The world's second largest producer of CO2 has long been a barrier to binding international emissions agreements. Barack Obama has a more co-operative, science-driven approach than his predecessor but must contend with domestic hostility to any restrictions on manufacturing. Likely to agree to cut emissions to 17 per cent below 2005 levels by 2020, but press for developing nations to accept more responsibility.
Passed the US to become the world's largest carbon emitter in 2006, and has shown a similar unwillingness to sign up to any environmental agreements that may limit its economic growth. Demanding that richer nations stick to demanding CO2 reduction targets to allow developing countries to increase emissions as they go through industrialisation. Its own pledge to cut carbon emissions per unit of GDP by 40 per cent by 2020 – giving it plenty of room to pollute more as its economy grows – has not impressed the EU. China also wants the West to fund low carbon technology and climate adaptation projects in poorer countries.
Will not commit to binding emissions targets, claiming that rich countries have sole responsibility to fix a problem they have created. Signed a declaration with China, South Africa and Brazil in advance of the summit pledging a joint walkout if the developing world attempts to violate their "non-negotiable" opposition to enforced cuts. But despite the rhetoric, India's vulnerability to rising sea levels means it is not deaf to the threat of global warming - it has agreed to limit its own emission growth.
New prime minister Yukio Hatoyama has promised to cut emissions to 25 per cent below 1990 levels by 2020, if other countries pledge similar reduction. The commitment is much bolder than any made by the previous administration, and reflects Japan's aim of becoming a hub for the development of green technology. Also wants developing countries make more of an effort to reduce emissions.
Has pledge to cut emissions by 20 per cent from 1990 levels by 2020, and adopt even tougher targets if China and the US sign up. An eye-catching goal of reducing emissions by 95 per cent by 2050 allows the EU to pose as a leader in the fight against climate change, although developing nations say its post-industrial economies could survive more swingeing cuts. The EU has softened its criticisms of American intransigence in the hope of sweet-talking the US into a binding deal.
The underwater cabinet meeting held by the Maldives government in October thrust the tiny Pacific island state to the forefront of the debate about global warming. IPCC predictions suggest that rising sea levels will make the country virtually uninhabitable by 2100. President Mohamed Nasheed has put himself forward as the world's climate change conscience, handing his country (pop. 309,000) an extraordinary symbolic importance at Copenhagen.