And now for the good news - Ozone Layer heals itself
by Jeni Bone on 21 Dec 2010
Ozone and atmosphere - protecting Earth SW
Earth’s upper ozone layer has stopped thinning and could be restored by mid-century, according to the Scientific Assessment of Ozone Depletion 2010 report from the UN, released last month.
The ozone layer absorbs 93-99% of the sun’s high frequency ultraviolet light, which would otherwise harm life on Earth.
The report attributed much of the repair to the 1987 international treaty that phased out chlorofluorocarbons (CFCs) used in refrigerators, aerosol sprays and some packing foams.
'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,' said World Meteorological Organisation head of research Len Barrie. 'Global ozone, including ozone in the polar region is no longer decreasing but not yet increasing,' he added.
The 300 scientists who compiled the four yearly ozone assessment now expect that the ozone layer in the stratosphere will be restored to 1980 levels in 2045 to 2060, according to the report, 'slightly earlier' than expected. CFCs are classified among greenhouse gases that cause global warming, so the phase out 'provided substantial co-benefits by reducing climate change,' the report found.
It estimated that phasing out CFCs reduced emissions by 10 gigatonnes per annum, however, the ozone-friendly substances that have replaced CFCs in plastics or as refrigerants – hydrochlorofluorocarbons (HCFCs) and hydrofluorocarbons (HFCs) – are also powerful greenhouse gases.
'This represents a further potential area for action within the overall climate change challenge,' said UN Environment Programme chief Achim Steiner.
More at www.unep.org
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