At the formal start of ministerial level talks at the 12-day conference the chairwoman and former Danish climate minister, Connie Hedegaard, said Tuesday that the United Nations summit risks failure unless delegates enter into the spirit of compromise.

"Success is still within reach. But as (chairwoman), I must also warn you: 'We can fail'," she said, holding out a stark warning as the final phase of negotiations began.

"We can't risk failure. No one here can carry that responsibility. That means that the key word for the next two days must be compromise," Hedegaard added.

UN chief's plea

In an effort to press home the urgency of the issue, UN Secretary General Ban Ki-moon described the climate summit in Copenhagen as a pivotal time in history. He warned world leaders that the world has turned to them to "seal the deal."

"This (is a) defining moment in history," the UN chief said Tuesday. "We have a chance, a real chance, to change the course of history.”

"We know what we must do. We know what the world expects,” Ban said, adding: “Our job here and now is to seal the deal, a deal in our common interest."

Ban said that he wanted to see "a deal that reduces greenhouse-gas emissions, that protects the most vulnerable, that ushers in a new era of clean development and green growth for all."

Targets for reductions in emissions had to be more ambitious and finance was central to any agreement, he said, touching upon some of the key divisive issues.

"Financing will be key, particularly in helping the poorest countries," he added.

Ban was among the dignitaries addressing nearly 200 national delegations at a ceremony marking the start of high-level talks among environment ministers. So far, discussions aimed at slowing global warming had been conducted by bureaucrats.

Merkel voices concern

German Chancellor Angela Merkel has also voiced concern about the pace of climate talks in Copenhagen and prospects of success.

"I will not hide the fact that I am somewhat nervous whether we will manage to achieve everything," she said when asked about her hopes for reaching a deal by the end of the week on curbing CO2 output and slowing global warming.

Merkel urged developed and developing nations to make a "constructive contribution" to an agreement, highlighting the deep divisions between rich and poor nations at the climate summit.

"We know that time is running out," the German chancellor told reporters after talks with Indonesian President Susilo Bambang Yudhoyono in Berlin on Tuesday.

Merkel, who says Germany will commit to reducing greenhouse emissions by 30 percent from 1990 levels by 2020 or even 40 percent if others agree to steep cuts, will be in Copenhagen with world leaders for the last two days on Thursday and Friday.

After meeting with Merkel, Yudhoyono called for developing countries to increase their pledges. "I am convinced that the developing countries must give more and do more to jointly achieve the international targets," he said.

Crucial issues still unresolved

With less than four days left before the end of the marathon conference, and the most crucial issues still unresolved, officials urged the parties to set their differences aside and work for an ambitious deal.

UN's climate chief, Yvo de Boer, said that "there is still an enormous amount of work and ground that needs to be covered."

While emission targets and financial aid to poorer nations are still two of the biggest obstacles to an ambitious political deal, there are several other fault lines too.

The questions of who should manage and hand out the billions of dollars of aid money that poor nations need in order to mitigate and adapt to global warming as well as how to verify and enforce emissions targets set by developing countries are among sticky issues.

Some developing nations say handing over control on those issues to the developed world would smack of neo-colonialism.

rb/AFP/dpa
Editor: Trinity Hartman