Ozone Hole Has Stabilised, Say Scientists

Hilary Osborne Guardian Unlimited - Wednesday August 23, 2006

Efforts to stop the hole in the ozone layer over the Antarctic from growing have worked, say leading scientists.

Two decades after research began, the US National Oceanic and Atmospheric Administration (NOAA) said the level of ozone-depleting gases was decreasing and it seemed the hole over the Antarctic had been stabilised.

David Hofmann, director of NOAA's global monitoring division, said: "We can say the patient isn't getting any sicker because the ozone hole isn't getting any deeper, any broader."

His colleague, senior scientist Susan Solomon, said the discovery of ozone depletion and the response of the scientific community were "nothing less than a scientific success story". But they said Antarctica had yet to see a build up in ozone levels and it was too early to talk of "an unambiguous recovery" in the ozone layer over the area.

Work began in 1986 following the discovery by a British team that there had been a decline in stratospheric ozone over Antarctica.

The ozone layer protects the planet from ultraviolet radiation, which at high levels poses a number of dangers, including increased risk of skin cancer and cataracts. The scientists discovered a hole in the layer that appears between September and November, the southern hemisphere's spring. Early theories about the cause included solar activity affecting the magnetic field, atmospheric motions and chlorofluorocarbons (CFCs), used in refrigerators and aerosols.

The work conducted by the scientists was the first to show a link between CFCs and ozone loss, and led to the Montreal protocol in 1987 under which countries agreed to stop producing CFC-like compounds by 1995. The gases had been used since the 1930’s in refrigerators and aerosol sprays and are found in insulating foam used in some buildings and white goods.

Although CFCs are not used in new goods, they are still being emitted as old fridges and foam are disposed off, and at much higher levels than anticipated, said Dr Solomon.

"This is working against the Montreal protocol to some degree," she said. Continued CFC emissions, together with climate change, could slow down the recovery of the ozone layer, but both scientists said they were "optimistic" it would one day return to previous levels.