Copernicus Climate Bulletin: Sea ice cover for September 2019



  • In August 2019, sea ice extent in the Arctic was about 36% lower than the 1981-2010 average, ranking the month as the third lowest September in our data record, while sea ice extent in the Antarctic was only slightly below average (-0.9%) and likely reached its annual maximum for 2019.

    Arctic

    1 month Arctic sea ice anomalies for September 2019

    photo:Copernicus Climate Change Service/ECMWF;desc:Time series of monthly mean Arctic sea ice extent (solid red) and sea ice area (dashed grey) anomalies for all September months from 1979 to 2019. The anomalies are expressed as a percentage of the September average for the period 1981-2010. Data source - ERA5

    The average Arctic sea ice extent in September 2019 was 4.2 million km2, that is 2.4 million km2 (or 36%) below the 1981-2010 average for September. The value for September 2019 is the third lowest in our dataset (which starts in 1979), with the lowest and second-lowest September sea ice extent dating back to 2012 and 2007, respectively. September is usually the month with the monthly minimum Arctic sea ice extent.

    September 2019 Arctic Sea Ice Concentration Map

    photo:Copernicus Climate Change Service/ECMWF;desc:Left - Average Arctic sea ice cover for September 2019. The thick orange line denotes the climatological sea ice edge for September for the period 1981-2010. Right - Arctic sea ice cover anomalies for September 2019 relative to the September average for the period 1981-2010. Data source - ERA5

    The map of sea ice concentration anomalies for the Arctic region for September 2019 shows much lower than average sea ice conditions across large sectors of the Arctic ocean, in particular in areas stretching from the Beaufort Sea via the Chukchi, East and West Siberian Seas towards Svalbard. There were very few areas with above average cover.

    Antarctic

    1 month Antarctic sea ice Sept 2019

    photo:Copernicus Climate Change Service/ECMWF;desc:Time series of monthly mean Antarctic sea ice extent (solid red) and sea ice area (dashed grey) anomalies for all September months from 1979 to 2019. The anomalies are expressed as a percentage of the September average for the period 1981-2010. Data source - ERA5

    Antarctic sea ice extent reached 18.2 million km2 on average in September 2019, which was 0.2 million km2 (or about 0.9%) below the 1981-2010 average for September. Even though many of the months leading up to September 2019 have shown large negative sea ice anomalies overall, the September 2019 sea ice extent is relatively close to average, ranking 15th lowest in our 41-year record. September is usually the month when Antarctic sea ice cover reaches its annual maximum extent. As such, if September is indeed the maximum also for 2019, it will be the 16th lowest monthly extent.

    1 month map Antarctic sea ice for September 2019

    photo:Copernicus Climate Change Service/ECMWF;desc:Left - Average Antarctic sea ice cover for September 2019. The thick orange line denotes the climatological ice edge for September for the period 1981-2010. Right - Antarctic sea ice cover anomalies for September 2019 relative to the September average for the period 1981-2010. Data source - ERA5

    The map of sea ice concentration anomalies for the Antarctic region in September 2019 reveals widespread areas of positive anomalies near the sea ice edge in broad sectors of the Southern Ocean, including most of the South Atlantic sector (40°W-10°W and 10°E-45°E) and of the Australian sector (80°E-180°E) . The region with the largest negative anomalies was in the South Pacific and included the northern portions of the Ross Sea and Amundsen Sea (180°W-90°W).

    Monthly sea ice area for 1979-2019

    1 month polar sea ice anomalies for September 2019

    photo:Copernicus Climate Change Service/ECMWF;desc:Area of the Arctic (upper) and Antarctic (lower) covered by sea ice, for the period January 1979 to September 2019, shown as monthly anomalies relative to 1981-2010. The darker coloured bars denote the September values. Data source - ERA5

    Variability and multidecadal trends in the areas of Arctic and Antarctic sea ice are evident in time series of monthly anomalies relative to average 1981-2010 values. The principal feature for the Arctic is a downward trend that is prominent after the year 2000. The largest negative trends have occurred in summer and autumn in recent years, but the last few years have also seen relatively low sea-ice area late in the winter, when sea-ice area reaches its annual maximum.

    Variability rather than trend predominates for the Antarctic. Episodes of markedly above-average sea-ice area occurred in 2007-2009 and 2013-2015. Conversely, Antarctic sea-ice area has been substantially below average for the past three years. Anomalies in November and December 2016 were more negative than for any month in the period from 1979.

    12 month range of polar sea ice area for September 2019

    photo:Copernicus Climate Change Service/ECMWF;desc:Annual range of sea-ice area from summer minimum to winter maximum for the Arctic (upper) and Antarctic (lower) based on monthly average values from 1979 to 2018. Maxima and minima for 2019 are based on the months of the year to date. Data source: ERA5

    An alternative view is provided by graphs of minimum and maximum monthly average sea-ice area for each year. Declining sea-ice area is evident for the Arctic in both minimum and maximum annual values. Variability is again seen to predominate for the Antarctic, where record or near-record low and high annual minima and maxima occur within a few years of each other.

    March is usually the month for which the average Arctic sea-ice area is a maximum, although in some years February is the month with the largest area. September is usually the month with the lowest average Arctic sea-ice area, but sometimes it is lower in August.

    February has been invariably the month with the lowest average Antarctic sea-ice area in this data record. September is usually the month with the largest average Antarctic sea-ice area. However, the maximum has occurred in October and August on two occasions.

    The lowest areas for the Arctic and Antarctic minima occurred in September 2012 and February 2018 respectively. The lowest areas for Arctic and Antarctic maxima occurred in February 2015 and September 1990 respectively.

    The sea-ice analysis page explains more about the nature, production and reliability of the data and information presented here.

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