Geoscience Reference
In-Depth Information
North Pacific and along the southern shore of the Kamchatka Peninsula, and
it covers Hudson Bay and Baffin Bay. In summer, these regions are generally
free of sea ice.
Antarctic sea ice extent displays an even larger seasonal variation than Arc-
tic sea ice (bottom two panels in
Fig. 2.34)
. This difference is, in large part,
an effect of continentality. Because the southern pole is covered by land and
the northern pole by water, Antarctic sea ice is located at lower latitudes than
Arctic sea ice on average. Approximately 19 # 10
6
km
2
of the ocean around
the Antarctic continent is covered with sea ice in the winter, but only about
3
# 10
6
km
2
survives the summer.
These large seasonal variations in polar sea ice make it clear that this compo-
nent of the climate system is capable of change. Record low values of Arctic sea
ice extent have been seen in recent years (
Fig. 2.35a)
, raising concern that Arctic
(a) Arctic Sea Ice Extent (area of ocean with at least 15% sea ice)
14
12
10
8
6
2011
2007
1979-2000 average
±2 standard deviations
4
2
August
September
October
November
December
(b) Antarctic Sea Ice Extent (area of ocean with at least 15% sea ice)
20
18
16
14
12
10
2011
2010
1979-2000 average
±2 standard deviations
8
6
August
September
October
November
December
Figure 2.35 Sea ice extent in the (a) Arctic and (b) Antarctic
for August through December. Image provided by National
Snow and Ice Data Center, University of Colorado, Boulder
(November 6, 2011).
