NEARLY 200 countries have struck a landmark grand bargain on climate change, agreeing for the first time to take action to curb greenhouse gas emissions.
After two weeks of grinding negotiations in Paris, nations signed off on the new deal that aims to stop the emission of heat-trapping gases into the atmosphere by the second half of the century.
The Paris agreement, which will come into effect in 2020, will require all countries, rather than just the wealthy ones, to tackle climate change.
The deal says the world will aim to stabilise global warming well below two degrees above pre-industrial levels, and less if possible.
Rousing applause and tears of joy filled the conference centre as the deal was passed in the conference centre on the northern outskirts of Paris.
It followed days of round-the-clock meetings, informal discussions and phone calls that dragged more than 24 hours past the scheduled end of the meeting on Friday afternoon.
Speaking to the conference on behalf of the umbrella group - a group of non-European industrialised nations - moments after the deal had passed, Australian Foreign Affairs Minister Julie Bishop said the world had produced a framework for all nations to play their part in securing "a safe and more prosperous world for future generations".
"Our work is here is done and now we can return home to implement the new global agreement," she said.
Ms Bishop said the targets in the agreement would require a "long-term transition to an emissions neutral and climate resilient world".
She told reporters the way the design of the agreement gave Australia "flexibility" to do more on climate change, with the spirit of the agreement encouraging countries to be more ambitious and to aim higher, with mind to their national circumstances.
The deal was not passed without a last-minute hiccup. As nations convened in the main plenary hall, the US was raising objections to the inclusion of the world "shall" instead of "should" in a reference to how developed countries take the lead on cutting emissions. It was a technical error, but posed serious legal issues for America.
Its attempt to change the word saw some African nations also try make more substantive changes to the text. But with harmony potentially unravelling they were dissuaded by a number of countries, including China.
At the same time, the Nicaraguan negotiator Paul Oquist tried to use the moment to also make changes. According to one senior source, US Secretary of State John Kerry phoned Nicaraguan President Daniel Ortega from the conference floor to get his man to stand down. Cuban President Raul Castro is also understood to have called Mr Ortega.
With ministers waiting nervously, the shall-should issue was resolved about an hour later and was included in a list of technical corrections that a UN official told the conference would be amended. Then the deal went through.
The delivery of a Paris agreement would have seemed far-fetched six years ago after the Copenhagen climate summit devolved into bitter bickering between powerful developed and developing nations as they struggled to find a successor to the 1997 Kyoto Protocol.
Those tensions flared again in Paris, but the deal that was brokered delivered on the main aims of the conference, and won near universal praise for the French government for its stewardship of the event.
US Secretary of State John Kerry said the moment had restored faith in multi-lateral negotiations.
"It's a victory for all of the planet and future generations," Mr Kerry said.
China's special representative on climate change, Xie Zhenhua, told the conference the world had adopted an equitable, balanced and ambitious agreement that sent a strong signal for green and low-carbon development.
The rebuilding of confidence to get to this moment in the United Nations climate negotiations has been slow, but has been aided by external factors including the plunging cost of non-fossil fuel energy and broadening commitments from business and other institutions to address the warming climate.
The Paris pact was also smoothed by a decision to allow countries to offer their own pledges to cut emissions, rather than have goals foisted on them through the UN process.
In the end, 187 nations came to the party with climate targets. But even if fulfilled, these targets will still leave the planet on the path to what scientists say would be dangerous global warming – estimated to be about 2.7 degrees above pre-industrial times.
Scientists warn that scale of increase would unlock more extreme weather and accelerate sea-level rises, among other impacts.
In a bid to spur governments to lift their ambition, the Paris accord includes a series of reviews of emissions targets that countries will need to undertake.
These reviews will start in 2020, two years after a collective assessment in 2018 of how the world is tracking on emissions and other parts of the agreement.
Reviews will then occur every five years. Under the deal countries will only be allowed to make targets more ambitious, not less.
While the agreement seeks to limit warming to "well below two degrees", it also asks countries to pursue efforts to keep temperatures below 1.5 degrees. This was the central demand in Paris from vulnerable nations, such as low-lying Pacific islands.
Temperatures this year have been on average one degree warmer than before the industrial era triggered a rapid rise in fossil fuel use and land clearing.
The agreement says greenhouse gas emissions should reach a peak as soon as possible and then slide rapidly, so the total amount of atmospheric pollution is brought to zero by the latter half of the century.
As part of asking the developing world to take on more action, industrialised nations agreed to deliver a minimum of $US100 billion ($139 billion) a year in public and private funding to help poorer nations cope with the impacts of climate change and cut their emissions. That figure will be reviewed upwards in 2025.
Other nations – in a move intended to rope in richer developing states such as China – are encouraged to make voluntary commitments.
The big division to overcome in the talks was that between industrialised nations, including the US and Australia, and the bigger emerging economies of China, India, Brazil and South Africa.
Industrialised countries wanted to break down a differentiation over what is expected of developed and developing nations that has existed under the UN climate talks since they were established in 1992. The large emerging economies sought to maintain some of that firewall.
At the same time, the new agreement had to factor in the circumstances of every other country in the world, from the least-developed African countries, to low-lying small island states, to forested South America nations.
Climate Institute chief executive John Connor said Australia's policies now had to match the aspirations set in Paris.
He said unless Australia adopted more aggressive policies, current targets would still leave it the highest per capita polluter in the G20 by 2030, alongside only Saudi Arabia, considered an obstructive force in the Paris talks.
"The time for piecemeal, unstable and short-term policy is over. The real work for Australia starts now," he said.
Greenpeace Australia chief executive David Ritter said the agreement meant "it's time for Prime Minister Malcolm Turnbull to shake off the climate policy hangover left by Tony Abbott and his band of climate deniers".
He said the government's support of the proposed Carmichael coal mine in Queensland was now clearly at odds with the global trend.
He said some big Australian companies were already picking up a market signal of a shift away from fossil fuels, particularly coal. "In Australia, we've seen the major banks backing away from fossil fuel investments".
Not everyone applauded the Paris deal. Tim Gore, Oxfam International's policy head, said the world's most powerful nations had used the summit to flex their muscles against weaker ones.
"We've really seen the kind of brutal nature of the power politics of these talks," Mr Gore said.
He said the reference to 1.5 degrees was "an important moral victory" but it may yet ring hollow without "a significant increase in action in the years ahead".