Arctic sea ice extent is now tracking below 2010, 2013, and 2014. Openings in the ice cover have continued to expand within the Beaufort and Chukchi seas. While the Northern Sea Route has opened, the Northwest Passage remains clogged with considerable ice in the channels of the Canadian Archipelago. However, some data sources indicate narrow openings in the ice where navigation may be possible.

Overview of conditions

Figure 1. Arctic sea ice extent for August 16, 2015 was 5.79 million square kilometers (2.24 million square miles). The orange line shows the 1981 to 2010 median extent for that day. 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

On August 16, 2015 sea ice extent stood at 5.79 million square kilometers (2.24 million square miles). This is 1.35 million square kilometers (521,200 square miles) below the 1981 to 2010 average, and 1.17 million square kilometers (451,700 square miles) above the level for the same date in 2012, the year of the record low extent.

The rate of ice retreat slowed compared to July, but remained faster than is typical for the month through the first half of August. Most of the ice in Baffin and Hudson bays has finally melted out. Large areas of open water and low concentration ice within the Beaufort and Chukchi seas continued to expand. Some of the low concentration ice depicted in the passive microwave data could be due to the presence of melt ponds on higher concentration ice. However, visible imagery from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on the NASA Terra and Aqua satellites confirm a very loose ice pack with considerable open water in the region. Most of the remaining ice appears to be fairly thick multiyear floes interspersed by thinner first-year ice that is rapidly melting out. In the eastern Arctic, the ice pack remains more consolidated.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of August 16, 2015, along with daily ice extent data for 2014, 2013, 2012, and 2010. 2015 is shown in blue, 2014 in green, 2013 in orange, 2012 in brown, and 2010 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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Atmospheric temperatures at the 925 millibar level during the first half of August were above average over the North Pole region and the Barents and Kara seas, but below average in the Laptev, East Siberian, Beaufort and Chukchi seas. This is a notable change from July, when above-average temperatures prevailed over most of the Arctic Ocean, including much of the Beaufort and Chukchi seas. Current conditions are likely due to a shift in atmospheric circulation from the July pattern of high sea level pressure centered roughly over the pole to a pattern of high pressure centered over the Kara and Laptev seas, and low pressure centered over the eastern Beaufort Sea. This low pressure brought colder air from the north into the western Beaufort Sea and the Chukchi Sea, and generally cloudier conditions to the region.

Forecasting the seasonal minimum

Figure 3. The above graph shows a forecast of mean probabilistic Arctic sea ice extent for September 2015 (issued August 9, 2015). The forecast value, or expected September mean Arctic sea ice extent, is 4.55+/-0.35 million square kilometers.


Credit: Andrew Slater, National Snow and Ice Data Center.
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Several methods have been developed to make predictions of the September minimum in Arctic sea ice extent. NSIDC research scientist Andrew Slater developed a method that uses a statistical approach to calculate the probability of ice being present at each location (i.e., at each grid cell). The method correlates ice concentration at the time the forecast is made (issue date) with concentration at a desired later time (forecast); the difference between those two times or dates is known as the lead-time. While not as sophisticated as approaches using coupled ocean-ice-atmosphere models, this statistical method has the advantage that the forecasts for all points are completely independent in both space and time; that is, the forecast at any given point is not affected by its neighbors, nor its result from the prior day. Forecast skill improves as lead-time decreases.

The model has performed well compared to forecasts submitted to the Sea Ice Outlook prediction network. For example, the years 2005, 2007, and 2012 were correctly predicted as being record breaking (at the time) 50 days in advance. September average extent at 50-days lead time has been predicted to within 100,000 square kilometers (2009, 2010, 2011), but has also been as far off as 600,000 square kilometers (2007, 2008). Forecasting at seasonal time scales is difficult, but the model does have genuine skill in September (using a metric of comparison of the forecast error variance with the historically observed [de-trended] variance as was used in Schröder et al, [2014]) at lead times as long as ninety days.

A passage to India by way of Russia

Figure 4. The image above shows Arctic sea ice extent on August 16, 2015 from the Multisensor Analyzed Sea Ice Extent (MASIE) data product.

Credit: National Snow and Ice Data Center
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The Northern Sea Route along the Russian coast appears to be open, both in the passive microwave imagery and in the Multisensor Analyzed Sea Ice Extent (MASIE) product that is more adept at detecting thin and deteriorating ice. MASIE still shows considerable ice north of the Taymyr Peninsula and the Severnaya Zemlya islands, but there is a narrow open water passage through the ice. On the other side of the Arctic, the Northwest Passage still contains a considerable amount of ice. According to MASIE, there is as yet no completely open route. Some passive microwave products, such as from the University of Bremen’s Advanced Microwave Scanning Radiometer 2 (AMSR2), indicate an open water route along Norwegian explorer Roald Amundsen’s historical route through the southern part of the Archipelago. The apparent discrepancy between MASIE and the Bremen product is likely due to thin, heavily melting ice not detected by passive microwave imagery.

A change in Antarctic sea ice

Figure 5a. The graph above shows Antarctic sea ice extent as of August 17, 2015, along with daily ice extent data for the record low year. 2015 is shown in blue and 2012 in green. 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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Figure 5b. The above images compare Antarctic sea ice concentration for August 1, 2015 and August 16, 2015. Data are from the Advanced Microwave Scanning Radiometer 2 (AMSR2) sensor on the Global Change Observation Mission 1st – Water (GCOM-W1) satellite.

Credit: Institute of Environmental Physics, University of Bremen
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Growth in Antarctic sea ice extent has leveled off, increasing by just 250,000 square kilometers (96,500 square miles) between August 1 and August 17. This slow rate of growth has brought this year’s sea ice extent to below the 1981 to 2010 average for the first time in nearly four years. Figure 5b shows ice retreat around the Antarctic Peninsula, in the Ross Sea, and around the coast of Wilkes Land. These areas of retreat are offset by some ice growth in the northern Amundsen Sea and off the coast of Enderby Land.

Arctic sea ice extent for June 2015 was the third lowest in the satellite record. June snow cover for the Northern Hemisphere was the second lowest on record. In contrast, Antarctic sea ice extent remained higher than average. The pace of sea ice loss was near average for the month of June, but persistently warm conditions and increased melting late in the month may have set the stage for rapid ice loss in the coming weeks. 

Overview of conditions

Figure 1. Arctic sea ice extent for June 2015 was 11.0 million square kilometers (4.24 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 June 2015 averaged 11.0 million square kilometers (4.24 million square miles), the third lowest June extent in the satellite record. This is 920,000 square kilometers (355,200 square miles) below the 1981 to 2010 long-term average of 11.89 million square kilometers (4.59 million square miles) and 150,000 square kilometers (58,000 square miles) above the record low for the month observed in 2010.

