Sea Ice and Ocean Summary
Section Coordinator: Mary-Louise Timmermans
Yale University, New Haven, USA
November 15, 2012
|Arctic sea ice extent on Sept 16, 2012 (new record low). Black line is historical median extent in mid-Sept and yellow line is previous record low in 2007. Large version available from NOAA Climate.gov.|
Sea ice extent in September 2012 reached the lowest observed in the satellite record (1979-present). A related decline in the extent of the relatively thick multi-year ice, which forms in the central Arctic Basin, continued. The record low minimum extent occurred despite a relatively high maximum sea-ice extent in March 2012, which reflected extensive ice in the Bering Sea (Pacific Arctic). March to September 2012 showed the largest decline in sea ice between the maximum and minimum extents during the satellite record. August 2012 was a period of exceptionally rapid ice loss, with accelerated decline during an intense storm in early August in the East Siberian and Chukchi seas (Pacific Arctic). Ice retreated significantly around the perimeter of the ice pack, in contrast to the preceding two summers when a tongue of older ice in the East Siberian Sea persisted through the summer. While most Arctic boundary regions displayed anomalously warm sea-surface ocean temperatures in 2012 as a result of increased solar absorption into the upper ocean in large open-water regions, a strong cold anomaly was evident in August in the Chukchi Sea. This appears to have been related to the persistence of sea ice in this area even as the main body of the pack ice retreated northward. Relatively high freshwater and heat contents, with values comparable to 2011, persisted in the Beaufort Gyre in 2012. Pacific Water volume flux continued to increase, with flow through the Bering Strait in 2011 being about 50% higher than in 2001. The 2011 Bering Strait heat flux was comparable to the previous record high in 2007. The large-scale wind-driven sea ice and ocean circulation was anticyclonic (clockwise) in the Canadian sector of the Arctic between September 2011 and August 2012, while cyclonic circulation in the marginal seas drove intensified sea ice and surface water flow from the Kara and Laptev seas northward and then out of the Arctic Ocean via Fram Strait (Atlantic Arctic). Sustained sea-level rise, resulting from a combination of ocean surface warming and wind-driven dynamics, was observed through 2011.