Copenhagen represents the best chance to get a deal on climate change that delivers a fall in emissions because the 'world is watching', Energy and Climate Change Secretary Ed Miliband said ahead of the start of the meetings next week.

'There is a real sense that the world is watching and that is a very, very important,' he told reporters in London on 3 December.

'The fact that the world is watching makes it both an important opportunity in the sense that people are going to have to step up to the plate but it also makes it an important challenge because we need to take advantage of this moment.'

He rejected calls to postpone the meeting in the hope of finding it easier to get a deal later next year. 'This is the best chance we have of getting a high ambition agreement because the world is watching.'

Mr Miliband said that the UK believed that the best outcome from Copenhagen would be a set of commitments from countries that added up to a peak in emissions in 2020.

'That will be a profound success as that has never been done before because emissions have just carried on rising after Kyoto and every other agreement.'

The two-week negotiations open on Monday 7 December in Copenhagen in the wake of a slew of new announcements. The last 10 days have seen major countries put numbers on mitigation on the table:

• US will reduce emissions by 17% below 2005 levels by 2020 - and cut emissions significantly by 2025 and 2030;
• China's first ever commitment to put a number on the table to reduce the carbon intensity of its economy by 40-45%;
• India's announcement of a reduction of its emission intensity by 20-25% by 2020 from the 2005 level; and
• Brazil announced 38-42% and Indonesia 26%.

Mr Miliband described those moves as 'a sign that the deadline and the raising of the stakes in my view is working. There’s a real sense that we need to get a deal done at Copenhagen. That is a positive thing.'

He reiterated that the UK's focus was on ensuring the most ambitious, comprehensive agreement we can at Copenhagen that should cover four key areas:

• Numbers on emissions reduction targets from developed countries;
• Action from developing countries to limit their emissions;
• Agreements on finance, technology, forestry and MRV (monitoring, reporting and verification); and
• A clear path from an agreement to a legally binding treaty within a matter of months

'The question is not just deal or no deal – it was what kind of deal we get.'

'I think we need to push for the highest ambition deal that we can get. So we want to try in the next two weeks to create a positive momentum towards that high ambition deal. It is about getting an agreement that is ambitious and consistent with the science and we think that’s that within reach.'

He dismissed as 'climate saboteurs' those who have used leaked emails from the Climatic research Unit at the University of East Anglia to claim that the scientific case for man-made climate change was not proved.

'There is a very widespread consensus on the science - something like 4,000 scientists who are part of the International Panel on Climate Change,' he said. 'I do think we have to beware of the climate saboteurs – the people who want to say that somehow this is in doubt  and who want to  cast aspersions on the whole process.'

'We are not going to take the easy way out. It would be profoundly irresponsible thing to do. The science is clear and settled and we will push on, as will other countries, to get an agreement that is consistent with the science.'

He said that Copenhagen needed to send a 'decisive signal' that it was moving toward a low carbon world. 'We will have taken decisions that will safeguard the world that our kids will inherit,' he said. 'The stakes are incredibly high and the longer we leave it and the more the costs will rise then the more danger we will store up for future generations.'