WELLINGTON, Sept. 5 (Xinhua) -- The hole in the earth's stratospheric ozone layer over Antarctica is closing slowly and should be completely recovered in the later half of this century, but its effect on global climate change is still uncertain, a New Zealand expert said Thursday.
The Montreal Protocol, which effectively banned chlorofluorocarbons (CFCs), had helped reduce the size of the ozone hole, University of Canterbury academic Dr Adrian McDonald said in a statement.
The protocol, which entered into force in 1989, is an international treaty to phase out substances believed to be responsible for ozone depletion.
If the international agreement was adhered to, the ozone layer was expected to recover by 2050, McDonald said.
Ironically, stratospheric ozone depletion may have indirectly protected Antarctica from the worst of greenhouse gas-related warming.
"With the ozone recovery, the future of Antarctic climate is less certain, though the complex interactions in the atmosphere associated with climate change makes this region particularly hard to predict," he said.
"The increasing ozone hole has until now acted to change the circulation of the Southern Hemisphere so that the strong winds linked to the jet streams have moved towards the pole."
McDonald said ozone recovery should act to move the winds back towards the equator, but greenhouse gases might counteract this effect on the jet-stream positions, which help to control the width of tropical and polar weather belts.
Due to its widespread adoption and implementation, the Montreal Protocol has been hailed as an example of exceptional international co-operation.