BONN, Germany Wider public unease about climate change and stronger economic growth are likely to be needed to revive sluggish U.N. talks after hopes for quick agreement on a treaty have fizzled, experts say.
Many nations at U.N. talks in Bonn from June 6-17 seem resigned to a long haul -- more like arms reduction talks or U.N. trade negotiations -- after failure to agree a binding U.N. climate deal by an end-2009 deadline at a summit in Copenhagen.
"Public awareness is really going to be the key," to spur a deal to avert heatwaves, droughts, floods and rising seas, said Rajendra Pachauri, head of the U.N. panel of climate scientists.
He told the Reuters Global Energy and Climate Summit that he believed many people, including in the United States, were "gradually getting more concerned about the realities of climate change," partly because of extreme weather.
In 2010, about 42 million people were displaced from their homes by natural disasters led by floods in China and Pakistan. Parts of the United States have been hit by the worst drought since the 1930s Dust Bowl.
Pachauri declined to predict when a deal could be reached. Some experts say it could be years away, or out of reach.
Robert Stavins, director of the Harvard Environmental Economics Programme, said it was wrong to expect a breakthrough treaty to solve climate change. He said a stronger economy was among important factors to allow slow, step-by-step action.
"With climate change we are in the position that the countries of the world were in at Bretton Woods after World War Two," he said of the conference that paved the way to reshaping the world economy.
"This is as difficult a problem," he said.
"I suspect we are looking at small steps rather than big strides at this stage," Britain's Energy Minister Charles Hendry told the Summit of the outlook for the next climate talks in Durban, South Africa in late 2011.
Among positive spurs to action, Hendry pointed to China, the top greenhouse gas emitter ahead of the United States.
"A few years ago we had seen China as a real block to progress. Now without any doubt it wants to be one of the world leaders on green technologies. That is changing the approach they take," he said.
Developing nations, however, insist on a deal in Durban to extend the Kyoto Protocol that obliges almost 40 developed nations to cut greenhouse gas emissions by 5.2 percent below 1990 levels over the period 2008-12.
"We have an international agreement, we are all obliged to fulfill it," said Pablo Solon, who leads Bolivia's delegation.
Kyoto nations Japan, Russia and Canada say they will not agree to new cuts beyond 2012 -- despite past promises. They say that a wider deal is now needed for all nations since Kyoto backers account for less than 30 percent of world emissions.
A complication is that the United States never signed up for Kyoto, arguing it would cost jobs and wrongly excluded binding targets for emerging countries.
Many developed nations want the Durban talks to build on a deal from Mexico in late 2010 to set up a green climate fund and limit any rise in temperatures to below 2 degrees Celsius (3.6 F) above pre-industrial times.
In Bonn, even the European Union, the main cheerleader among developed nations for a quick binding deal, has conceded that 2014-15 is now "broadly realistic" as a date for a broad deal.
Some experts say that action may have to wait for the next U.N. report on climate science, due in 2013-14 by Pachauri's Intergovernmental Panel on Climate Change (IPCC).
The last IPCC report in 2007 -- saying it was at least 90 percent certain that humankind was causing global warming -- helped spur environment ministers at talks in 2007 to set a two-year deadline for a deal. The Copenhagen summit fell short.
"The last IPCC report has probably exhausted its driving force," said Elliot Diringer, of the Pew Center on Global Climate Change, a Washington think-tank.
"Many people are looking for the next report. We need the global economy to continue to improve as well," he said. "And I do think there is a growing sense that something is amiss with the weather."
Meanwhile, the problem is getting worse. The International Energy Agency said last month that world emissions of carbon dioxide, the main greenhouse gas from human activities, rose 5.9 percent in 2010 to a record high.
(With extra reporting by Nina Chestney and Gerard Wynn in London)