A U.N. conference on climate change opened on Monday with delegates looking for any change in U.S. opposition to the Kyoto protocol after President George W. Bush''s re-election and Russian ratification of the agreement.
Russia''s ratification has created the most optimistic mood in years among environmentalists.
But even with Kyoto going into effect in February after a seven-year delay, the United States'' refusal to sign hangs over the 12-day Buenos Aires meeting, which has drawn 6,000 delegates from 194 countries.
President Bush withdrew in 2001 from the 128-nation Kyoto protocol, which seeks to cut carbon dioxide emissions by five percent from 1990 levels by 2012. He argued it was too expensive and wrongly excluded developing nations.
"It is a fantasy to try to mitigate climate change without the participation of the United States," said Juan Carlos Villalonga, director of campaigns at Greenpeace Argentina.
For many, one of the most interesting facets of this tenth convention of the parties, known as COP 10, will be any hint of change in the U.S. position.
Of the large industrialized countries, only the United States and Australia have refused to join the U.N. effort. But they account for around one-third of global emissions.
U.S. officials have shown no signs of budging in recent weeks and they question scientific estimates of a sharp rise in temperatures if emissions are not curbed.
Scientists warn of melting glaciers and polar ice caps, a rise in sea levels, extreme weather like heat waves, the spread of tropical diseases and the collapse of forests, coral reefs and farming.
To drive home the point, Greenpeace built a giant ark on Buenos Aires'' main avenue where some 2,000 people lined up Monday to take temporary refuge.
But even Kyoto''s backers say its provisions are not enough to reverse global warming and it is essential to get developing nations -- notably China, India and Brazil -- on board.
The Buenos Aires talks will touch on the participation of these countries in curbing emissions after Kyoto runs out in 2012. China, now an industrial powerhouse, is the second biggest producer of emissions behind the United States but is much lower on a per capita basis.
No major targets are expected from Buenos Aires. Rather, it is an opportunity for countries to begin discussing a timetable to define how much climate change the world can handle.
The European Union and some environmental groups want to limit any global temperature rise to 2.0 Celsius (3.6F). Temperatures have risen by 0.6 C since the late 1800s.
Environmental ministers from 80 countries will meet in the final days of COP 10, from December 15-17.
