US President Barack Obama's winning of the Nobel Peace prize should encourage him to commit to an international treaty on global warming, the UN climate chief said Friday. As two weeks of UN climate talks concluded in Bangkok, there were fears of time running out for 192 countries to reach an agreement ahead of a December showdown in Copenhagen, the deadline for a deal to tackle global warming. The UN's top climate official, Yvo De Boer, said he hoped Obama's win would be 'an encouragement for him to bring a strong commitment to Copenhagen'. The looming question of how Washington will fit into any new agreement has dominated the talks in the Thai capital and there are now just six days of negotiations, in November, before the critical Denmark gathering. Hopes for a leading US role in the world's climate change efforts have been dampened by indications that its Congress will not pass major legislation on the issue by the end of the year. 