Argentina hosts the UN's annual climate change convention from December 6 to 17, just a month after Russian President Vladimir Putin put his signature to the international treaty on global warming.

Russia's official ratification of the treaty opened the way for it to become legally binding -- and for serious work on further steps needed to rein in human activities that are gradually changing Earth's delicately-balanced climate system.

The framework, negotiated in 1997, had previously been blocked because neither Russia nor the United States had ratified it.

The world's most ambitious and complex environmental accord legally commits industrialised countries to trimming output of six "greenhouse" gases, especially carbon dioxide (CO2), by at least 5.2 percent by 2012, compared with 1990 levels.

After it goes into effect February 16, rich countries who ratified it will be required to drastically cut emissions, which have soared in the meantime -- Canada by 20 percent and Japan by 12 percent, for example.

But for all its diplomatic and economic import, the treaty will have a minimal impact on the climate. The gases it regulates, products primarily of burning oil, gas and coal, can persist in the atmosphere for hundreds of years, and are already heating up the planet.

Scientists say that reductions of around 60 percent are urgently needed to avoid wreaking potentially catastrophic damage to the world's economies. The present so-called commitment period under Kyoto runs out in 2012.

Negotiations begin next year on the second commitment period after 2012, and countries will be under pressure to make far deeper cuts, include China and India in targeted reductions and coax the United States back into the multilateral fold.

The United States is now the world's top polluter, producing a quarter of CO2 emissions.

In March 2001, in one of his first acts after taking office, President George W. Bush said his country, even though it had signed the 1997 framework agreement, would not ratify the outcome.

He said the cost of meeting Kyoto's commitments would be too high for the US economy, and branded the treaty unfair, because only industrialised nations have to make targeted emissions cuts under the pact's timeframe.

Developing countries, including fast-growing India and China, are now responsible for about 40 percent of global emissions, but will overtake industrialized nations by about 2025, according to the International Energy Agency.

Emerging economies, led by India, consider any commitment to controlling emissions to be a hindrance to development.

European efforts to broach the future of negotiations stalled in a north-south clash in New Delhi in late 2002, and nearly killed a ministerial declaration.

Mindful of that experience, host country Argentina is proceeding cautiously, not even aiming for a joint declaration by some 70 environmental ministers who are to convene in the conference's final three days.

The thorniest issue is to be addressed only in a panel discussion themed, "The Convention after 10 years: accomplishments and future challenges."

Diplomats say the UN envisions organizing seminars in coming months to prepare for the start of official negotiations in November 2005 on the post-2012 period.

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