World on Brink of Deal to Combat Global Warming

The world was poised to agree a historic deal to tackle the threat of global warming last night, as a last-minute compromise appeared to have saved the UN climate talks. Yvo de Boer, the UN's top climate official, said countries were on the "brink of agreement" as the Bali discussions dragged on into the early hours.

The agreement, which lays the foundation for a new worldwide treaty to regulate greenhouse gas emissions, was expected to be finalized this morning.

The breakthrough follows two weeks of insults, arguments and threatened boycotts and trade sanctions, as nations wrangled over who should take responsibility for major cuts in carbon pollution.

Ban Ki-moon, UN secretary general, flew back to the talks late last night from East Timor to facilitate eleventh-hour negotiations. Campaigners and officials celebrated in the corridors of the convention center, as groups of ministers remained locked away in separate rooms to hammer out the final details.

De Boer said: "We are about to embark on something that for many years countries have been unwilling to embark on. Countries are treating this with great caution. They don't want to be led up the garden path."

The Bali agreement will trigger two years of intense negotiations over how to prevent a possible 4C rise in global temperatures this century, which would threaten the food and water supplies of billions of people and drive thousands of species to extinction. It commits countries to agree a new deal by 2009, which would come into force in 2013. The Kyoto Protocol, the existing global treaty on greenhouse gases, expires in 2012.

One of the last passages to be agreed - concerning targets for carbon reductions by rich countries - has in recent days proved the major roadblock to consensus. Europe was reported last night to have dropped its demands for a 25%-40% cut on 1990 levels by 2020, a proposal bitterly opposed by the US. Hilary Benn, the environment secretary, said: "There is a genuine will to do a deal [and] that's why they are still in there."

Campaigners commended moves in the Bali agreement to release funds to help poor countries adapt to the consequences of global warming and a pledge to protect forests in tropical countries. The director of Friends of the Earth, Tony Juniper, said: "There is still plenty to play for ... far more must be done over the next two years."

Kevin Anderson, a global warming expert at the Tyndall Center for Climate Change Research at Manchester University, said the new agreement would still struggle to constrain rising temperatures.