Ice extent remains below average in the Barents Sea as well as in the Chukchi Sea, continuing the pattern seen in May. While extent is below average in western Hudson Bay, it is above average in the eastern part of the bay and near average east of Greenland.

Ice loss typically quickens in June with the largest loss rate occurring in July, the warmest month of the year. A total of 1.61 million square kilometers (622,000 square miles) of ice was lost through the month, slightly slower than the 1981 to 2010 average rate of decline of 1.69 million square kilometers (653,000 square miles). By the end of the month, ice extent for the Arctic tracked within one standard deviation of the 1981 to 2010 average.

Conditions in context

Figure 2a. The graph above shows Arctic sea ice extent as of July 5, 2015, along with daily ice extent data for four previous years. 2015 is shown in blue, 2014 in green, 2013 in orange, 2012 in brown, and 2011 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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June 2015 was fairly warm in the Arctic. Air temperatures at the 925 millibar level (about 3,000 feet above the surface) were above average over much of the Arctic Ocean, notably in the Kara Sea (2 to 5 degrees Celsius or 4 to 9 degrees Fahrenheit above average) and in the East Siberian Sea (2 to 3 degrees Celsius or 4 to 5 degrees Fahrenheit above average).

Figure 2b. The plot shows Arctic air temperature anomalies at the 925 hPa level in degrees Celsius for June 2015. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division
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The especially warm conditions in the Kara Sea, where ice extent is below average, is consistent with a wind pattern tending to bring in warm air from the south. The wind flows along the northern flank of a low-pressure area centered over the Barents Sea. Northerly winds on the western side of this low-pressure area brought cool conditions to the Norwegian Sea. Temperatures in the northern and eastern Beaufort Sea and much of the Canadian Arctic Archipelago were near or slightly below average.

June 2015 compared to previous years

Figure 3. Monthly June ice extent for 1979 to 2015 shows a decline of 3.6% per decade relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center
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Arctic sea ice extent averaged for June 2015 was the third lowest in the satellite record. Through 2015, the linear rate of decline for June extent is 3.6 % per decade.

Northern Hemisphere snow cover

Figure 4a. This snow cover anomaly map shows how snow cover for June 2015 differs from the average snow cover for June from 1981 to 2010. Areas in orange and red indicate lower than average snow cover, while regions in blue had more snow than average.

Credit: National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab
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Figure 4b. The graphs shows snow cover extent anomalies in the Northern Hemisphere for June from 1967 to 2015. The anomaly is relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab
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June snow cover for the Northern Hemisphere averaged 5.45 million square kilometers (2.10 million square miles), the second lowest of the 48-year record. This ranking also holds for June snow cover assessed for North America at 4.09 million square kilometers (1.58 million square miles) and Eurasia at 1.36 million square kilometers (525,000 square miles).

June snow cover was especially low over Alaska and western Canada. This is in part related to last winter’s unusual jet stream pattern, discussed in our March post. The pattern brought unusually warm conditions to the region and promoted low sea ice extent to the Bering Sea and Sea of Okhotsk. Recall that the restart of the Iditarod Race had to be moved from Anchorage to Fairbanks because of poor snow conditions in the Alaska Range. This spring has also been warm and dry in Alaska. These conditions have contributed to a large number of lightning-induced wildfires in the state.

Sea ice loss and snowfall over Eurasia

Climate models predict that Arctic precipitation will increase through the 21^st century. As the climate warms, the atmosphere can hold more moisture, which means a greater poleward transport and convergence of moisture by the atmosphere. The decline in Arctic sea ice extent may also play a role, as more open water will provide a moisture source. One would expect this latter effect to be most pronounced in autumn, when there will be a strong temperature (hence moisture) contrast between the open water and overlying air, promoting strong evaporation into the atmosphere. A recent study by Wegmann et al. provides evidence that more open water in the Barents and Kara seas has indeed led to an increase in autumn snowfall over Eurasia. Their analysis is based on snow observations from over 800 Russian land stations and an analysis of atmospheric moisture transport.

Sea ice in Antarctica

Figure 5. Antarctic sea ice extent for June 2015 was 14.9 million square kilometers (5.76 million square miles). The magenta line shows the 1981 to 2010 median extent for that month. The black cross indicates the geographic South Pole. Sea Ice Index data. About the data

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

Sea ice extent in Antarctica averaged 14.93 million square kilometers (5.76 million square miles), the third highest June extent in the satellite record. Extent was slightly greater than the 1981 to 2010 average almost everywhere around the continent. The high amount of sea ice in the eastern Weddell and Ross seas is consistent with the pattern observed for the past several months.

Satellite data show unusually extensive sea ice growth along the western side of the Antarctic Peninsula. This new feature in sea ice growth could be influenced by the strong atmospheric wave-3 pattern that has persisted over the past few months. In a wave-3 pattern, there are three major low-pressure areas around the continent separated by three high-pressure areas. The low-pressure areas have been centered on the Antarctic Peninsula, the northwestern Ross Sea, and the eastern Weddell Sea.

Further reading

Wegmann, M., Y. Orsolini, M. Vasquez, L. Gimeno, R. Nieto, O. Bulygina, R. Jaiser, D. Handorf, A. Rinke, K. Dethloff, A. Sterin, and S. Bronnimann. 2015. Arctic moisture source for Eurasian snow cover variations in autumn. Environmental Research Letters, 10, doi: 10.1088/1748-9326/10/054015.

As winter turns to spring, the seasonal decline in Arctic sea ice kicks into gear. April was marked by rapid ice loss at the beginning and end of the month. Air temperatures were higher than average over much of the Arctic Ocean. In the Antarctic, sea ice extent was the highest seen in April in the satellite record. This month we introduce data sets and online tools from new sensors that—combined with older sources—provide a more complete picture of ice thickness changes across the Arctic.

Overview of conditions

Figure 1. Arctic sea ice extent for April 2015 was 14.0 million square kilometers (5.4 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 April 2015 averaged 14.0 million square kilometers (5.4 million square miles), the second lowest April ice extent in the satellite record. It is 810,000 square kilometers (313,000 square miles) below the 1981 to 2010 long-term average of 15.0 million square kilometers (6.0 million square miles) and 80,000 square kilometers (31,000 square miles) above the previous record low for the month observed in 2007.

Ice extent remained below average in the Barents Sea, the Sea of Okhotsk, and the Bering Sea. Sea ice was slightly more extensive than average off Newfoundland, in the Davis Strait, and in the Labrador Sea. The Labrador Sea is an important breeding area for harp and hooded seals in early spring. More extensive ice in this region favors more seal cubs being fully weaned before the ice breaks up, increasing their chance of survival.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of May 5, 2015, along with daily ice extent data for four previous years. 2015 is shown in blue, 2014 in green, 2013 in orange, 2012 in brown, and 2011 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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During April, the decline in ice extent starts to accelerate, though the total ice loss over the month is generally small. April 2015 was marked by a fairly rapid decline during the first week of the month, little change during the middle of the month, and then a steep decline over the final week. Overall, extent decreased 862,000 square kilometers (333,000 square miles).

