The deal should lead to better protection for tropical forests
Delegates at the UN summit in Bali have agreed a deal on curbing climate change after days of bitter wrangling.
Agreement was reached after a U-turn from the US, which had wanted firmer commitments from developing countries.
Environment groups said they were disappointed by the lack of firm targets for reducing emissions.
The "Bali roadmap" initiates a two-year process of negotiations designed to agree a new set of emissions targets to replace those in the Kyoto Protocol.
The EU had pressed for a commitment that industrialised nations should commit to cuts of 25-40% by 2020, a bid that was implacably opposed by a bloc containing the US, Canada and Japan.
The final text does not mention specific emissions targets, but does acknowledge that "deep cuts in global emissions will be required to achieve the ultimate objective" of avoiding dangerous climate change.
It also says that a delay in reducing emissions will make severe climate impacts more likely.
'Spirit of flexibility'
"This is a real breakthrough, a real opportunity for the international community to successfully fight climate change," said Indonesian Environment Minister Rachmat Witoelar, who served as conference president, at the conclusion of the talks.
UN Secretary General Ban Ki-moon said he appreciated "the spirit of flexibility" shown by key delegations - and was aware that "there is divide of position between and among countries".
The US was the principal focus of opposition from activists
"But as this global warming is an issue which affects the whole humanity, whole planet earth, we must have co-ordinated and concerted efforts to address this issue," Mr Ban said.
In London, UK Prime Minister Gordon Brown declared: "This agreement is a vital step forward for the whole world.
"The Bali roadmap agreed today is just the first step. Now begins the hardest work, as all nations work towards a deal in Copenhagen in 2009 to address the defining challenge of our time."
Environmental groups and some delegates have criticised the draft as being weak and a missed opportunity.
"This deal is very disappointing," said Tony Juniper of Friends of the Earth.
"We said we needed a roadmap, but this conference has failed to give us a clear destination."
As talks overran their scheduled close by more than a day, delegates from the EU, US and G-77/China embarked with UN officials on a series of behind-the-scenes consultations aiming to break the remaining deadlock.
The EU and US agreed to drop binding targets; then the EU and China agreed to soften language on commitments from developing countries.
With delegates anxious to make a deal and catch aeroplanes home, the US delegation announced it could not support the amended text.
A chorus of boos rang out. And a member of Papua New Guinea's delegation told the US: "If you're not willing to lead, please get out of the way."
Shortly after, the US delegation announced it would support the revised text after all.
There were a number of emotional moments in the conference hall - the UN's top climate official Yvo de Boer in tears after being accused by China of procedural irregularities, and cheers and hugs when the US indicated its acceptance.
On the road
The document coming out of the meeting, the "Bali roadmap", contains text on emissions cuts, the transfer of clean technology to developing countries, halting deforestation and helping poorer nations protect their economies and societies against impacts of climate change such as rising sea levels and falling crop yields.
The roadmap sets the parameters and aims for a further set of negotiations to be finalised by the 2009 UN climate conference, to be held in Denmark.
By that stage, parties should have agreed on a comprehensive plan for curbing global warming and adapting to its impacts.
This will include:
- emissions targets for industrialised countries, possibly but not necessarily binding
- some softer form of targets or ambitions for major developing countries
- mechanisms for leveraging funds from carbon trading to fund adaptation projects
Earlier, consensus was reached on the principle of rewarding poorer countries to protect their forests.
This is widely acknowledged as the cheapest single way of curbing climate change, and brings benefits in other environmental areas such as biodiversity and fresh water conservation.
Delegates agreed on a framework that could allow richer nations and companies to earn "carbon credits" by paying for forest protection in developing countries.
"We need to find a new mechanism that values standing forests," said Andrew Mitchell, executive director of the Global Canopy Programme, an alliance of research institutions.
"Ultimately, if this does its job, [deforestation] goes down to nothing."
Mr Mitchell said the only feasible source of sufficient funds was a global carbon market.
But many economists believe mandatory emissions targets are needed to create a meaningful global market.