Governments are looking at ways to keep the U.N.'s Kyoto Protocol going beyond 2012 in some form to defuse a standoff between rich and poor nations that threatens efforts to tackle global warming.
Negotiators from almost 200 nations will meet in Bangkok from March 3-8, after side-stepping the Kyoto issue at their last meeting in Mexico in December.
"There is some creative thinking going on" about Kyoto's future, said Jennifer Morgan, director of the climate and energy program of the Washington-based World Resources Institute.
The Kyoto Protocol obliges almost 40 industrialized nations to cut greenhouse gas emissions and is meant to underpin carbon trading, but existing curbs expire on December 31, 2012, and developed and developing nations are at odds over its future.
The U.N.'s climate chief, Christiana Figueres, said early this month the world needed an "intermediate solution" for Kyoto--whose text says it will be extended beyond 2012--since demands by rich and poor nations are diametrically opposed.
Japan, Russia, and Canada insist they will not extend cuts in greenhouse gases under Kyoto and want all top emitters, led by China and the United States, to agree to a new treaty beyond 2012.
Emerging nations, led by China and India, say rich nations must extend Kyoto to show leadership in combating climate change and averting what the U.N. panel of climate scientists says will be more floods, heat waves, droughts, and rising sea levels.
Kyoto obliges cuts in greenhouse gas emissions averaging at least 5.2 percent below 1990 levels during the period 2008-12. The United States is the only rich nation outside Kyoto and emerging nations have no binding goals.
Experts say all intermediate solutions have drawbacks.
One option is to preserve elements of Kyoto, such as a mechanism that promotes carbon-cutting investments in developing nations, while allowing each rich nation to set its own cuts in greenhouse gas emissions beyond 2012.
Another is to extend existing emissions cuts under Kyoto, perhaps until 2015, by when it may be clearer if a legally binding treaty is possible. But prospects for a binding deal have faded since a U.N. summit in 2009 fell short.
A radical idea is to revive an "Article 10," rejected by developing nations in 1997 when Kyoto was agreed, that would let developing nations list "voluntary commitments" to curb their rising greenhouse gas emissions as part of the text.
Or the European Union and other backers of Kyoto might push ahead and persuade Japan and others to commit to new, tougher emissions goals under an extended protocol. A continued small Kyoto group is likely to face calls to impose trade barriers on cheaper energy-intensive imports.
Or Kyoto might be abandoned and replaced by a new deal, as urged by Japan and others. That looks an unlikely outcome.