A new round of UN climate talks opens in South Africa next week against a backdrop of record greenhouse-gas emissions but deep frustration in the quest for a solution.

Ahead of the 12-day meeting in Durban, the World Meteorological Organisation (WMO) on Monday reported that carbon dioxide (CO2), the biggest source of heat-trapping gases, had accelerated to a new peak in 2010.

"Even if we managed to halt our greenhouse-gas emissions today -- and this is far from the case -- they would continue to linger in the atmosphere for decades to come and so continue to affect the delicate balance of our living planet and our climate," said WMO's secretary general, Michel Jarraud.

Analysts say the UN process is still traumatised by the stormy 2009 Copenhagen Summit and, in Durban, faces a bustup over the Kyoto Protocol, the only pact setting legal curbs on greenhouse gases.

Brandished by defenders as a model of cooperation between rich and poor, Kyoto's first roster of pledges expires at the end of 2012.

But the treaty has been gravely weakened by the absence of the United States and lack of binding constraints over emerging giants such as China and India.

The stage is set for a "very complicated dance" over Kyoto's future, said Alden Meyer, a climate negotiations veteran from the Washington-based Union of Concerned Scientists.

"The worst-case scenario leads to gridlock and the collapse of the whole process," he said.

Canada, Japan and Russia have already refused to sign on for a second commitment period, objecting to the lack of legal binds on the world's biggest carbon polluters.

Europe says it can accept a continuation, provided China and the United States accept being part of a "global and comprehensive" agreement.

Some commentators think helping Kyoto to fade into obsolescence would improve chances of a global deal.

"Although the protocol remains an important emblem of multilateralism, it has become, in reality, more of an impediment than a means to genuine progress," Elliot Diringer of the Center for Climate and Energy Solutions, a US thinktank, wrote in the journal Nature last week.

Others fear dispatching Kyoto into limbo would be politically devastating.

Next June, world leaders gather for the 20th anniversary of the Rio Summit where the UN Framework Convention on Climate Change (UNFCCC) was born.

"Durban is the last real opportunity for countries to provide certainty on a future climate regime," says the green group WWF.

"The world's citizens are waiting for a clear signal about what countries will do in a second commitment period that will help save the planet and its people."

But such big-horizon rhetoric contrasts sharply with the low-key pragmatism that marks the climate process these days, a mood sharpened by financial crisis and austerity.

The new matrix is the Copenhagen Accord, which set down a target of limiting warming to two degrees Celsius (3.6 degrees Fahrenheit), formally adopted by the UN body at last year's talks in Cancun, Mexico.

No deadline or tools, however, have been set for achieving this goal beyond a voluntary roster of emission curbs.

"The pledges that are on the table right now, we reckon that maybe you get 60 percent of what needs to be done in order to stay below 2 C (3.6 F)," said Artur Runge-Metzger, the EU's top negotiator.

"If we move to a 4 C (7.2 F) world, the 2003 (European) summer, where we had this extraordinary heatwave in August, is an average summer in the 2040s and one of the cooler ones in the 2060s."

There were some 70,000 excess deaths across the continent that summer.

Deeply concerned by the widening "gigatonne gap," Europe wants Durban to set a roadmap towards a global pact by 2015, an idea shared by Australia, Norway and vulnerable small-island states.

But notions of where the roadmap would lead, and how long it might take to get there, vary.

The Durban talks start at the level of senior officials and end with environment ministers.

The meeting is also tasked with advancing a proposed Climate Green Fund, sketched in Copenhagen and launched in Cancun.

The goal is to ramp up provisions to at least 100 billion dollars a year by 2020 to help poor countries fight climate change and adapt to worsening floods, droughts and storms. But talks on the Fund's design have hit a roadblock, with objections raised by the United States and Saudi Arabia.