By Richard Valdmanis and Valerie Volcovici
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 turn 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 officials from nearly 200 nations to support what he hopes will be a final draft.
"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."
Barring any last-minute objections as negotiators pore over the final text for the next few hours, they will reconvene at around 1545 local time (1445 GMT) to approve the agreement, a major breakthrough in global efforts to avert the potentially disastrous consequences of an overheated planet.
Calling it an "ambitious and balanced" agreement, Fabius said it would mark a "historic turning point" for the world. Hollande cautioned that the pact would not be "perfect for everyone", urging delegates to see the common need.
"Faced with climate change our destinies are bound together," he said.
In talks that lasted into the early morning, officials appeared to have resolved the final sticking points, and Fabius highlighted the key points: a more ambitious goal for limiting the rise in global temperatures to less than 2 degrees Celsius; a $100 billion a year floor for funding developing nations beyond 2020; and a five-year cycle for reviewing national pledges to take action on greenhouse gas emissions.
Prior to the session, China's top negotiator Gao Feng said there "there is hope today" for a final pact, while Marshall Islands Foreign Minister Tony De Brum told Reuters: "I think we're done here."
A deal, if finalised, would be a powerful symbol to world citizens and a potent signal to investors - for the first time in over two decades, both rich and poor nations will agree to a common vision for curbing greenhouse gas emissions, and a roadmap for ending two centuries of fossil fuel dominance.
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 and environmentalists 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.
NOT ENOUGH, OR TOO MUCH?
From the outset, critics have said the emerging deal had serious weaknesses, most prominently the fact that envisaged 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 including severe droughts and rising sea levels.
Unlike the Kyoto Protocol, the last major climate deal agreed in 1997, the Paris pact will also not be a legally binding treaty, something that would almost certainly fail to pass the U.S. Congress. Instead, it will be largely up to each nation to pursue greener growth in its own way, making good on detailed pledges submitted ahead of the two-week summit.
And 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.
Still, by charting a common course, officials hope executives and investors will be more willing to spend trillions of dollars to replace coal-fired power with solar panels and windmills.
"It will be up to business, consumers, citizens and particularly investors to finish the job," said Hans Joachim Schellnhuber, director of the Potsdam Institute for Climate Impact Research.
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".
Leaders of vulnerable low-lying countries - who brought together more than 100 nations in a "high ambition coalition" at the talks, striving for the strongest possible language - have portrayed the Paris talks as the last chance to avoid the catastrophic consequences of rising temperatures.
Without joining together for immediate action, they had warned, greenhouse gas emissions would be certain to push the planet's ecosystem beyond the 2C tipping point. They appeared to have carried the day, as Fabius said the text would seek to keep the rise to "well below" 2 degrees Celsius and if possible to limit global warming to 1.5 degrees.
While scientists say national pledges thus far are still too little to prevent that happening, the agreement should set out a roadmap for steadily increasing or "ratcheting up" those measures in order to head off calamity. Fabius said those efforts would occur every five years.
President Xi Jinping has promised that carbon dioxide emissions from China's rapidly developing economy will start falling from around 2030, and does not want to revisit the target. Delegates said China had also reasserted demands that developed nations do far more to curb greenhouse gas emissions, mostly the result of burning coal, gas and oil.
A final deal is expected to provide developing nations greater financial security as they wean themselves away from coal-fired power, and also suffer the financial consequences of a warming climate on the earth's flora and fauna.
It will set a "floor" for such funding at $100 billion a year, Fabius said, building on a 2009 pledge to provide at least that sum by 2020.
(Reporting By Emmanuel Jarry, Bate Felix, Lesley Wroughton, Nina Chestney and David Stanway; Editing by Jonathan Leff, Mark Heinrich and David Evans)