Antarctic
Ozone Hole
Biggest Ever
by Jeremy Lovell, September
12, 2003
LONDON (Reuters) - The gaping, man-made hole in the ozone
layer over Antarctica has hit record proportions for this
time of year and could get bigger still within the next few
days, a leading scientist said Friday.
At
just short of 10.81 million square miles, the hole is a fraction
under the absolute record of 11 million, but it has historically
peaked in the second week in September and therefore could
theoretically grow further, British Antarctic Survey (BAS)
scientist Jonathan Shanklin told Reuters.
"It
was the largest it has ever been during August, and we are
waiting to see what happens over the next few days,"
Shanklin told Reuters by telephone from BAS headquarters in
Cambridge.
The
stratospheric ozone layer protects the earth's surface from
damaging ultraviolet rays that can cause skin cancer.
In
2002 the hole suddenly shrank, raising hopes it had turned
the corner and was starting to close. But Shanklin said scientists
now believed this was an abnormality due to atmospheric conditions,
and that the 2003 expansion was back to more normal activity.
Shanklin
said there was no direct link between the hole and the sharp
rise in skin cancers worldwide, which he said was closely
linked to changing lifestyles. However, he said the general
thinning of the ozone layer elsewhere because of chemical
depletion was almost certainly involved in the rise.
Shanklin,
one of the scientists who first discovered the ozone hole
in 1985, said he and his colleagues were still at a loss to
explain exactly why it had got so big in August.
"The
ozone hole is continuously in motion. It is rather like a
spinning top," he said.
The
1985 discovery forced a radical review and ultimately a complete
change in many industries that were belching ozone-depleting
chemicals into the atmosphere.
The
consequent drop in output of these chemicals began to bite
in 1994 and is now some 6 percent down on its peak.
However,
the time lag in the chemicals reaching the upper atmosphere
and attacking the key stratospheric ozone layer has meant
that the benefits of the output reduction has taken several
years to feed through.
"We
don't know if the hole has finally peaked, is over the top
and on the way down or still has a bit further to go,"
Shanklin said.
"We
are sure that we are pretty near the top, but we could have
to wait another decade to be able to say definitively that
the worst is over and it is starting to recover," he
added.
Shanklin
said it was vital for countries to stick to the Montreal Treaty
curbing the emission of ozone depleting chemicals.
But
he stressed that until there was similar accord on greenhouse
gases it was impossible to tell what effect there would be
on the atmosphere.
Most
major polluting nations have signed up to the Kyoto treaty
curbing carbon dioxide emissions. But the United States has
refused, even going so far as to refuse to accept that the
gas is a pollutant.
"It
would be excellent if all countries in the world pulled together
on greenhouse gases," Shanklin said. "The discovery
of the ozone hole proved we can change our atmosphere so easily.
It was a big surprise. There may well be further surprises
in store for us."
Source:
abcnews.go.com/wire/SciTech/reuters20030912_48.html