April was marked by higher than average 925 hPa air temperatures (1 to 3 degrees Celsius or 2 to 5 degrees Fahrenheit) throughout the Arctic, except for Greenland and the Canadian Archipelago where temperatures were 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) below average. Temperatures were 6 to 8 degrees Celsius (11 to 14 degrees Fahrenheit) higher than average in the Kara Sea, linked to unusually low sea level pressure over the North Atlantic. Associated wind patterns also resulted in strong warming over the Eurasian Arctic.

April 2015 compared to previous years

Figure 3. Monthly April ice extent for 1979 to 2015 shows a decline of 2.4% per decade relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center
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Arctic sea ice extent averaged for April 2015 was the second lowest in the satellite record for the month. Through 2015, the linear rate of decline for April extent is 2.4% per decade.

New data on sea ice thickness

Figure 4. This map shows sea ice thickness in meters in the Arctic Ocean from March 29, 2015 to April 25, 2015.

Credit: Center for Polar Observation and Modelling, University College London
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Data from new sensors, combined with older sources, are providing a more complete picture of ice thickness changes across the Arctic. In a recently published paper, R. Lindsay and A. Schweiger provide a longer-term view of ice thickness, compiling a variety of subsurface, aircraft, and satellite observations. They found that ice thickness over the central Arctic Ocean has declined from an average of 3.59 meters (11.78 feet) to only 1.25 meters (4.10 feet), a reduction of 65% over the period 1975 to 2012.

In addition, near-real-time thickness data from the European Space Agency’s CryoSat-2 satellite are now available from the Centre for Polar Observation and Modelling at the University College London. The spatial pattern of ice thickness in spring is a key factor in the evolution of sea ice through the Arctic summer, and CryoSat-2 data bring the promise of regular sea ice thickness monitoring over most of the Arctic Ocean.

The data indicate that Arctic sea ice thickness in the spring of 2015 is about 25 centimeters (10 inches) thicker than in 2013. Ice more than 3.5 meters (11.5 feet) thick is found off the coast of Greenland and the Canadian Archipelago, and scattered regions of 3-meter (10 feet) thick ice extend across the Beaufort and Chukchi seas. Elsewhere, most of the ice is 1.5 to 2.0 meters (4.9 to 6.6 feet) thick, typical for first-year ice at the end of winter.

Older ice spreads out

Figure 5. These ice age maps show a change in distribution of older ice from just after the summer 2014 melt season (left) and the end of March 2015 (right).

Credit: NSIDC courtesy J. Maslanik and M. Tschudi, University of Colorado Boulder
High-resolution image

Thickness estimates from CryoSat-2 data and the Lindsay and Schweiger analysis agree well with reconstructions based on sea ice age produced at the University of Colorado Boulder. Since ice gets thicker as it survives several melt seasons, ice age is a good proxy for thickness. For example, the ice thickness map from CryoSat-2 (Figure 4) and the ice age map (Figure 5) both show increased ice thickness in the southern Beaufort Sea where there was a transport of 5+ year old ice this winter. Interestingly, the ice age map identifies the tongue of ice extending towards the New Siberian Islands as second-year ice, yet the ice thickness map shows that its thickness is more similar to first-year ice.

Arctic sea ice age data are now publicly available from NSIDC and can be viewed interactively on the NSIDC Satellite Observations of Arctic Change Web site. Data are currently available through December 2012.

After the 2014 September minimum, first-year ice expanded through the winter growth season and older ice was redistributed around the Arctic Ocean. Figure 5 shows that winds have compressed second-year ice towards the coast of Greenland and the Canadian Archipelago. Old multi-year ice (4+ years old) drifted into the Beaufort and Chukchi seas and spread out, with first-year ice forming between parcels of the older ice. Some of the multi-year ice (both second-year and older) drifted out of the Arctic through Fram Strait on its way to melting in the warm waters of the North Atlantic.

Overall, the area of second-year ice decreased by more than a third during the winter, while ice of four years and more declined by about 10%. In recent years, the Beaufort and Chukchi seas have seen substantial loss of ice during summer, even of the thicker, older ice.

Antarctica reaches record ice extent, but temperature trends vary

Figure 6. The graph above shows Antarctic sea ice extent as of May 5, 2015, along with daily ice extent data for four previous years. 2015 is shown in blue, 2014 in green, 2013 in orange, 2012 in brown, and 2011 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

Antarctic sea ice extent averaged 9.06 million square kilometers (3.5 million square miles) for the month and is now the highest April extent in the satellite record. April extent was 300,000 square kilometers (116,000 square miles) higher than the previous record observed in 2014, and 1.70 million square kilometers (656,000 square miles) above the 1981 to 2010 long-term average. The Antarctic April extent was also above the two standard deviations of the long-term average.

The high sea ice extent in the Antarctic was a result of above-average extent in the Weddell Sea, and slightly more expansive ice cover in the Ross Sea. Interestingly, 925 hPa air temperatures over a wide area in the Weddell Sea were 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) above average for the month of April. Lower-than-average air temperatures (1 to 4 degrees Celsius or 2 to 7 degrees Fahrenheit below average) were found in the Ross Sea, but only in the far west and not near the regions of record ice extent. While there remains considerable year-to-year variability of sea ice extent in the Antarctic, the trend in April sea ice extent for the Antarctic from 1979 to 2015 now stands at 4.1% per decade.

References

Lindsay, R. and A. Schweiger. 2015. Arctic sea ice thickness loss determined using subsurface, aircraft, and satellite observations. The Cryosphere, 9, 269-283, doi:10.5194/tc-9-269-2015, 2015.

Tschudi, M., C. Fowler, and J. Maslanik. 2014. EASE-Grid Sea Ice Age. Boulder, Colorado USA: NASA National Snow and Ice Data Center Distributed Active Archive Center, doi:10.5067/1UQJWCYPVX61.

Arctic sea ice extent continues to track well below average, but it is still unclear whether March will see an increase in ice, or establish a record low maximum. Regionally, Arctic ice extent is especially low in the Sea of Okhotsk and the Bering Sea. In the Antarctic, sea ice shrank to the fourth highest minimum in the satellite record.

Overview of conditions

Figure 1. Arctic sea ice extent for February 2015 was 14.41 million square kilometers (5.56 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 in February averaged 14.41 million square kilometers (5.56 million square miles). This is the third lowest February ice extent in the satellite record. It is 940,000 square kilometers (362,900 square miles) below the 1981 to 2010 long-term average of 15.35 million square kilometers (5.93 million square miles). It is also 50,000 square kilometers (19,300 square miles) above the record low for the month observed in 2005.

