to almost typical levels at the end of the month. Overall, however, the ice retreated in this region. Extent in the Barents and Kara Seas remained low through the month as is has all season, with little change in the ice edge location.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of March 5, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. 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. About the data||Credit: National Snow and Ice Data Center|High-resolution image

Figure 2a. The graph above shows Arctic sea ice extent as of March 5, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. 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. About the data

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

Figure 2b. The plot shows Arctic air temperature differences at the 925 hPa level in degrees Celsius for February 2017. Yellows and reds indicate temperatures higher than the 1981 to 2010 average; blues and purples indicate temperatures lower than the 1981 to 2010 average.||Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division| High-resolution image

Figure 2b. The plot shows Arctic air temperature differences at the 925 hPa level in degrees Celsius for February 2017. Yellows and reds indicate temperatures higher than the 1981 to 2010 average; blues and purples indicate temperatures lower than the 1981 to 2010 average.

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

Air temperatures at the 925 hPa level (approximately 2,500 feet above sea level) remained 2 to 5 degrees Celsius (4 to 9 degrees Fahrenheit) above average over the Arctic Ocean. The high air temperatures observed over the Barents and Kara Seas for much of this past winter moderated in February. February air temperatures over the Barents Sea ranged between 4 to 5 degrees Celsius (8 to 9 degrees Fahrenheit) above average, compared to 7 degrees Celsius (13 degrees Fahrenheit) above average in January. Recall that these January temperature extremes were associated with a series of strong cyclones entering the Arctic Ocean from the North Atlantic, drawing in warm air. Sea level pressure in February was nevertheless lower than average over much of the Arctic Ocean. Sea level pressure was higher than average over the Bering Sea and just north of Scandinavia.

February 2017 compared to previous years

Figure 3. Monthly February ice extent for 1979 to 2017 shows a decline of 3 percent per decade.||Credit: National Snow and Ice Data Center| High-resolution image

Figure 3. Monthly February ice extent for 1979 to 2017 shows a decline of 3 percent per decade.

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

The linear rate of decline for February is 46,900 square kilometers (18,100 square miles) per year, or 3 percent per decade.

Antarctic minimum extent

Figure 4a. The graph above shows Antarctic sea ice extent as of March 5, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. 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 4a. The graph above shows Antarctic sea ice extent as of March 5, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. 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 4b. This graph shows monthly ice extent for February plotted as a time series of percent differences with respect to the average over the period 1981 through 2010. The dotted gray line shows the linear trend. Sea Ice Index data. About the data||Credit: National Snow and Ice Data Center|High-resolution image

Figure 4b. This graph shows monthly ice extent for February, plotted as a time series of percent differences from the 1981 to 2010 average. The dotted gray line shows the linear trend. Sea Ice Index data. About the data

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

Antarctic sea ice is nearing its annual minimum extent and continues to track at record low levels for this time of year. On February 13, Antarctic sea ice extent dropped to 2.29 million square kilometers (884,000 square miles), setting a record lowest extent in the satellite era. The previous lowest extent occurred on February 27, 1997. By the end of February, extent had dropped even further to 2.13 million square kilometers (822,400 square miles). The record lows are not surprising, given Antarctic sea ice extent’s high variability. Just a few years back, extent in the region set record highs (Figure 4b).

Sea ice extent was particularly low in the Amundsen Sea, which remained nearly ice-free throughout February. Typically, sea ice in February extends at least a couple hundred kilometers along the entire coastline of the Amundsen. Near-average ice extent persisted in the Weddell Sea and in several sectors along the East Antarctic coast.

Continuity of the sea ice record

Figure 5. This chart shows the lifespans of current and future orbiting passive microwave sensors. ||Credit: Walt Meier, NASA| High-resolution image

Figure 5. This chart shows the lifespans of current and expected future orbiting passive microwave sensors.

Credit: W. Meier, NASA Goddard Space Flight Center Cryospheric Sciences Laboratory
High-resolution image

As noted last year, the sensor that NSIDC had been using for sea ice extent, the Special Sensor Microwave Imager and Sounder (SSMIS) on the Defense Meteorological Satellite Program (DMSP) F17 satellite, started to malfunction. In response, NSIDC switched to the SSMIS on the newer F18 satellite. Later, F17 recovered to normal function, though it recently started to malfunction again.

The DMSP series of sensors have been a stalwart of the sea ice extent time series, providing a continuous record since 1987. Connecting this to data from the earlier Scanning Multichannel Microwave Radiometer (SMMR) results in a continuous record starting in 1979 of high quality and consistency. However, with the issues of F17 and last year’s loss of the newest sensor, F19, grave concerns have arisen about the long-term continuity of the passive microwave sea ice record. Only two DMSP sensors are currently fully capable for sea ice observations: F18 and the older F16; these two sensors have been operating for over 7 and 13 years respectively, well beyond their nominal 5-year lifetimes.

