The hole in the ozone layer was the fifth-smallest since 1992, keeping it on track for recovery later this century, Nasa and the National Oceanic and Atmospheric Administration have reported.
The NOAA-Nasa report, released this week, credits this success to an international agreement signed in 1992 to phase out ozone-depleting chemicals that had been widening the hole over the Antarctic.
The hole in the ozone layer varies in size throughout the year. However, at the height of this year’s depletion season, from early September through mid-October, the average extent of the hole was about 18.71 million square kilometres, the NOAA-Nasa said. This was about 30 per cent smaller than the largest hole ever observed in 2006.
“Since peaking around the year 2000, levels of ozone-depleting substances in the Antarctic stratosphere have declined by about a third, relative to pre-ozone-hole levels,” said Stephen Montzka, a senior scientist with NOAA’s Global Monitoring Laboratory.
This year's ozone hole is already breaking up, nearly three weeks earlier than the established norm over the past decade.
Scientists have predicted the ozone layer over the Antarctic could heal as early as 2066.
“As predicted, we’re seeing ozone holes trending smaller in area than they were in the early 2000s,” said Paul Newman, a senior scientist with the University of Maryland, Baltimore County, and leader of the ozone research team at Nasa’s Goddard Space Flight Centre in Greenbelt, Maryland. “They’re forming later in the season and breaking up earlier. But we still have a long way to go before it recovers to 1980s levels.”
The ozone layer protects the Earth from solar radiation. However, man-made chlorofluorocarbons (CFCs) were discovered in the 1970s to deplete the ozone layer.
Under the Montreal Protocol, countries around the world came together in a rare show of international co-operation to phase out the use of CFCs, which were used in products such as refrigerants, propellants in aerosol cans and cleaning solvents, among others.
