Good news for a change - Oliver Milman: Ozone layer hole appears to be healing, scientists say
The vast hole in the
ozone layer above Antarctica appears
to be healing, scientists say, putting the world on track to eventually remedy
one of the biggest environmental concerns of the 1980s and 90s. Research by US and UK
scientists shows that the size of the ozone void has shrunk, on average, by
around 4m sq km since 2000. The measurements were taken from the month of
September in each year, when the ozone hole starts to open up each year.
The study, published
in Science, states that the phase-out of chlorofluorocarbon (CFC) chemicals
means that the ozone layer is “expected to recover in response, albeit very
slowly.” CFCs, once commonly found in aerosols and refrigeration, can linger in
the atmosphere for more than 50 years, meaning that the ozone hole will not be
considered healed until 2050 or 2060.
The Montreal protocol,
a 1987 international treaty ratified by all UN members, successfully spurred
nations to eradicate the use of CFCs in products. The agreement followed
fears that ozone depletion could cause serious health and environmental harm
through the ultraviolet light that would reach the surface of the Earth through
the ozone barrier. The UN estimates that2m cases of skin cancer a year have
been avoided through the phase-out of CFCs.
The ozone hole opened
up over the Antarctic due to the vast amounts of cloud that forms over the
coldest continent on Earth. This cloud helps the CFC chemicals linger, causing
the ozone layer to be eaten away. The void is at its greatest during the
southern hemisphere’s spring. Volcanic activity can
also spur greater ozone depletion, as scientists discovered last year when, to
their alarm, the largest ever ozone hole opened up in October, measuring more
than 20m sq km. This is thought to be
a blip, however, caused by volcanic activity in Chile. When scientists looked
at data from September, compared to the same month over the past decade, they
found a consistent shrinkage, with the opening up of the ozone hole occurring
later each year.
“When volcanoes team
up with man-made chlorine, it’s a toxic mix and Antarctica is particularly
vulnerable,” said study co-author Susan Solomon, of the Massachusetts Institute
of Technology. “But when we looked at
September we saw it was getting smaller. It was pretty cool to see it closing.
The chemicals will slowly decay over time.” The extreme cold of
Antarctica is thought to create a “feedback” effect that amplifies ozone
depletion, by creating clouds that cause more ozone to be eaten up. The extra
ultraviolet light is believed to have caused changes to plankton, but the
sparse wildlife in Antarctica, such as penguins, have not been severely
affected by the ozone hole.
“If you had to have an
ozone hole anywhere in the world, it would be Antarctica because it’s not
teeming with life,” said Solomon. “It was the canary in the coalmine that
showed us that if we didn’t back off with these chemicals, we’d have a crisis. “Britain, for example,
has around 5% less ozone than it did 30 years ago but it would’ve been twice as
bad as that if we didn’t phase out CFCs. There would be problems with skin
cancer, eye damage and damage to crops. We made a decision to avert a problem and
we ought to congratulate ourselves on that.”
Solomon said she was
hopeful the successful eradication of harmful CFCs would be followed by strong
international action to avert the worst consequences of climate change. “Obviously the
economics of global warming are different because the fossil fuel industry is
worth a lot more in dollars than the companies making these chemicals,” she
said. “But there are
important parallels. It was amazing to see how quickly innovation solved the
problem with CFCs so we got rid of them yet still have hair spray and air
conditioning. We’re starting to see the same thing with global warming. We
should look at the ozone problem and realize that nations can get together and
come up with solutions.”
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