The only other similar sensor currently operating is the Japan Aerospace Exploration Agency (JAXA) Advanced Microwave Scanning Radiometer 2 (AMSR2), which is approaching its 5-year design lifetime in May 2017. NSIDC is now evaluating AMSR2 data for integration into the sea ice data record if needed. Future satellite missions with passive microwave sensors are either planned or proposed by the U.S., JAXA, and ESA, but it is unlikely that a successor to the DMSP series and AMSR2 will be operational before 2022. This presents a growing risk of a gap in the sea ice extent record. Should such a gap occur, NSIDC and NASA would seek to fill the gap as much as possible with other types of sensors (e.g., visible or infrared sensors).

2017 ushers in record low extent

Record low daily Arctic ice extents continued through most of January 2017, a pattern that started last October. Extent during late January remained low in the Kara, Barents and Bering Seas. Southern Hemisphere extent also tracked at record low levels for January; globally, sea ice cover remains at record low levels.

Overview of conditions

extent map

Figure 1. Arctic sea ice extent for January 2017 was 13.38 million square kilometers (5.17 million square miles). The magenta line shows the 1981 to 2010 median 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 2017 averaged 13.38 million square kilometers (5.17 million square miles), the lowest January extent in the 38-year satellite record. This is 260,000 square kilometers (100,000 square miles) below January 2016, the previous lowest January extent, and 1.26 million square kilometers (487,000 square miles) below the January 1981 to 2010 long-term average.

Ice growth stalled during the second week of the month, and the ice edge retreated within the Kara and Barents Seas, and within the Sea of Okhotsk. After January 16, extent increased at a more rapid pace, but the rate of ice growth was still below average for January as a whole. For a few days towards the end of the month, the extent was slightly greater than recorded in 2006, a year which also saw many record low days in January, but by the 30th it was tracking below 2006. Through most of January the ice edge remained north of the Svalbard Archipelago, largely due to the inflow of warm Atlantic water along the western part of the archipelago. However, by the end of January, some ice was found to the northeast and northwest of Svalbard. At the end of January, ice extent remained well below average within the Kara, Barents, and Bering Seas.

Conditions in context

time series graph

Figure 2a. The graph above shows Arctic sea ice extent as of February 5, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. The 1981 to 2010 average 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 plot shows Arctic air temperature difference from average, in degrees Celsius, for January 2017.

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

January air temperatures at the 925 hPa level (approximately 2,500 feet above sea level) were above average over nearly all of the Arctic Ocean, continuing the pattern that started last autumn (Figure 2b). Air temperatures were more than 5 degrees Celsius (9 degrees Fahrenheit) above the 1981 to 2010 average over the northern Barents Sea and as much as 4 degrees Celsius (7 degrees Fahrenheit) above average in the northern Chukchi and East Siberian Seas. It was also unusually warm over northwestern Canada. Cooler than average conditions (up to 3 degrees Celsius, or 5 degrees Fahrenheit below average) prevailed over the northwest part of Russia and the northeast coast of Greenland.

Atmospheric circulation over the Arctic during the first three weeks of January was characterized by a broad area of below average sea level pressure extending over almost the entire Arctic Ocean. Higher-than-average sea level pressure dominated over the Gulf of Alaska and the North Atlantic Ocean south of Iceland. This set up warm southerly winds from both the northern North Atlantic and the Bering Strait areas, helping to explain the high January air temperatures over the Arctic Ocean. According to the analysis of NASA scientist Richard Cullather, the winter of 2015 to 2016 was the warmest ever recorded in the Arctic in the satellite data record. Whether the winter of 2016 to 2017 will end up warmer remains to be seen; conditions are typically highly variable. For example, during the last week of January, the area of low pressure shifted towards the Siberian side of the Arctic. In the northern Laptev Sea, pressures fell to more than 20 hPa below the 1981 to 2010 average. This was associated with a shift towards cooler conditions over the Arctic Ocean, which may explain why ice extent towards the end of the month rose above levels recorded in 2006.

January 2017 compared to previous years

trend graph

Figure 3. Monthly January ice extent for 1979 to 2017 shows a decline of 3.2 percent per decade.

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

Through 2017, the linear rate of decline for January is 47,400 square kilometers (18,300 square miles) per year, or 3.2 percent per decade.

Amundsen Sea nearly free of ice

S_daily_extent_hires

Figure 4. Antarctic sea ice extent for February 5, 2017 shows the Amundsen Sea nearly free of ice. The orange line shows the 1981 to 2010 median extent for that day. Sea Ice Index data. About the data

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

Extent is tracking at records low levels in the Southern Hemisphere, where it is currently summer. As shown in this plot for February 5, this is primarily due to low ice extent within the Amundsen Sea, where only a few scattered patches of ice remain. By contrast, extent in the Weddell Sea is now only slightly below average. This pattern is consistent with persistent above average air temperatures off western Antarctica.

Further reading

Cullather, R. I., Y.-K. Lim, L. N. Boisvert, L. Brucker, J. N. Lee, and S. M. J. Nowicki. 2016. Analysis of the warmest Arctic winter, 2015-2016. Geophysical Research Letters,43, doi:10.1002/2016GL071228.

