Barack Obama

Experts hopeful Copenhagen deal could contain commitment to lower trade barriers for key clean technologies, kick-starting stalled Doha negotiations

Landmark ruling strengthens president's ability to deliver climate change deals in both Washington and Copenhagen

Boost for Copenhagen as reports emerge that the US Environmental Protection Agency will confirm this evening that it has the authority to impose new carbon rules

Flurry of good news dominates start of summit, as South Africa announces emissions target and Obama signals he will attend talks' conclusion

State news agency reports that long-awaited carbon target has been confirmed

And US will commit to greenhouse gas reduction target of 17 per cent below 2005 levels by 2020

Move comes only a week after China’s president Hu Jintao made a similar promise to reduce emissions

Senior White House official confirms Obama could still attend crucial climate summit

Leaders sign communiqué signalling they are prepared to table emission targets at Copenhagen Summit

Brown still hopes to salvage climate talks as US rules out binding targets