September 17, 2010
Ozone Hole Depletion Has Stopped: UN
Scientists with the United Nations (UN) announced Thursday they found that the Earth's protective ozone layer in the upper atmosphere has stopped thinning out and should be mostly restored by the middle of this century thanks to a ban on dangerous chemicals that float up into the air.
The "Scientific Assessment of Ozone Depletion 2010" report said a 1987 international treaty that prohibited further use of chlorofluorocarbons (CFC) had been overly successful. CFC was widely used in refrigerators, aerosol sprays and packaging foams for many years.The ozone provides a natural protective filter against the harmful ultra-violet rays from the sun, which cause sunburn, cataracts and skin cancer. The rays can also be destructive to vegetation.
The hole in the ozone was first observed over the Antarctic in the 1970s and the alarm was raised in the 1980s after it was found to be worsening under the onslaught of CFCs. The shocking discovery prompted 196 countries around the world 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 depletion over the past decades," World Meteorological Organization head of research Len Barrie told the AFP news agency.
Barrie believes that global ozone, including polar region ozone is "no longer decreasing but not yet increasing" either.
Scientists working on ozone assessments now expect the ozone layer to be restored to 1980 levels sometime between 2045 and 2060, according to the report, somewhat earlier than originally expected.
Although CFCs have been banned, they accumulated and persist in the atmosphere and the effect of the chemical will still take years to filter out.
The South Pole ozone hole, which varies in size and is closely monitored when it appears each year in the spring, is likely to persist even longer and may even be affected further by climate change, the report said.
Scientists are still trying to figure out the complex interactions between ozone depletion and global warming, Barrie explained. "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," he added.
CFCs are classified as greenhouse gases and contribute to global warming. So the phase out of the harmful chemicals "provided substantial co-benefits by reducing climate change," the report stated.
Barrie estimated that the phase out also saved the atmosphere from nearly 10 billion tons of such emissions annually.
However, the ozone-friendly hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) that replaced CFCs in plastics and refrigerants are also considered powerful greenhouse gases.
HFCs are regarded as 14,000 times more potent than carbon dioxide (CO2). HFC emissions are growing by 8 percent per year, according to UN agencies.
"This represents a further potential area for action within the overall climate change challenge," said UN Environment Program chief Achim Steiner in a statement.
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