Low sea ice extent continues in both poles

Sea ice in the Arctic and the Antarctic set record low extents every day in December, continuing the pattern that began in November. Warm atmospheric conditions persisted over the Arctic Ocean, notably in the far northern Atlantic and the northern Bering Sea. Air temperatures near the Antarctic sea ice edge were near average. For the year 2016, sea ice extent in both polar regions was at levels well below what is typical of the past several decades.

Overview of conditions

Figure 1. Arctic sea ice extent for December 2016 was 12.10 million square kilometers (4.67 million square miles). The magenta line shows the 1981 to 2010 median extent for that month. The black cross indicates the geographic North Pole.

Figure 1. Arctic sea ice extent for December 2016 was 12.10 million square kilometers (4.67 million square miles). The magenta line shows the 1981 to 2010 median extent for that month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

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

Arctic sea ice extent for December 2016 averaged 12.10 million square kilometers (4.67 million square miles), the second lowest December extent in the satellite record. This is 20,000 square kilometers (7,700 square miles) above December 2010, the lowest December extent, and 1.03 million square kilometers (397,700 square miles) below the December 1981 to 2010 long-term average.

The rate of ice growth for December was 90,000 square kilometers (34,700 square miles) per day. This is faster than the long-term average of 64,100 square kilometers (24,700 square miles) per day. As a result, extent for December was not as far below average as was the case in November. Ice growth for December occurred primarily within the Chukchi Sea, Kara Sea, and Hudson Bay—areas that experienced a late seasonal freeze-up. Compared to the record low for the month set in 2010, sea ice for December 2016 was less extensive in the Kara, Barents, and East Greenland Seas, and more extensive in Baffin and Hudson Bays.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of January 2, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data.

Figure 2a. The graph above shows Arctic sea ice extent as of January 2, 2017, along with daily ice extent data for four previous years. 2016 to 2017 is shown in blue, 2015 to 2016 in green, 2014 to 2015 in orange, 2013 to 2014 in brown, and 2012 to 2013 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

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

Figure 2b. This plot shows air temperature difference from average for December 2016. Air temperatures at the 925 hPa level (approximately 2,500 feet above sea level) were more than 3 degrees Celsius (5 degrees Fahrenheit) above the 1981 to 2010 average over the central Arctic Ocean and northern Barents Sea, and as much as 5 degrees Celsius (9 degrees Fahrenheit) above average over the Chukchi Sea.

Figure 2b. This plot shows air temperature difference from average for December 2016. Air temperatures at the 925 hPa level (approximately 2,500 feet above sea level) were more than 3 degrees Celsius (5 degrees Fahrenheit) above the 1981 to 2010 average over the central Arctic Ocean and northern Barents Sea, and as much as 5 degrees Celsius (9 degrees Fahrenheit) above average over the Chukchi Sea.

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

Air temperatures at the 925 hPa level (approximately 2,500 feet above sea level) were more than 3 degrees Celsius (5 degrees Fahrenheit) above the 1981 to 2010 average over the central Arctic Ocean and northern Barents Sea, and as much as 5 degrees Celsius (9 degrees Fahrenheit) above average over the Chukchi Sea. Repeated warm air intrusions occurred over the Chukchi and Barents Seas, continuing the pattern seen in November.

In contrast, central Russia and northern British Columbia experienced temperatures 3 to 5 degrees Celsius (5 to 9 degrees Fahrenheit) below average (Figure 2b). Atmospheric circulation over the Arctic in December was characterized by a broad area of lower-than-average pressure over Greenland and the North Pole, extending across the Arctic Ocean to eastern Siberia, and another region of low pressure over the Ural Mountains. Higher-than-average pressure dominated Europe and the Gulf of Alaska. This set up the very warm southerly winds from both the northern North Atlantic and the Bering Strait areas, pushing Arctic air temperatures to unusually high levels for brief periods in early December and near Christmas.

December 2016 compared to previous years

Figure 3. Monthly December ice extent for 1979 to 2016 shows a decline of 3.4 percent per decade.

Figure 3. Monthly December ice extent for 1979 to 2016 shows a decline of 3.4 percent per decade.

Credit: National Snow and Ice Data Center
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Through 2016, the linear rate of decline for December is 44,500 square kilometers (17,200 square miles) per year, or 3.4 percent per decade.

While daily extents for December 2016 were at record lows, based on the method employed by NSIDC, the monthly average extent for December 2016 was slightly higher than that recorded for December 2010, the record low December in the satellite record. The monthly average extent for the month of December is higher than the month’s average of daily extents because of the way in which the Sea Ice Index algorithm calculates the monthly extent. The algorithm calculates the monthly average total extent from the monthly average gridded concentration field. Thus, when sea ice is retreating or advancing at a high rate over the course of the month, as was the case for December 2016, the Sea Ice Index monthly average can yield a larger extent than from simply averaging daily extent values. See the Sea Ice Index documentation for further information.

