|
EARTH'S largest ice sheet has till now seemed well able to withstand
the effects of climate change, but it may have a hidden weakness. While
models predict the air over the East Antarctic ice sheet will remain
chilly enough to prevent significant melting for at least a century, a
new study suggests that rising sea levels - caused by melting elsewhere
- could be its undoing (Geology, vol 35, p 551).
A
team led by Andrew Mackintosh at Victoria University of Wellington, New
Zealand, gauged the ice sheet's past thickness by measuring how high
the ice had deposited boulders in Antarctica's Framnes mountains during
a period spanning the end of the last ice age. The team found that from
13,000 to 7000 years ago, when sea levels rose by 100 metres, the ice
sheet thinned by 200 to 350 metres.
Rising
waters would have lifted the buoyant ice sheet's edges off its rocky
base, causing pieces to detach and melt, the researchers say. Today,
meltwater from western Antarctica and Greenland is swelling oceans, so
eastern Antarctica could easily experience such calving again,
Mackintosh says. "The sheet is so large that even small changes in it
can have a significant impact," he says. The study does not predict how
much sea levels would have to rise before the sheet's edges start to
break away.
|
Health & Education 
