Complex climate treaty challenges experts

By Gerard Wynn

VENICE, May 16 (Reuters) - Eighteen months before a new climate pact must be agreed, the world appears to be drifting in negotiations that could be the most complex ever, experts said.

The pact is needed to replace or extend the Kyoto Protocol on tackling global warming, whose first round ends in 2012.

Some 190 countries have agreed to clinch by November 2009 a new or amended pact, mindful it would take at least two years for so many national governments and parliaments to ratify it.

"At this point it's not clear about a path forward," said Robert Stavins, co-director of a Harvard University project to help design a new climate agreement, which hosted a meeting of academics, business, policymakers and environmental groups in Venice on Friday.

"You have to think creatively, take into account the science and politics. Not any world challenge requires this kind of collaboration. Sometimes it just takes political will for the obvious way forward."

The talks are complicated by an election in the United States, a top emitter of greenhouse gases, which will see a new president elected in November but not inaugurated until January, with senior officials in place as late as June 2009.

The present Kyoto binds 37 developed nations to cut emissions by 5 percent below 1990 levels by 2008-12, while the next treaty aims to include all countries, although at very different levels of commitment.

The problem is sharing the cost of re-deploying the world's entire energy system away from fossil fuels, and deciding how soon emerging economies adopt binding caps on greenhouse gases.