2016 year in review

Figure 4. Arctic temperatures at the 925 hPa level (about 2,500 feet above sea level) over the period January to December of 2016 were above average over nearly the entire Arctic region and especially over the Arctic Ocean. By contrast, air temperatures over the Antarctic region for the same period were above average in some areas, such as the Antarctic Peninsula and near the pole, but below average in others.

Figure 4. Arctic temperatures at the 925 hPa level (about 2,500 feet above sea level) over the period January to December of 2016 were above average over nearly the entire Arctic region and especially over the Arctic Ocean. By contrast, air temperatures over the Antarctic region for the same period were above average in some areas, such as the Antarctic Peninsula and near the pole, but below average in others.

Credit: NSIDC courtesy NOAA/ESRL Physical Sciences Division
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Average annual sea ice extent in both polar regions was low in 2016. Throughout the year, a wave of new record lows were set for both daily and monthly extent. Record low monthly extents were set in the Arctic in January, February, April, May, June, October, and November; and in the Antarctic in November and December.

For the Arctic, the year opened with daily sea ice extent at near record low levels. Sea ice extent in March tied with 2015 for the lowest maximum in the 37-year satellite period. Ice extent was as much as 500,000 square kilometers (193,000 square miles) below any previous year in the record through most of mid-May to early June. However, the pace of decline returned to near-average rates by July, and the end-of-summer minimum sea ice extent, recorded on September 10, eventually tied for second lowest with 2007 (2012 remains the lowest in the satellite time series by more than 600,000 square kilometers or 232,000 square miles).

That September 2016 did not see a new record low is likely due to the unusually stormy atmospheric pattern that set up over the Arctic Ocean in the summer. Storm after storm moved into the central Arctic Ocean, including a pair of very deep low pressure systems in late August. While a stormy pattern will tend to chew up the ice cover, it also spreads the ice out to cover a larger area and typically brings cloudy and, in summer, relatively cool conditions, inhibiting melt. Sometimes these deep lows act to reduce extent by mixing warm ocean waters upwards, but at present there is no compelling evidence that this occurred in 2016.

In October, a pattern of warm air intrusions from the North Atlantic began. This pattern combined with unusually high sea surface temperatures over the Barents and Kara Seas and helped to keep Arctic sea ice extent at low levels for November and December. In the middle of November there was even a several-day period when Arctic sea ice extent decreased. Unusually warm conditions and record low daily sea ice extent levels continued through the end of the year. The unusually high sea ice surface temperatures reflect a shift in ocean circulation, enhancing the import of warm, Atlantic-derived waters into the Arctic Ocean.

In the Southern Hemisphere, overall sea ice extent shifted from near-average over the first half of the year to sharply below average in mid-August. This initiated a period of near-record, and then extreme record low extents that persisted until late in the year. While the Antarctic seasonal sea ice minimum was unremarkable (slightly earlier, and slightly lower, than the 37-year average), the sea ice maximum occurred early (August 31), followed by a period of rapid ice extent decline. By November, extent was more than 2 million square kilometers (772,000 square miles) below the 1981 to 2010 average extent. In combination with the low Arctic sea ice extent for November, this produced a remarkably low global sea ice total.

The cause of the rapid drop in Antarctic sea ice in the second half of 2016 remains elusive. Significant changes in Southern Ocean wind patterns were observed in August, September, and November, but air temperatures and ocean conditions were not highly unusual.

Sea ice cover in Chukchi Sea depends on Bering Strait inflow

Figure 5. This figure shows time series of the Julian dates of seasonal retreat and advance of sea ice in the Chukchi Sea. The trends in retreat and advance (show by the thin solid lines) are related to climate warming. The variations about the trends line are strongly related to variability in the Bering Strait heat inflow. ||Credit: Serreze, M. C., et al. 2016. Journal of Geophysical Research | High-resolution image

Figure 5. This figure shows time series of the Julian dates of seasonal retreat and advance of sea ice in the Chukchi Sea. The trends in retreat and advance (show by the thin solid lines) are related to climate warming. The variations about the trends line are strongly related to variability in the Bering Strait heat inflow.

Credit: Serreze, M. C., et al. 2016. Journal of Geophysical Research

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A recent study by NSIDC scientists Mark Serreze, Julienne Stroeve, and Alexander Crawford, along with University of Washington scientist Rebecca Woodgate, demonstrates strong links between seasonal sea ice retreat and advance in the Chukchi Sea and the inflow of ocean heat into the region through the Bering Strait. The Chukchi Sea region is important as a focus for resource exploration, and vessels transiting the Arctic Ocean must inevitably pass through it. The Chukchi Sea is also part of the seasonal migration route for Bowhead whales that supports subsistence hunting by local indigenous communities.

