Wellington, Sep 5 (IANS): The opening in the earth's stratospheric ozone layer over Antarctica is closing slowly and should recover completely in the later half of this century, though its effect on global climate change is still uncertain.

The Montreal Protocol, which effectively banned chlorofluorocarbons (CFCs), had helped reduce the size of the hole in the ozone layer, Xinhua quoted University of Canterbury academic Adrian McDonald as saying Thursday.

The protocol, which came into existence in 1989, is an international treaty to phase out substances believed to be responsible for ozone depletion.

If the international agreement is adhered to, the ozone layer is 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 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 cooperation.