Minutes after passing the Kyoto resolution on Saturday, ministers also agreed to launch new, open-ended world talks on ways to fight global warming, overcoming objections by the United States, which had resisted taking part in broader discussions.
The Montreal meeting had dragged on till nearly dawn on Saturday, in part delayed by last-minute Russian objections.
"This has been one of the most productive UN climate change conferences ever. This plan sets the course for future action on climate change," said Richard Kinley, acting head of the UN Climate Change Secretariat.
Environment activists cheered, hugged and some even cried after the delegates passed what they saw as historic decisions tackling climate change.
"There were many potential points at this meeting when the world could have given up due to the tactics of the Bush administration and others but it did not," said Jennifer Morgan, climate change expert at WWF.
"And we must count on this resolve moving forward to bring the much deeper cuts in emissions in order to avoid the very devastating impacts of climate change," she said.
The 20-hour talks left delegates
exhausted and emotional
The Montreal talks followed a twin track, one pursuing negotiations to advance Kyoto and the other under the broader UN Framework Convention on Climate Convention, Kyoto's parent treaty.
The US, the world's largest emitter of greenhouse gases, and Australia have refused to ratify Kyoto but are members of the parent treaty and Washington had initially refused to support a broader dialogue, fearing it might lead binding commitments for cutting emissions.
The Kyoto decision urges rich nations to decide new commitments beyond 2012 as early as possible without setting a detailed timetable.
Under Kyoto, about 40 industrialised nations have to cut their emissions by an average of 5.2% below 1990 levels by 2008-12.
But developing countries, such as China and India, have no targets under Kyoto and say that rich industrial states have to take the lead in cutting emissions after fuelling their economies with coal, oil and gas since the Industrial Revolution.
The agreement on a Kyoto renewal road map would give members seven years to negotiate and ratify accords by the time the first phase ends in 2012. Most countries agree that deeper cuts will be needed to avoid climate chaos in coming decades.
Global warming is widely blamed on a build-up of gases from burning fossil fuels in power plants, autos and factories.
"At 6.17 this morning, he brought down the gavel on a set of agreements that may well save the planet"
Sierra Club of Canada
With the talks over, a huge sigh of relief swept through the vast conference hall after a 20-hour session that left delegates exhausted and a little emotional.
"We are delighted," said Margaret Beckett, Environment Secretary for Britain, currently holding the rotating EU Presidency. "It's the fruit of a year's work for us."
Some environmentalists said the Montreal meeting would have profound consequences for humanity.
"At 6.17 this morning, he brought down the gavel on a set of agreements that may well save the planet," Elizabeth May of the Sierra Club of Canada said, referring to Canadian conference chairman Stephane Dion, Canada's environment minister.