Serreze and colleagues looked at time series of the date of retreat and advance in which linear trends related to general warming were removed. They found that 68 percent of the variance in the date that ice retreats from the continental shelf break in the Chukchi Sea in spring can be explained by fluctuations in the April through June Bering Strait oceanic heat inflow. The Bering Strait heat inflow data comes from a mooring located within the strait maintained by the University of Washington. They also found that 67 percent of the variance for the date at which ice advances back to the shelf break in autumn and winter can be related to the combined effects of the July through September Bering Strait inflow and the date of ice retreat. When seasonal ice retreat occurs early, low-albedo open water areas are exposed early, which gain a lot of energy from the sun. With more heat in the upper ocean, autumn ice growth is delayed. These relationships with the Bering Strait inflow and ocean heat uptake are superimposed upon the overall trends due to a warming climate. While these relationships lay a path forward to improving seasonal predictions of ice conditions in the region, developing an operational prediction scheme would require more timely acquisition of Bering Strait heat inflow data than is presently possible.

Global sea ice tracking far below average

Figure 6. This time series of daily global sea ice extent (Arctic plus Antarctic) shows global extent tracking below the 1981 to 2010 average. The lower axis of the graph shows month of the year, ticked at the first day of the month

Figure 6a. This time series of daily global sea ice extent (Arctic plus Antarctic) shows global extent tracking below the 1981 to 2010 average. The X axis shows the month of the year, aligned with the first day of the month. Sea Ice Index data.

Credit: NSIDC
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Figure 6b. Waiting for caption. Lorem ipsum. ||Credit: National Snow and Ice Data Center| High-resolution image

Figure 6b. This graph shows daily global sea ice difference from average, relative to the 1981 to 2010 reference period in square kilometers for the satellite record from 1979 through 2016

Credit: National Snow and Ice Data Center
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Figure 6c. Waiting for caption. Lorem ipsum. ||Credit: National Snow and Ice Data Center| High-resolution image

Figure 6c. This graph shows daily sea ice difference from average in units of the standard deviation (based on 1981-2010 variation from the average) for this period.

Credit: National Snow and Ice Data Center
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Global sea ice (Arctic plus Antarctic) continues to track at record low levels in the satellite record, but the deviation from average has moderated compared to what was observed in November. This reflects a December pattern of faster-than-average growth in the Arctic, and slightly slower-than average sea ice extent decline in the Southern Ocean. The gap between the 1981 to 2010 average and the 2016 combined ice extent for December now stands at about 3.0 million square kilometers (1.16 million square miles), down from a peak difference of just over 4 million square kilometers (1.50 million square miles) in mid-November. This globally combined low ice extent is a result of largely separate processes in the two hemispheres.

Changes to our graphics for 2017

 Figure 7. This comparison shows the changes that will be made to NSIDC time series graphs.

Figure 7. This comparison shows the changes that will be made to NSIDC time series graphs.

Credit: NSIDC
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NSIDC is transitioning the sea ice extent time series graphs to show interquartile and interdecile ranges, with the median extent value, in place of standard deviations and the average values. Standard deviations are most useful with data that are clustered towards the average, or “normally distributed” like a bell curve, with few outliers. Sea ice extent data, however, has become skewed due to the strong downward trend in ice extent, with a wider spread of values and more values falling at the low end of the range. Interquartile and interdecile ranges, along with the median value, are better for presenting data with these characteristics. The interquartile and interdecile ranges more clearly show how the data are distributed and can better distinguish outliers, and so provide a better view of the variability of the data.

Further reading

Serreze, M. C., A. Crawford, J. C. Stroeve, A. P. Barrett, and R. A. Woodgate. 2016. Variability, trends and predictability of seasonal sea ice retreat and advance in the Chukchi Sea. Journal of Geophysical Research, 121, doi:10.1002/2016JC011977.

Sea ice hits record lows

Average Arctic sea ice extent for November set a record low, reflecting unusually high air temperatures, winds from the south, and a warm ocean. Since October, Arctic ice extent has been more than two standard deviations lower than the long-term average. Antarctic sea ice extent quickly declined in November, also setting a record low for the month and tracking more than two standard deviations below average during the entire month. For the globe as a whole, sea ice cover was exceptionally low.

Overview of conditions

sea ice extent map

Figure 1. Arctic sea ice extent for November 2016 was 9.08 million square kilometers (3.51 million square miles). The magenta line shows the 1981 to 2010 median extent for the month. The black cross indicates the geographic North Pole. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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In November 2016, Arctic sea ice extent averaged 9.08 million square kilometers (3.51 million square miles), the lowest November in the satellite record. This is 800,000 square kilometers (309,000 square miles) below November 2006, the previous lowest November, and 1.95 million square kilometers (753,000 square miles) below the 1981 to 2010 long-term average for November. For the month, ice extent was 3.2 standard deviations below the long-term average, a larger departure than observed in September 2012 when the Arctic summer minimum extent hit a record low.

