Geoscience Reference
In-Depth Information
ereignty claims can be settled, the passage
may become a summer reality in as little
as a decade. Canada more or less views the
Northwest Passage as its own Panama Ca-
nal, though no other nation agrees with
this contention.
Meanwhile, for the first time, thanks to
global warming, Canada has taken a strong
interest in the remote far north, building
small harbors and airstrips, and support-
ing mineral exploration, all in preparation
for the disappearance of the sea ice. A few
years back the Canadian government even
established a tiny Inuit settlement in the
far north to help territorial claims. The new
settlers barely survived the experiment be-
cause of the lack of fish and game available
for food at the ill-chosen site.
ally increased in area by 10% since 1980, a
fact sometimes cited as an indication that
the Earth is not warming but rather cool-
ing. But the Southern Ocean is not cooling.
Field measurements show that the ocean
water is actually warming at a rapid rate.
Hence it is likely that the increase in the area
of sea ice is related to changing ocean cur-
rents, which are related in turn to changing
wind patterns. Winds blowing offshore push
floating ice away from the land. Thus as the
Antarctic wind patterns change, the ice-free
water patches relocate and penguin colonies
migrate accordingly to get their food (krill)
from the sea.
Ozone depletion in the stratosphere has
very likely propagated downward and be-
gun playing a role in altering atmospheric
circulation and wind patterns. The winds
that the ozone hole generates also increase
salt spray in the atmosphere, which in turn
creates bright clouds, partially shielding
Antarctica from greenhouse gas warming.
As the ozone hole closes and its effect on
wind and ocean currents and cloud forma-
tion ceases, an increase in the rate of Ant-
arctic warming can be expected.
In 2010 the columnist George Will cre-
ated a storm of protest when he asserted
that the extent of global sea ice at the time
equaled that of 1979, implying that claims
of melting sea ice were false. Technically
he was right. However, he compared two
months of ice-cover data (combining both
Arctic and Antarctic sea ice) that were
thirty years apart, a process that ignored
a much bigger picture of gradual sea ice
Sea ice and the Southern ocean
At the other polar extreme, large areas of
sea ice are also found adjacent to Antarc-
tica. Because the Antarctic is a large conti-
nent surrounded by vast, open ocean (un-
like the enclosed Arctic Ocean), icebergs
by the thousands drift far to the north
every year. The sea ice extent during the
Southern Hemisphere winter (September)
is larger (17.9 million square kilometers, or
6.9 million square miles) than that of the
Arctic, but the summer (February) ice cover
is much smaller (2.8 million square kilome-
ters, or 1.1 million square miles).
Unlike its shrinking Arctic counterpart,
Antarctic winter floating sea ice has actu-
