Long description

Two maps showing the average sea ice concentration from 1981 to 2010 in March and September in a polar stereographic plot of the Arctic with the North Pole at the centre. Open ocean is shaded dark blue and the continents are shaded grey. The sea ice concentration is shown as white for high concentration through to medium blue for low concentration at its edges. The sea ice extent is far larger for March (winter sea ice maximum), where the sea ice covers the whole Arctic Ocean and slightly beyond, than for September (late summer sea ice minimum), where it covers only the central part of the Arctic Ocean. The ice edge is not linked to any particular latitude. This is particularly striking for March, where the Hudson Bay in North America is ice covered (about 51° N) but there is open water up to the north of Svalbard (about 80° N).