At this time of year, air temperatures near the surface of the Arctic Ocean are generally well below freezing, but this year has seen exceptional warmth. The overall rate of ice growth this November was 88,000 square kilometers (34,000 square miles) per day, a bit faster than the long-term average of 69,600 square kilometers (26,900 square miles) per day. However, for a brief period in the middle the month, total extent actually decreased by 50,000 square kilometers, or 19,300 square miles—an almost unprecedented occurrence for November over the period of satellite observations. A less pronounced and brief retreat of 14,000 square kilometers (5,400 square miles) occurred in 2013.

Ice growth during November as a whole occurred primarily within the Beaufort, Chukchi and East Siberian Seas, as well as within Baffin Bay. Ice extent slightly retreated in the Barents Sea for the month. Compared to the previous record low for the month set in 2006, sea ice was less extensive in the Kara, Barents, East Greenland, and Chukchi Seas, and more extensive in Baffin Bay this year.

Conditions in context

sea ice extent plot

Figure 2a. The graph above shows daily Arctic sea ice extent as of December 5, 2016, along with daily ice extent data for four previous years. 2016 is shown in blue, 2015 in green, 2014 in orange, 2013 in brown, and 2012 in purple. The 1981 to 2010 average is in dark gray. The gray area around the average line shows the two standard deviation range of the data. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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air temperature plot

Figure 2b. This plot shows air temperature difference from average in the Arctic for November 2016. Air temperatures at the 925 hPa (approximately 2,500 feet) level in the atmosphere were above the 1981 to 2010 average over the entire Arctic Ocean and, locally up to 10 degrees Celsius (18 degrees Fahrenheit) above average near the North Pole. This is in sharp contrast to northern Eurasia, where temperatures were up to 4 to 8 degrees Celsius (7 to 14 degrees Fahrenheit) below average.

Credit: NSIDC courtesy NOAA/ESRL Physical Sciences Division
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Continuing the warm Arctic pattern seen in October, November air temperatures were far above average over the Arctic Ocean and Canada. Air temperatures at the 925 hPa level (about 2,500 feet above sea level) were above the 1981 to 2010 average over the entire Arctic Ocean and, locally up to 10 degrees Celsius (18 degrees Fahrenheit) above average near the North Pole. This is in sharp contrast to northern Eurasia, where temperatures were as much as 4 to 8 degrees Celsius (7 to 14 degrees Fahrenheit) below average (Figure 2b). Record snow events were reported in Sweden and across Siberia early in the month.

In autumn and winter, the typical cyclone path is from Iceland, across the Norwegian Sea and into the Barents Sea. This November, an unusual jet stream pattern set up, and storms instead tended to enter the Arctic Ocean through Fram Strait (between Svalbard and Greenland). This set up a pattern of southerly wind in Fram Strait, the Eurasian Arctic and the Barents Sea and accounts for some of the unusual warmth over the Arctic Ocean. The wind pattern also helped push the ice northwards and helps to explain why sea ice in the Barents Sea retreated during November.

Sea surface temperatures in the Barents and Kara Seas remained unusually high, which also helped prevent ice formation. These high sea surface temperatures are a result of warm Atlantic water circulating onto the Arctic continental shelf seas.

November 2016 compared to previous years

extent trend graph

Figure 3. Monthly November ice extent for 1979 to 2016 shows a decline of 5.0 percent per decade.

Credit: National Snow and Ice Data Center
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Through 2016, the linear rate of decline for November is 55,400 square kilometers (21,400 square miles) per year, or 5.0 percent per decade.

Warm Arctic delays ice formation in Svalbard’s fjords

temperature plot

Figure 4a. This plot shows ocean temperature by depth (y axis, in decibars; a decibar is approximately one meter) along a transect (x axis, in kilometers) from the outer continental shelf to the inner parts of Isfjorden, the largest fjord in the Svalbard archipelago, for mid November 2016. (Areas in black show the undersea topography.) Atlantic Water is as warm as 5 degrees Celsius (41 degrees Fahrenheit) and the surface layer still about 2 degrees Celsius (36 degrees Fahrenheit). The surface layer would normally have cooled to the salinity adjusted freezing point at (-1.8 degrees Celsius, 29 degrees Fahrenheit) at this time of year, enabling sea ice formation.

Credit: University Centre in Svalbard
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ocean current map

Figure 4b. The West Spitsbergen Current consists of three branches (red arrows) that transport warm and salty Atlantic Water northward: the Return Atlantic Current (westernmost branch), the Yermak Branch and the Svalbard Branch. The Spitsbergen Trough Current (purple) transports Atlantic Water from the Svalbard Branch into the troughs indenting the shelf along Svalbard. Since 2006, changes in atmospheric circulation have resulted in more warm Atlantic Water reaching these fjords. The blue and red circles on the figure indicate locations where hydrographic data were collected.

Credit: University Centre in Svalbard (UNIS)
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photo of moon

Figure 4c. An inky-black polar night—but no cooling. The moon is the only source of light in the Arctic now, and here shines over open water in Isfjorden, the largest fjord in the Svalbard archipelago, in mid-November 2016.

