Ozone layer on the mend, says report

By AAP with AG Staff 17 September 2010
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The ozone hole is sealing up faster than expected, but will not disappear until 2045 at the earliest.

THE PROTECTIVE OZONE LAYER in the Earth’s upper atmosphere has stopped thinning and should largely be restored by mid century thanks to a ban on harmful chemicals, UN scientists say.

Released on Thursday, The Scientific Assessment of Ozone Depletion 2010 says that a 1987 treaty which phased out chlorofluorocarbons (CFC) – substances used in refrigerators, aerosol sprays and some packing foams – had been successful in mitigating the damage to the atmosphere.

Ozone provides a natural protective filter against harmful ultra-violet (UV) rays from the Sun, which can cause sunburn, cataracts and skin cancer as well as damage vegetation.

Seasonal hole

First observations of a seasonal ozone hole appearing over the Antarctic occurred in the 1970s and the alarm was raised in the 1980s after it was found to be worsening under the onslaught of CFCs, prompting 196 countries to join the Montreal Protocol.

“The Montreal Protocol signed in 1987 to control ozone depleting substances is working; it has protected us from further ozone depleting over the past decades,” says Len Barrie head of research at the World Meteorological Organisation in Geneva, Switzerland. “Global ozone, including ozone in the polar region is not longer decreasing but not yet increasing,” he told journalists at a press conference.

The 300 scientists who compiled the four-yearly ozone assessment now expect the ozone layer in the stratosphere to be restored to 1980 levels sometime between 2045 and 2060,  “slightly earlier” than expected, according to the report.

Complex interactions

Although CFCs have long since been phased out, they continued to accumulate and persist in the atmosphere, and the effect of the curb on emissions have taken years to filter through. The ozone hole over the South Pole, which varies in size and is closely monitored when it appears in springtime each year, is likely to persist even longer and may even be aggravated by climate change, the report says.

Scientists are still getting to grips with the complex interaction between ozone depletion and global warming, Len says. “In the Antarctic, the impact of the ozone hole and the surface climate is becoming evident…This leads to important changes in surface temperature and wind patterns, amongst other environmental changes.”

16 September has been designated the ‘International Day for the Preservation of the Ozone Layer’, by the UN – a commemoration of the date in 1987 when nations first began to sign up to the Montreal Protocol.