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3.3.2 Sea Ice

  • Page ID
    37154
  • In addition to land-based glaciers and ice sheets, the Arctic and Antarctic regions also contain sea ice, which is ice that forms over the open ocean and which often experiences large seasonal changes. Sea ice in Antarctica is relatively stable and experiencing minimal loss (Fig 3.3.2.1).

    AntarcticSeaIce.png

    Figure \(\PageIndex{1}\): Sea ice in the Antarctic region. The left-hand panel shows monthly extent in 2020 (blue line) and the minimum-recorded year of 2017 (red dotted line) compared to annual averages (dark gray band) and variation (light gray band) from 1981-2010. The right hand panel shows the monthly anomaly (solid black line) in June of each year compared to the average from 1981-2010 (dotted gray line). Figures from the National Snow and Ice Data Center1

     

    Sea ice in the Arctic Ocean is experiencing significant melting (Fig 3.3.2.2). Ice is very reflective and absorbs very little of the sun’s energy; however, liquid water absorbs more than it reflects. Consequently, melting of sea ice leads to a feedback loop in which more open water leads to warmer surface water, which melts more ice and leads to more open water and more melting of sea ice.

     

    ArcticSeaIce.png

    Figure \(\PageIndex{2}\): Sea ice in the Arctic Ocean. The left-hand panel shows monthly extent in 2020 (blue line) and the minimum-recorded year of 2012 (red dotted line) compared to annual averages (dark gray band) and variation (light gray band) from 1981-2010. The right hand panel shows the monthly anomaly (solid black line) in June of each year compared to the average from 1981-2010 (dotted gray line). Figures from the National Snow and Ice Data Center1

    The extent of sea ice loss in the Arctic Ocean is most clearly visible in the comparison between the record minimum year of 2012, and an average historical year, such as 1984 (Fig 3.3.2.3). Melting of sea ice in the Arctic Ocean is so severe that scientists predict the Arctic Ocean could be ice free in September by the year 2050.

     

    MinimumSeaIce.png

    Figure \(\PageIndex{3}\): Extent of Arctic sea ice in September (annual minimum) in 2012 (left) and 1984 (right). Minimum extent in 1984 matched the overall average for the time period 1979-2000. White circles in the center of the ice indicate data gaps from the incomplete paths of satellites. Images from NASA2.