Freshwater
Sea ice that has been above sea level for some time, like this
heap at
Shackleton's
Ocean Camp, tends to lose most of its salt and can be melted
for drinking water. This is essential, because despite holding
some 70 percent of all the world's freshwater, Antarctica gets
about as much precipitation as your average desert, and on sea
ice all that freshwater locked up in snow is not available
anyway. In summer, the melting of old sea ice can form
freshwater pools on the surface of newer ice, but in winter
you can't rely on these or even on significant snowfall. And
never eat snow; you'll expend more energy than you can afford
just melting it in your mouth.
The lack of freshwater increases the possibility that you'll
become dehydrated. Your chances are already high, because the
Antarctic's low humidity, high winds, and acute sunlight work
in conjunction with your body's lowered thirst drive and
hormonal changes to increase your susceptibility to the
condition. According to Survival in Antarctica, "a 2.5
percent loss of body fluid by weight results in a 25 percent
loss of abilities." Dehydration can make you feel tired and
less sharp mentally, and it can reduce your tolerance to cold,
thereby increasing your chances of contracting frostbite or
hypothermia.
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