Growing Antarctic Sea Ice Linked To Damaged Ozone
Date: 22-Apr-09
Country: NORWAY
Author: Alister Doyle, Environment Correspondent
Growing Antarctic Sea Ice Linked To Damaged Ozone Photo: Alister Doyle
A seal swims by icebergs off the British Antarctic Survey's
Rothera base January 23, 2009.
Photo: Alister Doyle
OSLO - An expansion of sea ice around Antarctica is linked to a hole in the
ozone layer high in the atmosphere, according to a study on Tuesday that
helps clear up a mystery about global warming.
The findings, by scientists at the British Antarctic Survey (BAS) and the
U.S. space agency NASA, explain an apparent contradiction between a thaw of
ice in the Arctic to record lows and an increase in ice around Antarctica
over the past 30 years.
"This new research helps us solve some of the puzzle of why sea ice is
shrinking in some areas and growing in others," John Turner of BAS, the lead
author of the report, said.
The scientists said damage by manmade chemicals to the ozone layer, which
shields the planet from ultra-violet rays that can cause skin cancer, cooled
the stratosphere and disrupted wind patterns around Antarctica.
The shift meant winds blew off the continent more often, cooling the sea and
creating more ice, they said. Scientists found a hole in the ozone layer
over Antarctica in the 1980s and traced it to chemicals once used in
refrigerants or hairsprays.
"While there is increasing evidence that the loss of sea ice in the Arctic
has occurred due to human activity, in the Antarctic human influence through
the ozone hole has had the reverse effect and resulted in more ice," Turner
said.
Sea ice around Antarctica has expanded at a rate of around 100,000 sq kms
(38,610 sq miles) a decade since the 1970s and covers an area of about 19
million sq kms at its winter maximum, doubling the size of the continent.
ARCTIC
By contrast, summer sea ice around the North Pole shrank in 2007 to the
smallest since satellite records began in the 1970s. The U.N. Climate Panel
says warming is caused by greenhouse gases from burning fossil fuels that
will bring more floods, heatwaves, droughts and rising sea levels.
"Although the ozone hole is in many ways holding back the effects of
greenhouse gas increases on the Antarctic, this will not last, as we expect
ozone levels to recover by the end of the 21st century," Turner said in a
statement.
Tom Lachlan-Cope, a BAS meteorologist and one of the co-authors of the study
in the journal Geophysical Research Letters, said Antarctica's sea ice had
expanded most in the Ross Sea, south of New Zealand.
"It's the classic way that sea ice is produced. You get an offshore wind
which blows the ice away from the shore and exposes open sea water which
then freezes over because of the cold air," he told Reuters.
Understanding Antarctica is a priority for scientists since it locks up
enough ice to raise sea levels by 57 meters (190 ft) if it were ever to
melt. Even a tiny thaw could threaten low-lying Pacific islands, or cities
from New York to Beijing.
(Editing by Farah Master)
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