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I'm Michael Starobin on the flight deck of NASA's
airborne science laboratory -- it's a customized DC-8.
We're in Punta Arenas, Chile on the trail ... of a mystery.
Kurtz: Ah, the current trend in Antarctic
sea ice is, it's been expanding. Starobin: We know this much already
global climate is getting warmer. Huge quantities
of ice are disappearing from both poles, and from glaciers around
the world. So if things are heating up? Why is
the quantity of ice increasing around the coast of Antarctica?
Kurtz: So it actually is very counter-intuitive that Antarctic sea ice
would be increasing when global temperatures are also increasing because you would
expect it to melt, such as has been happening in the Arctic.
Starobin: But it's not. Sea ice is increasing around the southernmost continent.
And scientists are trying to understand why. They're closing in
on suspect causes. Kurtz: The major component that
looks like it's contributing to the expansion of sea ice has been the increase of winds
from the Antarctic continent. Starobin: But why those winds are increasing
is still a matter of some debate, including an unexpected suspect.
Kurtz: One of the prevailing thoughts on why winds have
strengthened from the Antarctic continent outward to the sea, is because of
the ozone hole in the Antarctic. And
climate models have been run showing that if you have
an ozone hole, the winds are much stronger than if you don't
have an ozone hole. Starobin: But there are other causes too. A warmer planet
is likely to provoke higher rates of precipitation.
Kurtz: The increase in snowfall in particular would happen
and put fresh water into the ocean, at which point you have
a fresh layer that sits on top of a saltier layer.
Starobin: Freshwater freezes faster than saltwater. A warmer planet means more
fresh water, which is why a warmer planet means more
ice. Does the increase in sea ice around Antarctica
offset the decrease in sea ice in the North?
Kurtz: The decrease in Arctic sea ice has been about three times the increase in Antarctic sea ice.
So the actual amount of sea ice lost on the planet has been going down
substantially. It's a very unknown problem and
requires a lot of basically observations from scientists.
Starobin: Which is precisely why a team of specialized investigators
are in the field with Operation IceBridge, making vital observations
to better understand how Earth's climate is changing, and why.
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