By Alister Doyle and Barbara Lewis
PARIS (Reuters) - French Foreign Minister Laurent Fabius presented a landmark global climate accord on Saturday, a "historic" measure for transforming the world's fossil fuel-driven economy within decades and turning the tide on global warming.
At the tail end of the hottest year on record and after four years of fraught U.N. talks often pitting the interests of rich nations against poor, imperilled island states against rising economic powerhouses, Fabius urged delegates from nearly 200 nations to support what he hopes will be a final draft.
The accord sets a sweeping long-term goal of eliminating net man-made greenhouse gas emissions this century. It also creates a system to encourage nations to make good on voluntary domestic efforts to curb emissions and provides billions more dollars to help poor nations cope with the transition to a greener economy.
"Our responsibility to history is immense," Fabius told thousands of officials, including President Francois Hollande and U.S. Secretary of State John Kerry, in the main hall of the conference venue on the outskirts of Paris.
"If we were to fail, how could we rebuild this hope?" he asked. "Our children would not understand or forgive us."
Negotiators are due to reconvene for discussion at 5:30 p.m. (1630 GMT), when they are widely expected to approve the agreement after two weeks of gruelling negotiations. The session was pushed back by nearly two hours, partly because OPEC nations needed more time to consider the long-term goal.
Calling it "ambitious and balanced", Fabius said the accord would mark a "historic turning point" in efforts to avert the potentially disastrous consequences of an overheated planet.
In some ways its success was assured before the summit began: 187 nations have submitted detailed national plans for how they will contain the rise in greenhouse gas emissions, commitments that are the core of the Paris deal.
While leaving each country to pursue those measures on its own, the fact that the world has signed on to a common vision and course of action - including a commitment to regularly review and step up their efforts - marks a breakthrough after years of bickering over how to move forward.
Officials hope a unified stance will be a powerful symbol for world citizens and a potent signal to the executives and investors they're counting on to spend trillions of dollars to replace coal-fired power with solar panels and windmills.
TOO MUCH, OR NOT ENOUGH?
While some climate change activists and U.S. Republicans will likely find fault with the accord - either for failing to take sufficiently drastic action, or for overreacting to an uncertain threat - many of the estimated 40,000 officials, academics and campaigners who set up camp on the outskirts of Paris say they see it as a long overdue turning point.
Six years after the previous climate summit in Copenhagen ended in failure and acrimony, the Paris pact appears to have rebuilt much of the trust required for a concerted global effort to combat climate change, delegates say.
"Whereas we left Copenhagen scared of what comes next, we'll leave Paris inspired to keep fighting," said David Turnbull, Director at Oil Change International, a research and advocacy organisation opposed to fossil fuel production.
A deal in Paris would mark a legacy-defining achievement for U.S. President Barack Obama, who has warned not to "condemn our children to a planet beyond their capacity to repair".
Most climate activists reacted positively, encouraged by long-term targets that were more ambitious than they expected, while warning it was only the first step of many.
From the outset, some have criticized the deal for setting too low a bar for success. Scientists warn that the envisaged national emissions cuts will not be enough to keep warming to less than 2 degrees Celsius (3.6 Fahrenheit) over pre-industrial times, the level scientists say is needed to avert the worst effects of warming such as flooding and severe droughts.
Unlike the Kyoto Protocol, the last major climate deal agreed in 1997, the Paris pact will also not be a fully legally binding treaty, something that would almost certainly fail to pass the U.S. Congress.
In the United States, many Republicans will see the pact as a dangerous endeavour that threatens to trade economic prosperity for an uncertain if greener future.
In central Paris, an estimated 10,000 demonstrators gathered near the Eiffel Tower, some chanting 'Climate justice now' while others sang and danced in apparent celebration.
After talks that extended into early morning, the draft text showed how officials had resolved the stickiest points. Hollande cautioned that the pact would not be "perfect for everyone", urging delegates to see the common need while reviewing key compromises that are certain to leave some nations unsatisfied.
"Faced with climate change our destinies are bound together," he said.
In a win for vulnerable low-lying nations who had portrayed the summit as the last chance to avoid the existential threat of rising seas, the agreement would set a more ambitious goal for limiting the rise in global temperatures to "well below" the 2 degrees Celsius threshold. Since 2010, the U.N. talks had referred only to the 2C figure.
"Our head is above water," Olai Uludong, ambassador on climate change for the Pacific island state of Palau, told Reuters, saying it would keep alive low-lying nations' hopes of limiting temperature rises to less than 1.5C (2.7F).
While scientists say pledges thus far could see global temperatures rise by as much as 3.7 degrees, the agreement also lays out a roadmap for checking up on progress. The first "stocktake" would occur in 2023, with further reviews every five years to steadily increase or "ratchet up" those measures.
It softened that requirement for countries with longer-term plans extending to 2030, such as China, which had resisted revisiting its goal before then.
And for the first time, the accord laid out a longer-term aspiration for reaching a peak in greenhouse emissions "as soon as possible" and achieving a balance between output of manmade greenhouse gases and absorption - by forests or the oceans - "by the second half of this century".
"If agreed and implemented, this means bringing down greenhouse-gas emissions to net zero within a few decades. It is in line with the scientific evidence we presented," said John Schellnhuber, Director of the Potsdam Institute for Climate Impact Research.
It also requires rich nations to maintain a $100 billion a year funding pledge beyond 2020, and use that figure as a "floor" for further support agreed by 2025, providing greater financial security to developing nations as they wean themselves away from coal-fired power.
(Reporting By Emmanuel Jarry, Bate Felix, Lesley Wroughton, Nina Chestney, Richard Valdmanis, Valerie Volcovici, Bruce Wallace and David Stanway; Editing by Jonathan Leff and David Evans)