A
new study led by a Georgia Tech climate scientist has shown
that Antarctic sea
ice has expanded despite global warming, unlike Arctic sea ice;
but this is expected to change as greenhouse gases continue to warm
Antarctic waters.
Jiping
Liu, a research scientist and leader of the study from Georgia Tech,
is now able to provide an explanation for the Antarctic's growing sea
ice over the past 30 years, even though global warming has claimed
much of the Arctic's sea ice.
According
to climate models and observations of sea-surface temperature and
precipitations from 1950 to 2009, ocean warming actually provoked
precipitation in the upper atmosphere, which falls as snow in the
Antarctic. The top layers of the ocean then becomes less dense
because the snow makes these surface layers less salty, thus making
them more stable. This prevents density-driven, warmer currents in
the deeper part of the ocean from reaching surface waters and from
ultimately melting
the Antarctic sea ice.
It
may seem like a contradiction that warm surface waters are what
causes precipitation that is helping create sea ice, yet also causes
the melting of sea ice when it rises, but the problem, according to
the study, is that oceans are becoming too warm in the Antarctic due
to human-caused global
warming.
Increased
amounts of greenhouse gases causes climate warming, and this warming
causes the precipitation in the Antarctic to become rain instead of
snow, which melts ice and snow at a much faster pace. The suns rays
are then absorbed into the dark ocean as the ice melts, which warms
the ocean even more, and eventually leads to the melting of more sea
ice.
Issues
associated with melting sea ice is that some
animals in the Antarctic rely on it for hunting and
survival, and it also could change the way water in the ocean travels
around the world, which could interfere with circulation patterns
that "provide nutrients for up to three quarters of marine
life."
Walt
Meier of the National Snow and Ice
Data Center (NSIDC) in Colorado noted that the results of
this study are not surprising and the acceleration of melting
Antarctic sea ice was previously predicted. He also mentioned that
this study disproves the idea that a decline in Arctic ice and
expansion of Antarctic ice results in a net zero effect because
Arctic ice is "multiyear," meaning that it persists through
the seasons, while Antarctic ice melts and forms every year and isn't
dictated by air temperature as much as it is wind and ocean
circulation.
The
study was published in Proceedings
of the National Academy of Sciences on
August 16 of this year.