With the Arctic Ocean completely ice covered, the remaining areas of potential new ice growth are limited to the margins of the pack in the northern Pacific and northern Atlantic. Sea ice extent is below average across the entire sea ice margin, most prominently along the Pacific sectors. A small region of above-average ice extent is located near Newfoundland and the Canadian Maritime Provinces.

The Arctic maximum is expected to occur in the next two or three weeks. Previous years have seen a surge in Arctic ice extent during March (e.g., in 2012, 2014). However, if the current pattern of below-average extent continues, Arctic sea ice extent may set a new lowest winter maximum.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of March 2, 2015, along with daily ice extent data for four previous years. 2014 to 2015 is shown in blue, 2013 to 2014 in green, 2012 to 2013 in orange, 2011 to 2012 in brown, and 2010 to 2011 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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Arctic sea ice extent increased by 429,000 square kilometers (165,600 square miles) during the month of February. This gain was slightly less than the average for the month. While low extent for the Arctic as a whole was largely driven by conditions in the Sea of Okhotsk and the Bering Sea, extent was also slightly below average along the Barents Sea and parts of the East Greenland Sea.

February 2015 compared to previous years

Figure 3. Monthly February ice extent for 1979 to 2015 shows a decline of 2.9% per decade relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center
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The monthly average Arctic sea ice extent for February was the third lowest in the satellite record. Through 2015, the linear rate of decline for February extent is 2.9% per decade.

Hot Bering(s)

Figure 4. The plot shows Arctic air temperature anomalies at the 925 hPa level in degrees Celsius for February 2015. Yellows and reds indicate higher than average temperatures; blues and purples indicate lower than average temperatures.

Credit: NSIDC courtesy NOAA Earth System Research Laboratory Physical Sciences Division
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The low ice extent in the Bering Sea and Sea of Okhotsk is linked to unusually warm conditions in the area. February air temperatures at the 925 hPa level were as much as 4 to 6 degrees Celsius (7 to 11 degrees Fahrenheit) above average in the northern Bering Sea, easternmost Siberia, and Sea of Okhotsk.

While these localized hotspots are in part driven by the low sea ice extent and the resulting large heat fluxes from the open water to the atmosphere, they are seen to be part of a broad area of unusually warm conditions extending across most of northern Eurasia, across Alaska, and into the western part of the United States. In contrast, cold and snowy conditions have persisted across the eastern half of North America. Broadly speaking, these opposing patterns of warmth and cold, along with low ice extent in the Sea of Okhotsk and Bering Sea, can be linked to an unusual jet stream pattern, with the jet lying north of its usual location over Eurasia and the North Pacific (meaning that warm air extends further north than is usual), and then plunging southwards over eastern North America.

Snow cover

Figure 5a. This snow cover anomaly map shows the difference between snow cover for February 2015, compared with average snow cover for February from 1981 to 2010. Areas in orange and red indicate lower than usual snow cover, while regions in blue had more snow than normal.

Credit: National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab
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Figure 5b. This graphs shows snow cover extent anomalies in the Northern Hemisphere for February from 1967 to 2015. The anomaly is relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center, courtesy Rutgers University Global Snow Lab
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This unusual jet stream pattern is clearly manifested in the pattern of Northern hemisphere snow cover for February. Snow extent was well above average over the northeastern U.S. However, the western U.S. and Northern Rockies saw less snow cover than average, especially along the Pacific coast where it has been particularly warm and severely dry. While the Tibetan Plateau saw a somewhat more extensive snow cover than average in December and January, extent for Tibet and Eurasia as a whole was below average in February. Higher-than-average snow cover in the eastern U.S. expanded and became more pronounced this month as well. All of these are continuations of the basic pattern seen in December and January, although the pattern of extensive snow over the northeastern U.S. became more pronounced this month. The low snow cover extent in much of Eurasia is consistent with the warmer-than-average conditions there as described above.

Seasonal Antarctic minimum reached

Figure 6a. This figure shows the concentration anomaly for February 2015 monthly average extent relative to the 1981 to 2010 average. Sea Ice Index data. About the data

Credit: National Snow and Ice Data Center
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Figure 6b. Monthly Antarctic February ice extent for 1979 to 2015 shows a trend of 5.0% per decade relative to the 1981 to 2010 average.

Credit: National Snow and Ice Data Center
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Antarctic sea ice extent reached its annual minimum, dipping to 3.58 million square kilometers (1.38 million square miles) on February 20. This is the fourth highest summer minimum extent on record, trailing behind 2008 (3.75 million square kilometers or 1.44 million square miles, highest), 2013, and 2003. The 2014 Antarctic minimum ranked the fifth highest (3.54 million square kilometers or 1.36 million square miles). For the month as a whole, February 2015 has the sixth highest ice extent (3.8 million square kilometers or 1.46 million square miles). The sea ice extent trend for February for 1979 to 2015 shows an increase of 5.0%  per decade. However, Antarctica’s sea ice extent is highly variable. As recently as 2011, Antarctic sea ice extent was at near-record low levels for the summer minimum.

Nevertheless, the recent series of high-ice-extent minima is part of a remarkable recent uptick in extent year-round for Antarctica, dominated by extensive ice in both the Weddell Sea (south of Africa) and the Ross Sea (south of New Zealand). Sea ice in the eastern Weddell Sea presently extends several hundred kilometers further north and east of its typical extent, while ice extent in the Ross Sea is presently near average. The debate continues regarding the cause of the recent Antarctic trends, but the best explanation so far involves a combination of strengthening low pressure in the eastern Ross Sea (the Amundsen Sea Low) and the eastern Weddell Sea, and a persistently positive phase of the Southern Annular Mode. The freshening of surface seawater around Antarctica may also play a role.

Global sea ice trends

Claire Parkinson of NASA recently presented the global average (Arctic plus Antarctic) trend in sea ice extent for the period 1979 to 2013. Overall, global sea ice has declined, despite the positive trend in Antarctic extent. The annual average trend is -35,000 square kilometers (-13,500 square miles) per year, or about -1.5% per decade. The strong Arctic decline in September leads to the largest magnitude monthly trend for global sea ice in that month, at -68,000 square kilometers (-26,300 square miles) per year, or -2.6% per decade. See the NSIDC FAQ on global sea ice here.

Further reading

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

Arctic sea ice extent remained about a standard deviation below average for the month of December. Compared to recent years, 2014 as a whole was rather unremarkable. The bigger story was the record high extents observed in the Antarctic through more than half of the year. At year’s end, Antarctic sea ice extent was again at a record high, but poised for a rapid decline as the austral summer wears on.

