Global Outlook for Ice & Snow

Antarctic sea ice. Photo: Mlenny/iStockphoto.com

There are far fewer observations of sea-ice thickness for the Antarctic than for the Arctic because of the lack of submarine measurements. It is therefore not possible to detect any trends in Antarctic sea-ice thickness over recent decades. The reasons for the very different trends in Arctic and Antarctic sea-ice extent over recent decades are not known at present and resolving this important ques- tion is a high research priority. Researchers are exam- ining changes in the atmospheric circulation of the two polar regions as well as changes in ocean circulation.

Southern Hemisphere

Whole S Hemisphere Bellingshausen Sea

+1.2

-5.3%

Weddell Sea Indian Ocean

+1.0 +1.1 +1.2

West Pacific Ocean

Ross Sea

+4.8 Change in annual mean sea ice extent (% per decade)

Figure 5.8: Regional changes in Antarctic annual mean sea-ice extent (% per decade) for the period 1979–2004. Source: Data courtesy of NASA 2007a 9

CHAPTER 5

ICE IN THE SEA

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