More than 190 countries have struck an agreement at the latest round of UN climate talks that puts efforts to secure a new international deal to tackle global warming back on track.
The talks in Cancun, Mexico, were the latest attempt to make progress towards a new global deal on tackling climate change, after last year's meeting in Copenhagen failed amid chaotic scenes to secure a new legally-binding treaty on cutting emissions, instead delivering only a weak voluntary accord.
At the end of two weeks of talks in Mexico, government ministers and officials agreed a deal which Climate Change Secretary Chris Huhne described as a "serious package" of measures.
He acknowledged the agreement did not give everybody everything they wanted and would still require work towards a final deal at a meeting next year in Durban, South Africa.
Environmental campaigners said it threw a lifeline to efforts to get a deal to tackle climate change but there was still much work to do, in particular to close the "gigatonne gap" between the greenhouse emissions cuts countries have pledged and the reductions needed to limit temperature rises to no more than 2C.
The agreement acknowledges the need to keep temperature rises to 2C and brings non-binding emissions cuts pledges made under the voluntary Copenhagen Accord, hammered out in the dying hours of last year's conference, into the UN process.
It also includes an agreement to set up a green climate fund as part of efforts to deliver 100 billion US dollars (£60 billion) a year by 2020 to poor countries to help them cope with the impacts of global warming and develop without polluting.
It includes a scheme to provide financial support for countries to preserve their forests, in a bid to combat deforestation which accounts for almost a fifth of global annual emissions, and makes progress on how countries' actions are going to be monitored and verified..
Earlier progress had been held up by the major stumbling block of what is to be done about the existing climate treaty, Kyoto protocol, and how major emitters such as the US and China should be included in a future deal.
But in scenes in the final hours that were in sharp contrast to last year's angry debates between countries in Copenhagen, the Mexican president of the conference Patricia Espinosa received two standing ovations in the meeting for her work to achieve agreement, with the Indian delegation describing her as a goddess.
Representatives from country after country acknowledged the agreement was not perfect, but that they supported it as progress towards a final deal - although Bolivia hit out at the proposals, likening them to genocide.
Friends of the Earth's international climate campaigner Asad Rehman described the Cancun agreement as weak and ineffective - but said it gave the world a "small and fragile lifeline".
And he warned: ""The emissions cuts on the table could still lead to a global temperature increase of up to five degrees which would be catastrophic for hundreds of millions of the world's poorest people."
Keith Allott, head of climate change at WWF-UK, said: "After Copenhagen it was hoped that Cancun could establish a platform for progressing action on climate change.
"Despite some last minute hiccups, countries leave here with a renewed sense of goodwill and some sense of purpose," he said.
But he said a lot of work had to be done to make sure the agreements achieved in Cancun were built on next year.
"The UK and EU must not squander this chance - they need to champion much more ambitious action to cut emissions and close the 'gigatonne gap," he urged
And he said: "Governments backed a new global "green fund". The UK needs to drive this forward by backing new sources of finance, such as levies on international aviation and shipping."
Friends of the Earth International Climate Campaigner Asad Rehman said: "The world needed strong and determined action to tackle climate change in Cancun - the outcome is a weak and ineffective agreement but at least it gives us a small and fragile lifeline.
"Russia, Japan and the US, backed by powerful vested interests, have pursued a selfish agenda which has opened the door to a hazardous system where emissions targets would be decided on the whim of politicians, rather than by science.
"The emissions cuts on the table could still lead to a global temperature increase of up to five degrees which would be catastrophic for hundreds of millions of the world's poorest people."
Alex Farrow, Co-director of the UK Youth Climate Coalition, said: "Today's progress gives young people across the world hope. This is the beginning of a common climate path. These outcomes put us one step closer to the cleaner, fairer future that young people across the world dream of.
"UK youth made hundreds of phone calls and generated thousands of tweets to persuade Chris Huhne to stay in Cancun for the climate talks. Our hard work paid off, as Huhne stayed to continue his key role in bringing parties together."
Cafod's head of policy Gwen Barry said: "Cancun has shown people whose lives depend on these negotiations that the world is serious about preventing devastating climate change. The gains made here in Mexico lay the foundations for action towards a legally binding agreement that could safeguard the future for our children and grandchildren.
"It is a credit to the Mexican presidency of the COP that they created the political space for meaningful negotiation. After the damaging adversarial tone of Copenhagen and Tianjin they have offered us glimpses of a political dynamic that could successfully tackle climate change. The collective spirit of multi-lateralism that filled the last hours of Cancun engendered a level of compromise that saw even recalcitrant nations find room for flexibility.
"But Japan, the US, Russia and Canada - and any nation that did not come to Cancun with ambitious mandates - must be reminded that when the present economic crisis has ended, climate change will still be gathering pace. And with each year that passes without a globally binding agreement to cut emissions and finance poor countries' needs to adapt to climate change and develop low-carbon economies, the impacts will become more and more severe.
Bolivia repeatedly opposed attempts to pass the agreement, but it was gavelled through in the early hours of the morning in Mexico to rapturous applause from delegates.
Greenpeace International Climate Policy Director Wendel Trio said: "Cancun may have saved the process but it did not yet save the climate.
"Some called the process dead but governments have shown that they can cooperate and can move forward to achieve a global deal."
"Cancun has delivered the momentum - but we haven't arrived there yet.
"In Durban we need a global deal that helps countries build a green economy and that holds polluters accountable."
Mr Huhne said the agreement secured today got the show back on the road and gave a new sense of momentum going forward to Durban - though he said it was too early to say what could be achieved in South Africa.
He said the package was the first to spell out the need for emissions to peak and decline as soon as possible, to stay within 2C temperature rises and to assess whether the level of emissions cuts needed to be higher.
"What this does is show there's a real consensus internationally, a growing consensus from places a year ago you wouldn't expect, such as China and India, that we do have to go down this path to a low carbon economy and it's the road to prosperity," he said.
He also said today's deal made it more likely the EU would move to a more ambitious target to cut emissions by 30% on 1990 levels and predicted that more countries in the European Union would back the move from 20% up to 30% cuts shortly.
The UK has already said it wants to go to the higher target to stimulate green business.
And he said the international progress made it easier for the Government in the UK to follow the science in its climate change actions.
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