Overview of conditions

Figure 1. Arctic sea ice extent for December 2014 was 12.52 million square kilometers (4.83 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

Sea ice extent in December averaged 12.52 million square kilometers (4.83 million square miles). This is 540,000 square kilometers (208,495 square miles) below the 1981 to 2010 long-term average of 13.06 million square kilometers (5.04 million square miles) and 500,000 square kilometers (193,051 square miles) above the record low for the month observed in 2010.

Both Hudson Bay and Baffin Bay are now essentially completely ice covered. On the Atlantic side, recent winters have been characterized by reduced winter ice extent in the Kara and Barents seas. This is not the case for the winter of 2014 to 2015.

The only two regions where extent is notably below average are in the Bering Sea and the Sea of Okhotsk. This contrasts with recent winters when ice extent has been greater than average in the Bering Sea.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of January 4, 2015, along with daily ice extent data for four previous years. 2014 to 2015 is shown in blue, 2013 to 2014 in green, 2012 to 2013 in orange, 2011 to 2012 in brown, and 2010 to 2011 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

Sea ice extent grew 2.00 million square kilometers (772,000 square miles) during the month of December. This was about average for the month. Throughout the month, daily extents were about one standard deviation below 1981 to 2010 averages. This occurred despite the fairly warm conditions over the Eurasian side of the Arctic Ocean. As averaged over the month, air temperatures at the 925 hPa level in the Laptev and East Siberian seas were up to 5 degrees Celsius (9 degrees Fahrenheit) above average, linked to a region of unusually high pressure in the region that led to southerly winds.

December 2014 compared to previous years

Figure 3. Monthly December ice extent for 1979 to 2014 shows a decline of 3.4% per decade relative to the 1981 to 2010 average. The dashed line indicates a period of missing data from December 2, 1987 through January 12, 1988.

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

Arctic sea ice extent for December was the ninth lowest in the satellite record. Through 2014, the linear rate of decline for December extent over the satellite record is 3.4% per decade.

2014 in review

Compared to recent years, sea ice conditions observed throughout 2014 were largely unremarkable. Throughout the year, extent for the Arctic as a whole remained below average, but generally within two standard deviations of the average. The maximum extent observed on March 21 of 14.91 million square kilometers (5.76 million square miles) was the fifth lowest in the satellite record, with the minimum extent observed on September 17 of 5.02 million square kilometers (1.94 million square miles) being the sixth lowest on record. One event of note was in the Laptev Sea, where during August, open water was observed to extend to about 85 degrees latitude, less than 560 kilometers (350 miles) from the North Pole.

Summer weather conditions, which are known to strongly influence September minimum ice extent, were also largely unremarkable in 2014. Compared to the long term (1981 to 2010) climatology, sea level pressure over the period June through August 2014 was higher than average over much of the central Arctic Ocean, the Atlantic sector of the Arctic, and Greenland. While air temperatures at the 925 hPa level (approximately 3,000 feet altitude) were slightly above average over part of the central Arctic Ocean, they were below average over the Kara Sea and just north of Alaska.

By sharp contrast, sea ice in Antarctica was at satellite-era record high daily levels for much of 2014. On September 22, 2014, Antarctic ice extent reached 20.11 million square kilometers (7.76 million square miles). This was the first year in the modern satellite record that Antarctic ice extent climbed above 20 million square kilometers (7.72 million square miles).

As the year drew to a close, sea ice extent again reached record high levels for the date by declining far more slowly than usual. Extent anomalies are particularly large in the Ross Sea and Amundsen Sea regions, and in the northern Weddell Sea—areas that have been anomalously high for most of the calendar year. However, sea ice concentration in both these regions is now quite low, that is, the sea ice pack is loose and open. This is characteristic of dispersal of the ice by storms, and indeed strong low pressure anomalies were present in the eastern Ross Sea and northern Weddell Sea in the second half of December. The extent of this loose sea ice pack far to the north makes it likely that a rapid decline will occur as warmer summer weather arrives.

Losing the memory of low extent

Figure 4. This graph shows future projections of September sea ice extent under various future greenhouse gas emission levels. Limiting the warming in 2100 to about 1 to 2 degrees Celsius (2 to 4 degrees Fahrenheit) under the RCP2.6 emission scenario would help to stabilize ice conditions at levels seen today. The RCP8.5 emission scenario (warming by about 4 degrees Celsius 0r 7 degrees Fahrenheit by the end of this century) would result in a seasonally ice-free Arctic by the end of this century.

Credit: Julienne Stroeve
High-resolution image

In September of 2014, the Royal Society of London held a workshop focused on the reduction in Arctic sea ice extent. One outcome of this meeting was a greater understanding of the overall trajectory of September ice extent. In a nutshell, it appears that very large departures from the overall downward trend in September extent are unlikely to persist into the following September. If a given September has very low ice extent, strong winter heat loss results in strong ice growth, so that the “memory” of the low ice September ice extent is lost. If a given September has a high ice extent, winter heat loss is more limited, meaning less ice growth. Consequently, while there can be large departures from year to year from the downward linear trend in ice extent (e.g., September 2012 compared to 2014), the natural tendency is for the large departure to dampen out, so that, overall, ice extent stays on the long-term downward trajectory that will eventually lead to seasonally ice free conditions as the Arctic continues to warm in response to rising atmospheric concentrations of Greenhouse gases.

Arctic sea ice continued to expand throughout the month of October, remaining at near-average levels on the Atlantic side and below average on the Pacific side. In the Southern Hemisphere, Antarctic sea ice has declined after reaching its record maximum in October and is now nearly within two standard deviations of the long-term average.

Overview of conditions

Figure 1. Arctic sea ice extent for October 2014 was 8.06 million square kilometers (3.11 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

Sea ice extent in October averaged 8.06 million square kilometers (3.11 million square miles). This is 850,000 square kilometers (328,000 square miles) below the 1981 to 2010 long-term average of 8.91 million square kilometers (3.44 million square miles) and 1.29 million square kilometers (498,000 square miles) above the record low for the month observed in 2007.

Arctic sea ice extent continued to increase throughout the month of October. Ice extent in the Pacific side remains below average. Areas in the Beaufort Sea along the Canadian and Alaskan coasts, and in the Chukchi Sea along the coast of Siberia were still ice free at the end of October. The image of monthly average sea ice extent (Figure 1) shows a large polynya within the East Siberian Sea, but this area is now covered by ice. On the Atlantic side, extent remains at near-average levels.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of November 3, 2014, along with daily ice extent data for four previous years. 2014 is shown in blue, 2013 in green, 2012 in orange, 2011 in brown, and 2010 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

Through the month of October, the Arctic gained 3.39 million square kilometers (1.31 million square miles) of ice. This is faster than the average rate of ice gain for the month of October, but slower than the rate of ice gain seen in October 2012, after the record minimum of September 2012, and other recent Octobers.

