BANGKOK, Thailand - Climate talks kicked off in Bangkok Monday with the United Nations urging nations to break the deadlock over a global warming deal that is supposed to be finalized in just 70 days time, and warning that failure to act would leave future generations fighting for survival.

Negotiations on a new UN climate pact have been bogged down by a broad unwillingness to commit to firm emissions targets, and a refusal by developing countries to sign a deal until the West guarantees tens of billions of dollars in financial assistance -- something rich countries have so far refused to do.

"Time is not just pressing. It has almost run out," UN climate chief Yvo de Boer said, with a clock nearby showing there were 70 days until world leaders are scheduled to meet in Copenhagen to finalize a pact. "If we don't realize Plan A, the future will hold us to account," he said.

The conference is being attended by delegates from 180 nations. Some pointed to the tropical storm that tore through the Philippines over the weekend, leaving scores dead, as a glimpse into the kind of turbulent weather that could be unleashed by global warming.

"We are asking the negotiators to look outside these walls. They should realize that it is the people's lives at stake," said Dinah Fuentesfina, a Philippine activist from the Global Campaign for Climate Action Asia who was in Manila when the storm struck Saturday.

Connie Hedegaard, the Danish minister for climate and energy whose country will host the talks in December, told delegates the world was watching and urged them to build on the momentum that came out of last week's UN climate summit where 100 world leaders pledged their support for an agreement.

At the New York summit, President Barack Obama and China's president -- whose countries are the world's two biggest emitters, each accounting for about 20 per cent of greenhouse gas pollution -- both vowed tough measures to combat climate change.

President Hu Jintao said China would generate 15 per cent of its energy from renewable sources within a decade, and for the first time pledged to reduce the rate by which its carbon emissions rise. He did not give specific targets.

Japan's new prime minister, Yukio Hatoyama, whose nation generates more than 4 per cent of the world's greenhouse gases, pledged to seek a 25 per cent cut in emissions from 1990 levels by 2020.

The United States has offered much lower targets so far, with a House of Representatives bill proposing to reduce emissions by 17 per cent from 2005 levels -- or about 4 per cent below 1990 levels -- by 2020. The Senate has yet to take up the climate bill.

"Citizens across the world call for action on climate change," Hedegaard said. "We must heed that call. If we fail, we will all face dire consequences."

The two weeks of UN climate talks in the Thai capital, the second to last meeting before Copenhagen, are drawing some 1,500 delegates from 180 countries who will be tasked with boiling down an unwieldy, 200-page draft agreement to something more manageable.

Most countries agree that temperature increases should be limited to two degrees Celsius above preindustrial levels of about 150 years ago -- a level believed necessary to avoid the worst impacts of climate change. But so far, there is no consensus on how to do that.

Most industrialized nations have offered emissions cuts of 15 per cent to 23 per cent below 1990 levels by 2020, falling short of the 25 per cent to 40 per cent cuts scientists and activists say are needed to keep temperature increases below two degrees Celsius.

De Boer insisted a deal could still be reached in Copenhagen but divisions were clear on the first day as poor countries called for even deeper emissions cuts from rich nations.

"Emission reductions of at least 40 per cent or 45 per cent below the 1990 baseline by developed countries are required and must be announced without further delay," the Indian delegation said in a statement.

Sudan's Lumumba Di-Aping, speaking for the Group of 77 developing countries and China, said it was just as important that developed countries financially help poor nations adapt to the impacts of climate change and develop greener economies.

"Finance and technology are central to achieving a just and equitable deal," Di-Aping said. "Without financing, there is no mitigation and no adaptation and therefore there would be no deal. It is as simple as that."

But the United States shot back that developing countries would have to do their part -- short of binding targets -- to reduce greenhouse gas emissions and for the first time agree to a system that would monitor and verify their promised actions.

Jonathan Pershing, the chief U.S. negotiator at the talks, noted that Brazil talked about actions to reduce deforestation and there have been proposals from China and India on solar power, renewable energy and energy efficiency.

"We expect them to stand behind those actions the way we would stand behind ours and reflect them in this international agreement," he said.