Credit: Lars H. Smedsrud
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In the Svalbard archipelago, sea ice usually begins to form in the inner parts of the fjords in early November. This November, however, no sea ice was observed. Throughout autumn, the wind pattern transported warm and moist air to Svalbard, leading to exceptionally high air temperatures and precipitation, which fell as rain.

Atmospheric and oceanic conditions in the fjord system were assessed by students from the University Centre in Svalbard. They noted an unusually warm ocean surface layer about 4 degrees Celsius (7 degrees Fahrenheit) above the salinity-adjusted freezing point (Figure 4a). Coinciding with exceptionally high air temperatures over Svalbard during autumn, the water has hardly cooled at all, and it is possible that no sea ice will form this winter.

The above average ocean temperatures arose in part from changes in ocean currents that bring warm and salty Atlantic Water into the fjords. As the warm Gulf Stream moves east, it becomes the branching North Atlantic Drift. One small branch is named the West Spitsbergen Current (Figure 4b). This current flows along the continental shelf on the west coast of Svalbard and is one mechanism for transporting heat towards the fjords. Since 2006, changes in atmospheric circulation have resulted in more Atlantic water reaching these fjords, reducing sea ice production in some and stopping ice formation entirely in others.

Antarctic sea ice continues to track well below average

ice trend graph

Figure 5a. Monthly November Antarctic sea ice extent for 1979 to 2016 shows an increase of 0.36 percent per decade.

Credit: National Snow and Ice Data Center
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air temperature plot

Figure 5b. This plot shows air temperature difference from average in the Antarctic for October 27 to November 17, 2016. Air temperatures at the 925 hPa level (approximately 2,500 feet) during the period of rapid sea ice decline in Antarctica (October 27 through November 17) were 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) above average near the sea ice edge.

Credit: NSIDC courtesy NOAA/ESRL Physical Sciences Division
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ice concentration anomaly plot

Figure 5c. This map of sea ice concentration difference from average for November 2016 shows very low ice extent in three areas of the ice edge (near the Antarctic Peninsula, near the western Ross Sea and Wilkes Land, and near Enderby Land) as well as extensive areas of lower-than-average concentration within the interior ice pack in the Weddell Sea, Amundsen Sea, and near the Amery Ice Shelf. Sea Ice Index data.

Credit: National Snow and Ice Data Center
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This year, Antarctic sea ice reached its annual maximum extent on August 31, much earlier than average, and has since been declining at a fairly rapid pace, tracking more than two standard deviations below the 1981 to 2010 average. This led to a new record low for the month of November over the period of satellite observations (Figure 5a). Average extent in November was 14.54 million square kilometers (5.61 million square miles). This was 1.0 million square kilometers (386,000 square miles) below the previous record low of 15.54 million square kilometers (6.00 million square miles) set in 1986 and 1.81 million square kilometers (699,000 square miles) below the 1981 to 2010 average.

For the month, Antarctic ice extent was 5.7 standard deviations below the long-term average. This departure from average was more than twice as large as the previous record departure from average, set in November 1986.

Ice extent is lower than average on both sides of the continent, particularly within the Indian Ocean and the western Ross Sea, but also to a lesser extent in the Weddell Sea and west of the Antarctic Peninsula in the eastern Bellingshausen Sea. Moreover, several very large polynyas (areas of open water within the pack) have opened in the eastern Weddell and along the Amundsen Sea and Ross Sea coast.

Air temperatures at the 925 mbar level were 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit) above average near the sea ice edge during late October and early November, corresponding to the period of rapid sea ice decline (Figure 5b).

The entire austral autumn and winter (since March 2016) was characterized by generally strong west to east winds blowing around the continent. This was associated with a positive phase of the Southern Annular Mode, or SAM. This pattern tends to push the ice eastward, but the Coriolis force acting in the ice adds a component of northward drift. During austral spring (September, October and November), the SAM index switched from strongly positive (+4 in mid-September, a record) to negative (-2.8 in mid-November). When the westerly wind pattern broke down in November, winds in several areas of Antarctica started to blow from the north. Over a broad area near Wilkes Land, the ice edge was pushed toward the continent. Areas with southward winds were also located between Dronning Maud Land and Enderby Land, and near the Antarctic Peninsula. This created three regions where ice extent quickly became much less extensive than usual (Figure 5c), reflected in the rapid decline in extent for the Antarctic as a whole. Interspersed with the areas of compressed sea ice and winds from the north, areas of south winds produced large open water areas near the coast, creating the polynyas.

Arctic sea ice loss linked to rising anthropogenic CO2 emissions

co2 plot

Figure 6. This plot shows the relationship between September sea ice extent (1953 to 2015) and cumulative CO2 emissions since 1850. Grey diamonds represent the individual satellite data values; circles represent pre-satellite era values; the solid red line shows the 30-year running average. The dotted red line indicates the linear relationship of 3 square meters per metric ton of CO2.