Temperatures at the 925 hPa level show that the Arctic was 1 to 4 degrees Celsius (2 to 7 degrees Fahrenheit) higher than average everywhere, except in the Kara and Barents seas where air temperatures were 1 to 3 degrees Celsius (2 to 5 degrees Fahrenheit) lower than average. Lower than average temperatures in this region were also a persistent feature of summer 2014 and helped maintain a more extensive ice cover in the region than in recent summers.

Warm conditions were partly a result of the ocean releasing the heat gained during summer back to the atmosphere. In addition, sea level pressures were higher than average over the central Arctic Ocean and the Barents Sea, reflecting the negative phase of the Arctic Oscillation .

October 2014 compared to previous years

Figure 3. Monthly October ice extent for 1979 to 2014 shows a decline of 6.9% per decade relative to the 1981 to 2010 average.

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

Due to the relatively rapid ice growth during October, Arctic sea ice extent for October 2014 was the 6th lowest in the satellite record. Through 2014, the linear rate of decline for October Arctic ice extent over the satellite record is 6.9% per decade.

Amplified autumn warming

Figure 4. This figure shows average air temperature anomalies for October 2014 at each latitude from 50 North (left side of axis) to 90 North (right side of axis). The Y axis shows air pressure in millibars, indicating height above the surface.

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

Projections of climate change through the rest of the century show amplified warming in the Arctic compared to the rest of the planet. While there are a number of reasons for this, sea ice loss plays a strong role. With less ice in spring and summer, the upper ocean (the top 20 meters, or 66 feet) gains more heat through absorption of solar radiation. For the ocean surface to refreeze in autumn and winter, the ocean must first lose this extra heat. This is manifested as strong surface warming over the areas of sea ice loss during autumn. While the warming is greatest near the surface, the warming can extend to a considerable height in the atmosphere.

This October shows the expected pattern of amplified warmth. Warming was greatest near the surface at high latitudes (5 degrees Celsius, or 9 degrees Fahrenheit above average) and extended upwards to the 700 hPa level, roughly 3,000 meters (9,842 feet) above the surface. This pattern is similar to that observed in October 2007 and 2009. However, in other recent years the location of the warmest surface conditions shifted further south, or did not extend as far up in the atmosphere. Such variations point to the influence of other factors, including patterns of atmospheric circulation, cloud cover, and atmospheric humidity.

Arctic sea ice and the Madden-Julian Oscillation

Variations in large-scale atmospheric circulation patterns, such as the Arctic Oscillation , are known to affect the sea ice cover. These variations alter wind patterns that affect ice motion and bring in warm or cold air that influence ice melt and growth. For example, during a positive Arctic Oscillation phase, changes in the wind field help to push ice away from the coast of Siberia, allowing new ice to form and increasing the transport of ice out of Fram Strait. In the winters of the late 1980s and early 1990s, the Arctic Oscillation was in a persistent positive phase, helping to transport a large amount of thick, multiyear ice out of the Arctic through Fram Strait and leaving behind thinner ice that more easily melted the following summers.

A new study looks at the impact of a different mode of large-scale atmospheric variability, the Madden-Julian Oscillation, which appears to impact the ice cover on a shorter 30- to 90-day time scale. The Madden-Julian Oscillation is primarily driven by convection in the tropics, but causes changes in atmospheric circulation that impact the high latitudes. The impact on sea ice was found to be stronger during the winter season than in summer. It affected both the Atlantic and Pacific sectors and was confined to the marginal ice zone. The impact on sea ice also varies regionally, often showing opposing effects, such as between the Barents and Greenland seas in winter.

Large Antarctic sea ice variability

Figure 5. This image compares Antarctic sea ice extent for September 2014 (blue line) with extent for September 1964 (red line) and August 1966 (black line). The dotted ellipse marked A shows the eastern Weddell Sea and the dotted ellipse marked B shows the eastern Ross Sea.

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

After reaching a new record maximum extent this September, Antarctic sea ice extent has quickly declined, and is now back to levels seen in 2013 at this time of year. While almost the entire perimeter of Antarctica’s sea ice retreated slightly, two regions showed a larger retreat after the maximum: the eastern Weddell Sea (dotted ellipse marked A in Figure 5) and the eastern Ross Sea (dotted ellipse marked B in Figure 5). Both were areas of unusually extensive sea ice cover, and they contributed significantly to the record-setting level of ice extent in September. Weather patterns thirty days after the maximum changed markedly, with persistent warm northerly winds in these areas. Along the continent’s Pacific coast (Ross Ice Shelf and northern West Antarctic Ice Sheet) air temperatures at the 925 hPa level were 4 to 6 degrees Celsius (7 to 11 degrees Fahrenheit) above average. In the eastern Weddell Sea south of Africa, temperatures were 1 to 2 degrees Celsius (2 to 4 degrees Fahrenheit) higher than average. Moreover, a series of intense storms in the first half of October dispersed an area of sea ice near the Amery Ice Shelf and the southern Indian Ocean.

We noted earlier that estimates from early satellites, such as Nimbus I and II, show some brief instances of very extensive and very reduced Antarctic sea ice. For example, in September 1964 ice extent was greater in most of the Southern Ocean than this year, the exception being the Ross Sea. Two years later, in 1966, the August extent shrank to a level smaller than any for that month in the modern satellite record. As seen in Figure 5, the largest variations between this early record and today occur around 180 degrees East in the South Pacific. This area is particularly sensitive to impacts of increased westerly winds and the Amundsen Sea Low, an atmospheric pressure pattern that tends to spread the sea ice cover northward in the Ross Sea. The change in winds and the Amundsen Sea Low over the past thirty-five years is well documented.

Reference

Henderson, G. R., B. S. Barrett, and D. M. Lafleur. Arctic sea ice and the Madden-Julian Oscillation (MJO). Climate Dynamics , October 2014, Vol. 43, Issue 7-8, pp 2185-2196.

On September 17, Arctic sea ice reached its likely minimum extent for 2014. This is now the sixth lowest extent in the satellite record and reinforces the long-term downward trend in Arctic ice extent. Sea ice extent will now begin its seasonal increase through autumn and winter. Meanwhile, sea ice in the Antarctic has surpassed the previous record maximum extent set in 2013 and is now more than 20 million square kilometers (7.72 million square miles) for the first time in the past thirty-five years. It is too soon to determine if Antarctic sea ice has reached its annual maximum.

Please note that this is a preliminary announcement. Changing winds in the Arctic could still push ice floes together, reducing Arctic ice extent below the current yearly minimum. NSIDC scientists will release a full analysis of the Arctic melt season, and discuss the Antarctic winter sea ice growth, in early October.

