Countries agreed a deal today to push for a new climate treaty, salvaging the latest round of United Nations climate talks from the brink of collapse.
The UK's Climate Change Secretary Chris Huhne hailed the deal, finally struck in the early hours after talks had overrun by a day and a half, as a "significant step forward" which would deliver a global, overarching legal agreement to cut emissions.
And he said it sent a strong signal to businesses and investors about moving to a low carbon economy.
But environmental groups said negotiators had failed to show the ambition necessary to cut emissions by levels that would limit global temperature rises to no more than 2C and avoid "dangerous" climate change.
The EU had come to the talks in Durban, South Africa, calling for a mandate to negotiate a new legally binding treaty on global warming by 2015, covering all major emitters, in return for the bloc signing up to a second period of emissions cuts under the existing Kyoto climate deal.
But in a surprise move yesterday evening, options for the new legal deal had been watered down to add a "legal outcome" to the existing possibilities of a "protocol or another legal instrument" - the language which was used in the mandate for negotiating the Kyoto Protocol.
European ministers warned they could not accept the weakened deal, but India led the countries pushing for it, claiming they could not sign up to negotiate a legally-binding deal without knowing what would be in it or if it would be fair to poorer countries.
The deal was reached after the South African president of the talks urged the EU and India to go "into a huddle" in the middle of the conference hall in the early hours of this morning, in a bid to work out language both sides were happy with.
A compromise, suggested by the Brazilian delegation, saw the EU and Indians agree to a road map which commits countries to negotiating a protocol, another legal instrument or an "agreed outcome with legal force".
The treaty will be negotiated by 2015 and coming into force from 2020.
The deal also paves the way for action to address the "emissions gap" between the voluntary emissions cuts countries have already pledged and the reductions experts say are needed to effectively tackle climate change.
Mr Huhne insisted the agreement on the legal language was not "a fudge" and said that while the EU had not secured everything it wanted from the talks, it was a great diplomatic success for the bloc.
He said: "What we have got is a very significant step forward because we've got a road map leading to a global overarching legal agreement, which is exactly what we wanted, we've got a timeline on it.
"And we've got a very clear process for dealing with the emissions gap in the interim."
He added: "We've managed to put this on the map and bring all the major emitters like the US, India and China into a road map which will secure an overarching global deal."
While European leaders have been in turmoil over the Eurozone crisis in Brussels this week, Mr Huhne said that, in Durban, EU countries had all been "singing from the same hymn sheet" and when the bloc was united it was "quite formidable".
He paid tribute to countries such as China for the work they were doing to cut emissions on the ground.
And he said: "This is coming together in an overall international framework that gives business greater assurance about the future and investors greater assurance about the rate of returns they're going to get, and stop us locking in a whole generation of high carbon technology that might other happen."
Michael Jacobs, who was former prime minister Gordon Brown's climate adviser and now visiting professor at the Grantham Research Institute of Climate Change and the Environment at LSE, said business was looking for signals that governments were serious about low carbon policy - and that policies would be sustained.
"By acknowledging that current emissions targets are inadequate and must be raised, and by re-establishing the goal of a legal treaty, this agreement should help build such confidence," he said.
But environmental groups criticised the deal, finally agreed as the sun rose on the third night of all-night talks among negotiators and ministers, for a lack of ambition in cutting the greenhouse gas emissions which drive global warming.
Keith Allott, Head of Climate Change at WWF-UK, said: "Governments have salvaged a path forward for negotiations, but we must be under no illusion - the outcome of Durban leaves us with the prospect of being legally bound to a world of 4C warming.
"This would be catastrophic for people and the natural world. Governments have spent crucial days focused on a handful of specific words in the negotiating text, but have paid little heed to repeated warnings from the scientific community that much stronger, urgent action is needed to cut emissions."
He welcomed the EU's role in a "high ambition coalition" of countries including the small island states and some of the poorest nations in the world, but urged Europe to show leadership by increasing its promise to cut emissions by 20% by 2020 to 30%.
Greenpeace International's executive director Kumi Naidoo said: "Right now the global climate regime amounts to nothing more than a voluntary deal that's put off for a decade.
"This could take us over the two degree threshold where we pass from danger to potential catastrophe."
Also agreed at the Durban talks was the establishment of a green climate fund to channel billions of pounds to poor countries to help them cope with impacts of global warming such as floods and drought - but no sources of money were found.
Rich countries have pledged 100 billion dollars (£64 billion) a year by 2020 for developing countries to deal with climate change and develop without polluting.
Campaigners say the funding to help some of the world's most vulnerable people is particularly important if emissions reductions in the next decade and action after 2020 are not sufficient to keep long term temperature rises to no more than 2C.
Celine Charveriat, director of campaigns and advocacy for Oxfam said: "We cannot allow the Green Climate Fund to wither on the vine.
"Governments must identify significant and predictable sources of money for the Fund without delay, such as a tiny tax on financial transactions and a fee on emissions from international shipping."
Mohamed Adow of Christian Aid said: "Action against climate change in 2020 will come a decade too late for poor people on the front line - they urgently need it now.
"Their lives are already ravaged by floods, droughts, failed rains, deadly storms, hunger and disease and we know that these disasters will get worse and more frequent as climate change bites."
Friends of the Earth's executive director Andy Atkins said: "The UN climate change process is still alive - but this empty shell of a plan leaves the planet hurtling towards catastrophic climate change.
"If Durban is to be a historic stepping stone towards success the world must urgently agree ambitious targets to slash emissions.
"Millions of the poorest people around the globe are already facing the impacts of climate change - countries like the US who have done most to create this crisis must now take the lead in tackling it.
"Decisive action to tackle climate change would slash fuel bills, create much-needed jobs and help people in poorer countries gain access to clean energy."
The World Development Movement said the outcome of the talks was a "spectacular failure".
Murray Worthy, the organisation's policy officer, said: "Developed countries have behaved shamefully, blocking meaningful progress on tackling climate change.
"They have refused to acknowledge their historical responsibility for the crisis, either by agreeing to reduce their emissions or by providing finance to help developing countries deal with climate change.
"These talks have been held hostage by the EU. It seems EU countries came to Durban to impose a deal, not negotiate one.
"The spectacular failure to achieve an outcome on the most urgent issues puts the world on course for devastating climate change, condemning those least responsible to greater hunger, poverty and ultimately, death."