The long-awaited Copenhagen Climate Change Conference will have the eyes of the world set on the Danish capital between December 7 and 18 2009, with delegates from 192 countries trying to come up with answers to and commitments on the planet's climate issues.
The conference has been described by some scientists as the most important the world has ever seen, the BBC said.
Security is tight as organisers expect 15 000 delegates and 100 world leaders to attend over the next two weeks.
On the eve of the summit, UN chief climate negotiator Yvo de Boer said the talks were in excellent shape. He told the BBC that many countries were now making pledges to curb greenhouse gas emissions.
"Never in 17 years of climate negotiations have so many different countries made so many pledges. It is unprecedented," de Boer was quoted by the BBC as saying.
According to him, offers to finance clean technology for poor countries were also coming through and talks were progressing on a long-term vision of massive carbon cuts by 2050.
Bulgaria was one of the nine newest European Union members states, who helped the rest of the block come up with a joint position ahead of the summit.
The nine Eastern European countries managed to negotiate better terms for themselves in the joint EU position on providing financial aid to developing countries on carbon emissions.
Bulgarian Prime Minister Boiko Borissov said "the decision guarantees that we will not be donors to countries such as China, India, Brazil and Russia."