Antarctic sea ice.
Photo: Mlenny/iStockphoto.com
Southern Hemisphere
There are far fewer observations of sea-ice thickness
Whole S Hemisphere +1.2
for the Antarctic than for the Arctic because of the
Bellingshausen Sea -5.3%
lack of submarine measurements. It is therefore
Weddell Sea +1.0
Indian Ocean +1.1
not possible to detect any trends in Antarctic sea-ice
West Pacific Ocean +1.2
thickness over recent decades.
Ross Sea +4.8
Change in annual mean sea ice
extent (% per decade)
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-
Figure 5.8: Regional changes in Antarctic annual mean sea-ice tion is a high research priority. Researchers are exam-
extent (% per decade) for the period 1979–2004.
ining changes in the atmospheric circulation of the two
Source: Data courtesy of NASA 2007a
9
polar regions as well as changes in ocean circulation.
CHAPTER 5 ICE IN THE SEA 71