- The disintegration of the huge Larsen B ice shelf in
Antarctica was an unprecedented event in the past 10,000 years of geological
history, a study has found.
-
- Research by scientists from Hamilton College in New York,
based on the scrutiny of six ice cores from the vicinity of the ice shelf,
found that a collapse of this size had not happened during the period since
the end of the last Ice Age.
-
- The piece of ice which sheered away from Larsen B into
the sea in 2002 was roughly the size of Luxembourg. The study, published
in the journal Nature, shows that the ice shelf had been thinning over
the millennia but went through a more rapid loss in recent decades, probably
due to global warming.
-
- In March 2002, scientists announced the Larsen B ice
shelf on the Antarctic Peninsula had entered a phase of rapid break-up
with more than 50 billion tons of ice spilling into the Weddell Sea to
form thousands of massive icebergs. It had been known for many years that
the ice shelf was thinning and in retreat but the speed of its final collapse
astonished scientists. It took just 35 days for the Larsen B ice shelf
to fall away completely after a Nasa satellite detected the first ruptures
in the 1,255 square miles of ice at the end of January 2002.
-
- Although the disintegration of ice shelves does not itself
cause sea levels to rise (because they are already floating), their loss
is thought to speed up the flow of ice from ice sheets on land, causing
sea levels to rise. Larsen B's smaller neighbour, Larsen A, broke off in
1995 and other much bigger ice shelves nearby, such as the Ross and Ronne,
are also considered to be at risk of disintegrating, according to studies
by the British Antarctic Survey in Cambridge.
-
- Researchers have measured a 2.5C increase in average
temperatures in the Antarctic peninsula over the past 50 years and many
scientists believe there is little doubt that this rise can be linked to
global warming and climate change exacerbated by man-made pollution.
-
- The latest study by a team led by Eugene Domack analysed
oxygen isotopes and the microscopic plankton called formanifera, which
are found in ice cores dating back 10,000 years. "We infer from our
oxygen isotope measurements in planktonic formanifera that the Larsen B
ice shelf has been thinning throughout the Holocene [from the present to
10,000 years ago], and we suggest that the recent prolonged period of warming
in the Antarctic peninsula region, in combination with the long-term thinning,
has led to collapse of the ice shelf," the researchers said.
-
- © 2005 Independent News & Media (UK) Ltd.
-
- http://news.independent.co.uk/world/science_technology/article303492.ece
|
