"The nay-sayers have all said Kyoto will never go into force, now they have been proven wrong," said climate campaigner Steve Sawyer of Greenpeace. "Now what they are saying is there will never be a second period."

Even before the United States, which produces a quarter of the man-made emissions blamed for causing global warming, pulled out, it was clear that Kyoto's aim to reduce greenhouse gas output by 5.2 percent of 1990 levels was just a first step.

Scientists say an emissions cut of at least 60 percent is needed to prevent catastrophic impacts of climate change this century, including rising sea levels, the spread of deserts and even worse weather-related disasters.

Under Kyoto, countries should start this year talking about a second commitment under which they accept bigger cuts.

Doubts that this would definitely happen emerged at the last global climate change meeting in December when Italy's environment minister broke ranks with the rest of the European Union and said a second round of binding targets was unlikely.

"After (2012) it is unthinkable to go ahead without the United States, China and India," Altero Matteoli said.

Developing countries were exempt from targets in the first commitment period.

"Seeing as these countries do not wish to talk about binding agreements, we must proceed with voluntary accords, bilateral pacts and commercial partnerships," Matteoli said.

RESULTS NEEDED

This week the European Commission poured more cold water on the EU's determination to keep Kyoto going post-2012 in the face of reluctance elsewhere in the world.

"The reduction commitments that the EU would be willing to take under such a regime should depend on the level and type of participation of other major emitters," it said.

Europe's influence on climate change policy will depend on its ability to live up to its own targets. The 15 EU countries that signed up en bloc have to reduce emissions by 8 percent of 1990 levels but in 2002 were only 2.9 percent below.

Some EU countries are really struggling. Spain's emissions are up 40 percent, way above its limit of a 15 percent increase.

"If Europe meets its target it will strengthen the hand of people pushing for binding emissions reductions," said Richard Tarasofsky of the London-based think-tank Chatham House.

"If that doesn't happen ... other countries will lose faith in the multilateral approach to climate change."

Even if the EU, Japan and Canada make it, their good example alone may not be enough to persuade the United States or developing countries to take on targets post-2012. But they may get involved in emissions cuts outside Kyoto, analysts say.

"There are a number of avenues which are quite distinct that are complementary to or separate from the Kyoto process," said Jonathan Pershing of US think-tank World Resources Institute.

US ACTS

California and northeastern states already have policies on cutting carbon dioxide, which could lead to pressure from companies to link US trading systems with other countries to improve liquidity, Pershing said.

Even the green groups, which continue to insist on binding targets that are Kyoto's core, say there is room for other approaches to combat climate change.

Greenpeace's Sawyer envisions Kyoto continuing after 2012, with newer, tougher targets and some new countries like Mexico and South Korea joining.

Alongside that would be global efforts to help developing countries "decarbonise" as their economies grow by promoting cleaner energy and reducing deforestation and a third track to help poor countries cope with climate-related disasters.