The long-awaited UN summit on climate change is opening in the Danish capital Copenhagen, with delegates from 192 countries attending. Some scientists have described it as the most important conference the world has ever seen. About 100 leaders are to attend over the next two weeks. Developing countries are discussing whether to demand tougher emissions cuts than have been put forward so far. UN climate negotiator Yvo de Boer has said the talks were in excellent shape. On Sunday he told the BBC that many countries were now making pledges over curbing greenhouse gas emissions. "Never in 17 years of climate negotiations have so many different countries made so many pledges," he said. Mr de Boer said offers of finance for clean technology for poor countries were also coming through and talks were progressing on a long-term vision of massive carbon cuts by 2050. South Africa became the latest country to make an offer on cutting emissions - its first quantifiable target. On the eve of the summit it offered to cut by one-third the growth of its carbon emissions over the next decade - subject to getting more funding and technological help from wealthier countries. In July, the G8 bloc of industrialised countries and some major developing countries adopted a target of keeping the global average temperature rise since pre-industrial times to 2C. However now the G77/China bloc - which speaks on behalf of developing countries - is discussing whether to demand a much tougher target of 1.5C A number of African delegations are backing the argument made by small island states that 2C will bring major impacts to their countries. BBC environment correspondent Richard Black says this would raise a huge obstacle, because none of the industrialised countries have put forward emission cuts in the range that would be required to meet a 1.5C target. Meanwhile, a new poll commissioned by the BBC suggests that public concern over climate change is growing across the world. In the survey, by Globescan, 64% of people questioned said that they considered global warming a very serious problem - up 20% from a 1998 poll. To stress the importance of the summit, 56 newspapers in 45 countries are publishing the same editorial on Monday, warning that climate change will "ravage our planet" unless action is agreed, the London-based Guardian reported. The editorial - to be published in 20 languages - has been thrashed out by editors ahead of the Copenhagen talks, the newspaper said. "At the deal's heart must be a settlement between the rich world and the developing world," the editorial says. Environmental activists plan protests in Copenhagen and around the world on 12 December to encourage delegates to reach the strongest possible deal. Tens of thousands marched in London and other UK and European cities on Saturday. 'Long-term goal' Any agreement made at Copenhagen is intended to supplant the 1997 Kyoto Protocol on climate change. Targets set at Kyoto run out in 2012. Negotiations at Copenhagen begin on Monday and more than 100 world leaders will arrive next week to thrash out a deal. Speakers at the opening session will include Danish Prime Minister Lars Lokke Rasmussen and Rajendra Pachauri, head of the UN's panel of climate experts. World leaders who have pledged to attend include US President Barack Obama, UK Prime Minister Gordon Brown, French President Nicolas Sarkozy and Indian Prime Minister Manmohan Singh. The main areas for discussion include:

• Targets to curb greenhouse gas emissions, in particular by developed countries
• Financial support for mitigation of and adaptation to climate change by developing countries
• A carbon trading scheme aimed at ending the destruction of the world's forests by 2030

Outlining his ambitions for the summit, Mr de Boer said: "I think what we will see coming out of Copenhagen is a package of decisions that define a long-term goal. "Then, first of all, what will rich countries do to reduce their emissions. Secondly, what will major developing countries do to limit the growth of their emissions and thirdly prompt finance that will allow developing countries to adapt to the impacts of climate change." Meanwhile, research unveiled on Sunday suggests that less than one-third of money raised by major airlines in carbon trading schemes goes directly to reducing emissions. Carbon Retirement based its report on a sample of UN data. Under the system - set up by the Kyoto protocol - travellers pay for projects that offset emissions caused by their journey. Source: BBC