US President Barack Obama is "hopeful" his presence at the United Nations Climate Change Summit in Copenhagen can help nations reach an agreement, White House spokesman Robert Gibbs said Wednesday.

Gibbs also reiterated that any deal at the Copenhagen talks should be verifiable to make sure all parties are living up to their agreements on reducing carbon emissions.

However, according to the Bali Roadmap, it is developed countries whose targets of emissions reduction must be "measurable, reportable and verifiable." Meanwhile, developing countries' efforts toward sustainable development should be supported in a "measurable, reportable and verifiable" way in terms of technology, finance and capacity building.

Obama is scheduled to arrive in Copenhagen on the last day of the ongoing UN Climate Change Conference on Friday. The meeting aims to map out a comprehensive international arrangement for the fight against climate change over the period 2012-2020.

(Xinhua News Agency December 17, 2009)