Antarctic sea ice variability and trends, 1979-2010

Analyses of 32 yr (1979–2010) of Arctic sea ice extents and areas derived from satellite passive microwave radiometers are presented for the Northern Hemisphere as a whole and for nine Arctic regions. There is an overall negative yearly trend of −51.5 ± 4.1× 103 km2 yr−1 (−4.1 ± 0.3 % decade −1) in sea ice extent for the hemisphere. The yearly sea ice extent trends for the individual Arctic regions are all negative except for the Bering Sea: −3.9 ± 1.1× 103 km2 yr−1 (−8.7 ± 2.5 % decade −1) for the Seas of Okhotsk and Japan, +0.3 ± 0.8× 103 km2 yr−1 (+1.2± 2.7 % decade −1) for the Bering Sea, −4.4± 0.7× 103 km2 yr−1 (−5.1 ± 0.9 % decade −1) for Hudson Bay, −7.6± 1.6×103 km2 yr−1 (−8.5± 1.8 % decade −1) for Baffin Bay/Labrador Sea, −0.5 ± 0.3× 103 km2 yr−1 (−5.9 ± 3.5 % decade −1) for the Gulf of St. Lawrence, −6.5± 1.1× 103 km2 yr−1 (−8.6 ± 1.5 % decade −1) for the Greenland Sea,−13.5± 2.3× 103 km2 yr−1 (−9.2 ± 1.6 % decade −1) for the Kara and Barents Seas, −14.6± 2.3× 103 km2 yr−1 (−2.1± 0.3 % decade −1) for the Arctic Ocean, and−0.9± 0.4× 103 km2 yr−1 (−1.3 ± 0.5 % decade −1) for the Canadian Archipelago. Similarly, the yearly trends for sea ice areas are all negative except for the Bering Sea. On a seasonal basis for both sea ice extents and areas, the largest negative trend is observed for summer with the next largest negative trend being for autumn. Both the sea ice extent and area trends vary widely by month depending on region and season. For the Northern Hemisphere as a whole, all 12 months show negative sea ice extent trends with a minimum magnitude in May and a maximum magnitude in September, whereas the corresponding sea ice area trends are smaller in magnitude and reach minimum and maximum values in March and September.