Credit: D. Notz, Max Planck Institute for Meteorology High-resolution image

A new study published in the journal Science links Arctic sea ice loss to cumulative CO2 emissions in the atmosphere through a simple linear relationship (Figure 6). Researchers conducting the study, including NSIDC scientist Julienne Stroeve, examined this linear relationship based on observations from the satellite and pre-satellite era since 1953, and in climate models. The observed relationship is equivalent to a loss of 3 square meters (32 square feet) for every metric ton of CO2 added to the atmosphere, compared the average from all the climate models of 1.75 square meters (19 square feet). This smaller value, or lower sensitivity, from the models is consistent with findings that the models tend to be generally conservative relative to observations in regard to how fast the Arctic has been losing its summer ice cover. The observed rate of ice loss per metric ton of CO2 allows individuals to more easily grasp their contribution to Arctic sea ice loss.

Global sea ice far below average

sea ice extent plot

Figure 7. This time series of daily global sea ice extent (Arctic plus Antarctic, month and first day of month on the x axis) shows global extent tracking below the 1981 to 2010 average. Sea Ice Index data.

Credit:W. Meier, NASA Cryospheric Sciences, GSFC
High-resolution image

As a result of both Arctic and Antarctic sea ice currently tracking at record low levels, global ice extent near November’s end stood at 7.3 standard deviations below average (Figure 7). However, the processes governing the evolution of sea ice in both hemispheres is a result of different atmospheric and oceanic processes and geographies and it unlikely that record low conditions in the two hemispheres are connected. Also, it is not especially instructive to assess a global sea ice extent because the seasons are opposite in the two hemispheres. In November the Arctic is in its ice growth season while Antarctic is losing ice. Antarctic sea ice as a whole has slightly increased over the past four decades (but with the last two austral winters having average and below average extent, respectively). The slight overall increase in Antarctic ice over the satellite record can be broadly linked to wind patterns that have helped to expand the ice cover towards the north (towards the equator).

NASA Operation IceBridge completes its 2016 Antarctic campaign

sea ice photo

Figure 8. This photograph from Operation IceBridge shows broken floes of sea ice floating in the Weddell Sea. A large area of open water can be seen on the horizon.

Credit: J. Beitler/National Snow and Ice Data Center
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In October, four NSIDC personnel accompanied the NASA Operation IceBridge campaign on its airborne surveys over Antarctica. The campaign completed a total of 24 flights over the continent in October and November, covering sea ice, land ice, ice shelves, and glaciers as Antarctica headed into its austral summer. Missions surveyed sea ice in the Weddell and Bellinghausen Seas with instruments that measure both sea ice extent and thickness. These measurements add to a time series of data that measures changes in sea ice and helps researchers assess the future trajectory of the ice pack and its impact on the climate. Visual observations from the flights confirmed that areas in the Bellingshausen Sea that are typically covered in sea ice were open water this year.

One of this year’s missions flew over a massive rift in the Antarctic Peninsula’s Larsen C Ice Shelf. Ice shelves are the floating parts of ice streams and glaciers, and they buttress the grounded ice behind them; when ice shelves collapse, the ice behind accelerates toward the ocean, where it then adds to sea level rise. Larsen C neighbors a smaller ice shelf that disintegrated in 2002 after developing a rift similar to the one now growing in Larsen C.

The IceBridge scientists measured the Larsen C fracture to be about 70 miles long, more than 300 feet wide and about a third of a mile deep. The crack completely cuts through the ice shelf but it does not go all the way across it. Once it does, it will produce an iceberg roughly the size of the state of Delaware.

The mission of Operation IceBridge is to collect data on changing polar land and sea ice and maintain continuity of measurements between NASA’s Ice, Cloud and Land Elevation Satellite (ICESat) missions. The original ICESat mission ended in 2009, and its successor, ICESat-2, is scheduled for launch in 2018. Operation IceBridge, which began in 2009, is currently funded until 2019. The planned overlap with ICESat-2 will help scientists validate the satellite’s measurements.

Further reading

Nilsen, F., Skogseth, R., Vaardal-Lunde, J., and Inall, M. 2016. A simple shelf circulation model: Intrusion of Atlantic Water on the West Spitsbergen Shelf. J. Physical Oceanography, 46, 1209-1230. doi:10.1175/JPO-D-15-0058.1

Notz, D. and J. Stroeve. 2016. Observed Arctic sea-ice loss directly follows anthropogenic CO2 emission. Science, 11 Nov 2016: Vol. 354, Issue 6313, pp. 747-750. doi:10.1126/science.aag2345.

Parkinson, C. 2014. Global sea ice coverage from satellite data: Annual cycle and 35-year trends. Journal of Climate, December 2014. doi:10.1175/JCLI-D-14-00605.1.

References

Fetterer, F., K. Knowles, W. Meier, and M. Savoie. 2016, updated daily. Sea Ice Index, Version 2. Boulder, Colorado USA. NSIDC: National Snow and Ice Data Center. doi:10.7265/N5736NV7.