The talks come as part of a UN-sponsored conference marking Sunday's 20th anniversary of signing of the Montreal Protocol, an international treaty seeking to end production of chemical compounds that contribute to ozone depletion.

Signatories of the Montreal Protocol, which cut emissions of chemicals harmful to Earth's ozone layer, hope to find a way to eliminate the hydrochlorofluorocarbons (HCFCs) that opened a hole in the Antarctic ozone layer.

The UN sponsor of the talks says repair of the ozone layer will also help with the warming of Earth's atmosphere, which has potentially disastrous effects on Earth's weather, sea levels, flora and fauna in coming years.

The 1987 Montreal Protocol is one of the most successful international responses to a global problem, according to former UN secretary general Kofi Annan.

Environmentalists hoped to repeat the success with the 1997 Kyoto protocol to cap emissions of so-called greenhouse gases, which gather in the atmosphere, and in the manner of a greenhouse allows the sun's rays in but does not allow the heat to escape.

However Kyoto, which expires in 2012, has not been adhered to by nations such as Canada, the United States, India and Austria. China is a signatory but is exempt due to its status as a developing nation.

Since the onset of the Industrial Revolution and the rise in emission of gases such as carbon dioxide and methane, the global warming effect has increased Earth's temperatures to an alarming degree, and is already blamed for melting polar ice caps.

Achim Steiner, executive director of the UN program for the environment, said in an interview published Saturday that the fight against global climate change and the fight to restore the ozone layer are linked.

"With the anniversary coming up (on Sunday), the enormous challenge has still not been met, and it offers the international community the chance to make rapid gains both concerning the ozone layer and global climate change," Steiner told the Montreal daily.

Haloalkane (HCFC) and CFC chemical compounds, once widely used as refrigerants and propellants in aerosol cans, have been largely curtailed by multilateral agreements in the Protocol.

CFC emissions opened a large hole in the ozone layer in the Earth's upper atmosphere, allowing more of the sun's harmful ultra-violet radiation to enter and raising the specter of increased cases of skin-cancer and eye cataracts.

If production of CFCs is halted and eliminated over the next 10 years the effect of global warming could be cut by 4.5 percent, Steiner said.

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