Small ozone hole over Antarctic not an indication of recovery

Oct 16, 2007, 13:02 GMT

Geneva - The ozone hole above the Antarctic is one of the smallest recorded in almost a decade, but this is not a sign that the hole is repairing faster than expected, the United Nations Weather Agency (WMO) said in its latest bulletin Tuesday.

WMO senior scientific officer, Geir Braathen said since 1998 only the ozone holes of 2002 and 2004 had been smaller than 2007. 'It should be pointed out that this is not a sign of ozone recovery,' he added.

Instead it was caused by the relatively mild temperatures in the Antarctic stratosphere. Ozone recovery meant a decline in ozone depleting substances.

'Low temperatures will increase ozone loss. When we have a mild winter we will have moderate ozone loss and that is what we see this year. So this is more a result of what we call inter-annual variability,' said Braathen.

Scientists expect relatively large holes to continue to appear in the Earth's protective atmosphere for the next 20 years even as the greenhouse gases, which destroy it, are reduced.

Last year the ozone hole above the Antarctic, which generally reaches its peak in October, was the biggest ever recorded, reaching 29.5 million square miles, with the ozone density the thinnest ever due to particularly cold temperatures.

This year the hole had started appearing quite early at the end of August leading to fears it would again be very large but the subsequent milder temperatures meant it did not develop.