Overview of conditions

Figure 1. Arctic sea ice extent for September 17, 2014 was 5.02 million square kilometers (1.94 million square miles). The orange line shows the 1981 to 2010 average extent for that day. 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

On September 17, 2014, sea ice extent dropped to 5.02 million square kilometers (1.94 million square miles). This appears to have been the lowest extent of the year. In response to the setting sun and falling temperatures, ice extent will now climb through autumn and winter. However, a shift in wind patterns or a period of late season melt could still push the ice extent lower. The minimum extent was reached two days later than the 1981 to 2010 average minimum date of September 15.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of September 17, 2014, along with daily ice extent data for four previous years. 2014 is shown in blue, 2013 in green, 2012 in orange, 2011 in brown, and 2010 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

This year’s minimum was 1.61 million square kilometers (622,000 square miles) above the record minimum extent in the satellite era, which occurred on September 16, 2012, and 1.20 million square kilometers (463,000 square miles) below the 1981 to 2010 average minimum.

Varying distribution of ice in 2014 versus 2013

Figure 3. This image compares differences in ice-covered areas between September 17, 2014, the date of this year’s minimum, and last year’s minimum, September 13, 2013. Light gray shading indicates the region where ice occurred in both 2014 and 2013, while white and dark gray areas show ice cover unique to 2014 and to 2013, respectively. Sea Ice Index data. About the data

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

This year, the ice cover remained more extensive over the Barents and Kara seas compared to last year. The most notable feature was the lack of ice north of the Laptev Sea that at one point in the melt season extended beyond 85 degrees North latitude, within 550 kilometers (342 miles) of the North Pole. This year was also unusual compared to recent years in that the Northwest Passage remained closed. On the other side of the Arctic, the Northern Sea Route or Northeast Passage opened with little ice near most of the shipping route along the coast of Siberia.

Antarctic overview and conditions

Figure 4. Antarctic sea ice extent for September 20, 2014 was 20.07 million square kilometers (7.75 million square miles). The orange line shows the 1981 to 2010 average extent for that day. The black cross indicates the geographic South Pole. Sea Ice Index data. About the data

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

While it is too soon to tell if sea ice around Antarctica has reached its annual maximum for the winter, it remained at record high daily levels for most of the year. On September 19, the five-day average ice extent surpassed 20 million square kilometers (7.72 million square miles) for the first time in the satellite record. Ice extent is above average in almost all sections of the Antarctic, particularly in the northern Ross Sea and Indian Ocean sectors. Near-average ice extent occurs south of South America in the northern Bellingshausen Sea and in a small region south of Australia.

Figure 5. The graph above shows Antarctic sea ice extent as of September 20, 2014, along with daily ice extent data for four previous years. 2014 is shown in blue, 2013 in green, 2012 in orange, 2011 in brown, and 2010 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

Previous minimum Arctic sea ice extents

The end of this year’s Arctic sea ice melt season is imminent and the minimum extent will be slightly lower than last year’s, making it the sixth lowest extent in the satellite record. Earlier in the month, a small area of the Laptev Sea ice edge was within five degrees of the North Pole. This appears to be the result of persistent southerly winds from central Siberia. Meanwhile, Antarctic sea ice is poised to set a record maximum this year, now at 19.7 million square kilometers (7.6 million square miles) and continuing to increase.

Overview of Conditions

Figure 1. Arctic sea ice extent for September 15, 2014 was 5.07 million square kilometers (1.96 million square miles). The orange line shows the 1981 to 2010 average extent for that day. 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 September 15 was 5.07 million square kilometers (1.96 million square miles). This is only 30,000 square kilometers (11,600 square miles) below the same date last year, yet sea ice extent remains low compared to the long-term 1981 to 2010 average. As is typical for this time of year, weather conditions near the ice edge heavily influence the timing of the minimum, which has occurred as late as September 23. We are now a day past the 1981 to 2010 average minimum date of September 15.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of September 15, 2014, along with daily ice extent data for four previous years. 2014 is shown in blue, 2013 in green, 2012 in orange, 2011 in brown, and 2010 in purple. The 1981 to 2010 average is in dark gray. Sea Ice Index data.

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

Sea ice extent declined at a rate of 28,700 square kilometers (11,100 square miles) per day through the first half of September. This is nearly twice as high as the 1981 to 2010 average rate of decline for this period of 16,200 square kilometers (6,200 square miles) per day. As was the case for the beginning of the month, extent remains below average in all sectors of the Arctic except for a region in the Barents Sea, east of Svalbard. There are areas of fairly low concentration ice north of the East Siberian and Chukchi seas that may still melt out or compact from wind-driven drifting.

However, as in 2013, a large area in the East Siberian Sea remains ice covered, helping to keep the overall extent higher for this time of year than observed since 2007. Last summer that area was covered by first-year ice that did not melt out under cooler-than-average conditions. This year, a region of second-year ice appears to have helped stabilize ice loss there.

The Northwest Passage remains closed, while the Northern Sea Route is still largely clear of ice.

A new ice edge

Figure 3a. The map at top shows the ages of ice in the Arctic at the beginning of March 2014; the bottom graph shows how the percentage of ice in each age group has changed from 1983 to 2014 .

Credit: NSIDC, courtesy M. Tschudi, University of Colorado
High-resolution image

Through the first half of September, the ice edge slowly retreated north of the Laptev Sea and is now within five degrees latitude of the North Pole. This is the most northerly position that the ice edge has been recorded over the period of satellite observations in this region. A large part of this region was also ice free in 2007. The reasons for the strong ice retreat in this sector are, at present, not entirely clear but we offer some initial insights.

Figure 3b. This map shows surface wind patterns over the Arctic region from June to August 2014.

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

In April, we discussed the pattern of ice age across the Arctic as the melt season began. In general, younger ice tends to be thinner ice. Areas of young ice are more likely to melt out during the summer than areas of old ice. The ice age figure from that post, reproduced here (Figure 3a), shows a strong northward extension of ice less than one year of age along the same general longitudes that open water has developed. Given the general circulation of the sea ice away from the Siberian shores, this area of thin ice prone to melting out would have tended to advance further northward through the melt season. Indeed, average sea level pressures this summer featured a pattern of surface winds particularly conducive to transporting thinner ice northward in the Laptev Sea sector (Figure 3b). To the east, winds were calmer and an arm of older, thicker second-year ice there may have helped to limit melt out and northward advection.

Sea surface temperature update

Figure 4. These maps show Arctic sea surface temperatures (left) and temperature anomalies (right) for August 2014, in degrees Celsius. Sea surface temperature data are from the National Climatic Data Center’s OIv2 “Reynolds” data set, a blend of satellite (Advanced Very High Resolution Radiometer) and in situ data designed to provide a bulk or mixed layer temperature. Ice edge data are from NSIDC near-real time passive microwave data.

