Representatives of 191 countries have been invited to meet in Copenhagen from Dec. 7 to attempt to reach a global consensus on tackling climate change. So far 67 heads of state have confirmed their attendance at the UN conference.

In the run-up to the event, the main players have revealed their stated objectives for the reduction of greenhouse gas emissions.

China links reducing CO2 to economic growth

China, one of the world's biggest polluters, has always refused to impose fixed targets for emissions reduction in order to protect its economic growth.

But now China has unveiled its first firm target to curb greenhouse gas emissions, laying out a carbon intensity goal (the amount of carbon dioxide emitted for each unit of economic output) that premier Wen Jiabao will take to the climate talks as his government's central commitment.

The carbon intensity goal highlights China's commitment both to the environment and to continued economic growth.

Obama balances international ambition with domestic restraints

The United States has the dubious honour of being the world's other top polluter.

In a break with his predecessor George W. Bush, Barack Obama takes the issue of man-made global warming seriously. But Obama needs to reconcile the expectations of the international community with realities at home.

Obama's stated objectives are to reduce overall greenhouse gas emissions by 17% by 2020, then 30% by 2025 and 42% by 2030 (based on 2005 levels).

But this needs to be approved by Congress which will be responsible for passing climate legislation. The US House of Representatives only narrowly approved these figures in June and the Senate has only just begun looking at them. The Senate is likely to be cautious as sweeping reductions in emissions will have a significant impact on US industrial interests.

EU the standard bearer?

The EU is keen to be seen as a standard bearer for the reduction of greenhouse gasses. At the end of October the EU identified that developing nations need help to the tune of 100 billion euros per year to reduce their emissions - but failed to agree on how this aid could be achieved.

EU countries have pledged to reduce their emissions by 20% by 2020 (based on 1990 levels), a figure that could climb to 30% depending on the outcome of the Copenhagen summit.

Sarkozy leads France's green diplomatic offensive

French President Nicolas Sarkozy has made the reduction of greenhouse gases one of his top diplomatic priorities and says he wants to make sure any accord that comes from the conference is going to have a real impact globally.

Sarkozy visited Manaus in the heart of the Amazon rainforest on Nov. 26 in order to persuade the countries of the Amazon to present an ambitious common proposal to Copenhagen.