An "historic" international deal has been agreed by 195 countries in a bid to avoid dangerous climate change.
The agreement was gavelled through to huge cheers and applause at United Nations talks, following intense diplomatic efforts led by the French who hosted the summit in Paris just a few weeks after terror attacks there which killed 130 people.
The "Paris Agreement" is the world's first comprehensive climate accord, the core of which is legally binding and which commits all countries to take action to address global warming.
It includes a target to keep temperature rises "well below" 2C and commits to strive to curb increases to 1.5C, as well as a five-year review system to increase ambition on cutting emissions to meet the temperature goals.
It also differentiates between countries as to their responsibilities for action and provides finance for poor countries to deal with rising temperatures, both key asks for developing nations.
In spelling out the need for greenhouse gases to peak as soon as possible, and setting aims for the second half of the century that effectively mean the world will have to reach net zero emissions, the deal is being seen in many quarters as signalling the end of the fossil fuel era.
Some campaign groups warned the agreement is not strong enough to protect people, particularly in the most vulnerable countries, from the impacts of rising global temperatures, and to put the world on a path to a low carbon economy.
But it was widely - if cautiously in some quarters - welcomed by businesses, campaigners, scientists and analysts.
Prime Minister David Cameron said: "In striking this deal, the nations of the world have shown what unity, ambition and perseverance can do.
"Britain is already leading the way in work to cut emissions and help less developed countries cut theirs - and this global deal now means that the whole world has signed to play its part in halting climate change. It's a moment to remember and a huge step forward in helping to secure the future of our planet."
Energy and Climate Change Secretary Amber Rudd, who was part of the EU ministerial team negotiating the deal, said: "We have witnessed an important step forward, with an unprecedented number of countries agreeing to a deal to limit global temperature rises and avoid the worst impacts of climate change.
"This is vital for our long-term economic and global security. This deal will ensure all countries are held to account for their climate commitments and gives a clear signal to business to invest in the low carbon transition."
But the news of the deal prompted renewed calls for the UK Government, which has cut policies to support renewables, energy efficiency and clean technology in recent months, to ramp up its climate change efforts.
Labour leader Jeremy Corbyn said: "The Paris climate change agreement is historic in its ambition to take action against the worldwide threat of global warming.
" The challenge now is to turn the Paris agreement's fine words into the strong action the planet and its people need."
He accused the Prime Minister of failing to show the leadership the agreement demanded.
"David Cameron must now take his cue from Paris, reverse his Government's cuts to clean energy and put real investment in the green jobs of the future," he urged.
There were last-minute delays in getting the deal agreed, thought to be due to an issue of language in one part of the text, but eventually French foreign minister Laurent Fabius, who was chairing the talks, moved to adopt the agreement, said he saw no objections from any countries and it was passed.
Amid the euphoria that gripped the cavernous halls of Le Bourget conference centre in a northern suburb of Paris, there were warnings that the real work to tackle climate change is only just beginning.
Nevertheless the deal has backing from 195 countries, almost 190 of whom have submitted plans for the action they will take against climate change - with Venezuela bringing the total to 188 when it submitted its pledge on Saturday night after the deal was struck.
US secretary of state John Kerry described the agreement as a "tremendous victory" for all of the planet and for future generations.
He, like many others, paid tribute to the French, who are credited with delivering a master-class in diplomacy in steering the deal through tense and difficult negotiations to achieve agreement.