Credit: Mike Steele/University of Washington
High-resolution image

As one may expect with an early retreat of sea ice, sea surface temperatures in the Laptev Sea were higher than average by up to 5 degrees Celsius (9 degrees Fahrenheit), with up to 3 degrees Celsius (5 degrees Fahrenheit) anomalies extending north of 80 degrees North for the first time since 2007. Early ice retreat and high sea surface temperatures are not unusual for this area and have appeared every summer since 2007, with the exception of 2008. The date of ice opening in the Laptev Sea is not particularly unusual in 2014 either. Open water and warming ocean temperatures started in early June. However, this summer there was a rapid northward progression of the ice edge in this area, especially along about longitude 140 degrees East, which allowed the sun to warm the resulting open water.

Over other parts of the Arctic, sea surface temperatures were not particularly noteworthy, except for cooler-than-average conditions in the northern Barents and Kara seas where the ice has remained extensive compared to recent summers. This reverses a recent trend toward warming and ice retreat in these areas, noted in last year’s sea surface temperature update. Preliminary analysis indicates that these changes are forced by local meteorological conditions, rather than oceanic heat transport by Atlantic water.

Further reading

Steele, M., S. Dickinson, and J. Zhang. 2014. Seasonal ice loss in the Beaufort Sea: Toward synchronicity and prediction. Journal of Geophysical Research-Oceans. In review.

Arctic sea ice extent is well below average, and large areas of low concentration ice are observed in the Beaufort Sea and along the Siberian coast. However, it is highly unlikely to set a record low at the end of this year’s melt season. Antarctic sea ice extent remains at record highs.

Overview of conditions

Figure 1. Arctic sea ice extent for August 17, 2014 was 6.11 million square kilometers (2.36 million square miles). The orange line shows the 1981 to 2010 median extent for that day. 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

Sea ice declined at slightly slower than average rates through the first part of August. By mid-August, extent was similar to this time last year, which makes it unlikely that this year’s minimum extent will approach the record low level observed in September 2012. On August 17, sea ice extent was 1.03 million square kilometers (398,000 square miles) below the 1981 to 2010 long-term average and 1.42 million square kilometers (548,000 square miles) above that observed in 2012 on the same date. Ice extent remains below average everywhere, except near Franz Joseph Land and in the northern part of the Barents Sea. Extent is particularly low in the Laptev Sea where open water now extends to about 85 degrees latitude, less than 560 kilometers (350 miles) from the North Pole. This is the one region of the Arctic where ice loss has been exceptional in 2014 compared to recent summers. Ice extent is also very low in the East Greenland Sea, possibly as a result of reduced ice transport through Fram Strait.

Conditions in context

Figure 2. The graph above shows Arctic sea ice extent as of August 17, 2014, along with daily ice extent data for the record year. 2014 is shown in blue and 2012 in green. The 1981 to 2010 average is in dark gray. Sea Ice Index data.

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

The first part of August was dominated by anomalously low sea level pressure over the Kara Sea, combined with anomalously high pressure over the central Arctic Ocean and Greenland, as well as the Beaufort and Chukchi seas. This led to warm air advection from the south over the East Siberian and Chukchi seas and extending into the central Arctic Ocean, with air temperatures at the 925 millibar height being nearly 8 degrees Celsius (14 degrees Fahrenheit) higher than average off the coast of Siberia near the New Siberian Islands. Sea ice concentrations in this region dropped compared to the beginning of August, and the waters along the coast of eastern Siberia are now mostly ice free. Ice concentrations are also low in the Beaufort Sea. Ice has continued to break up in the Kara Sea where it has been slow to melt out this summer. Nevertheless, air temperatures in the Kara Sea remain lower than average by 2 to 4 degrees Celsius (4 to 7 degrees Fahrenheit). As of mid-August, sea ice extent remains on track to end up somewhere between the sixth and the tenth lowest sea ice minimum.

Low ice concentration as seen from MODIS

Figure 3. This image shows true-color composites of the Arctic for July 9, 2014 and August 12, 2014 from the NASA Moderate Resolution Imaging Spectroradiometer (MODIS).

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

Visible satellite imagery from NASA’s Moderate Resolution Imaging Spectroradiometer (MODIS) reveal a diffuse ice cover in the Beaufort Sea, as well as in areas of the Laptev and East Siberian seas. Despite low ice concentrations, ice extent is right at the long-term average for the region, in stark contrast to 2012 when the ice edge had already retreated to north of 75 degrees latitude. Ice remains extensive in the Northwest Passage through the channels of the Canadian Arctic Archipelago. On the Eurasian side, the Northern Sea Route is mostly open except that some ice still blocks Vilkitsky Strait, the narrow strait between the Siberian coast and the islands of Severnya Zemlya separating the Kara and Laptev seas.

No new record low in 2014

Figure 4. The graph above shows projections of ice extent from August 1 through September 30 based on previous years’ observed retreat rates appended to the August 12, 2014 ice extent. Sea Ice Index data. About the data

Credit: Walt Meier, NASA GSCF
High-resolution image

During August, sea ice extent declines more slowly as the sun starts to set in the Arctic and the sea ice minimum approaches. Thus, the window is closing on potential ice loss through the remaining summer. A simple way to estimate how much ice loss may occur during the rest of the summer is to extrapolate daily ice loss, using rates of ice loss from previous years. The approach provides a reasonable bracket on possible scenarios through September. Using the 1980 rate of ice loss yields the highest potential minimum this year, because the end of summer rate of ice loss in 1980 was very slow. The lowest potential minimum is estimated using the 2012 rate of ice loss, as there was rapid ice loss in 2012. No scenario suggests a minimum near the record low year of 2012. Most likely this year’s minimum will be between 5.0 and 5.5 million square kilometers (1.9 and 2.1 million square miles).

Antarctic sea ice trend

Figure 5. These images show air temperatures in the Southern Hemisphere at 925 mb (about 2500 feet above sea level) for July 25 to August 9, 2014 (left) and May 9 to August 9, 2014 (right) compared to the long-term average.

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

Antarctic sea ice remains at a daily record high, and 1.19 million square kilometers (459,000 square miles) above the 1981 to 2010 average. Sea ice extent is now higher than average nearly everywhere around the continent, except for a portion of the northwestern Weddell Sea. This has occurred despite the fact that air temperatures at the 925 hPa level in the Ross and western Amundsen Sea have been much higher than average, by up to 8 degrees Celsius (14 degrees Fahrenheit), for the past two weeks. Longer term, the preceding three months (mid-May to mid-August) have been slightly warmer than average over most of the Antarctic sea ice areas. This supports the idea that the record or near record high Antarctic ice extents of 2014 have been driven by wind patterns and ocean conditions as discussed in our July post.