'The climate is changing much faster than expected. ... This underlines the urgent need to reach a global, ambitious and comprehensive agreement in Copenhagen,' the joint statement said.

'The world has a fever: we need to stop the acting and start the action,' said Swedish Prime Minister Fredrik Reinfeldt, whose country currently holds the EU's rotating presidency.

With just 80 days to go until the Copenhagen summit, there are 2,500 negotiating points that world powers still have to agree, said Reinfeldt, who will represent the EU in the Danish capital.

EU officials say that it will only be possible to reach a deal if the United States, historically the world's largest polluter, agrees to legally binding greenhouse-gas emission targets.

But US leaders have long maintained that they will only agree to such caps if the major developing powers pledge to brake the growth of their own soaring greenhouse-gas emissions.

The EU is therefore keen to bring the two sides by proposing a 'global key', which would define rich and poor nations' responsibilities and calculate how much money each country should pay to the worldwide fight against climate change.

'You cannot move forward unless the world moves together. We have to bring in not just the old G8 (group of the world's leading developed economies): this involves all the countries of the world,' British Prime Minister Gordon Brown said.

A week ago, the commission said that European taxpayers should pay from 2 billion to 15 billion euros per year toward the global fight against climate change by 2020, depending on whether the bill is calculated according to the EU's current wealth or greenhouse gas emissions.

Using the same formulae, the US would pay up to 12.6 billion euros per year, Japan 4.4 billion euros, China 7.9 billion euros and India 2 billion euros.