The largest climate summit in history opens today here in Copenhagen. Thousands of delegates and more than 100 world leaders are expected over the next two weeks as negotiations are held to replace the 1997 Kyoto Protocol. Achim Steiner of the UN Environment Programme said he expects the conference will result in a binding agreement.

Achim Steiner: “For those who claim that in Copenhagen a deal is impossible, they are simply wrong. You have a world summit taking place now with over 100 heads of government and heads of state coming. This is not a negotiating session; this is a meeting to complete a negotiation process that has lasted for over two years and is meant to end in a deal.”

The White House has bolstered hopes of a climate deal with the announcement President Obama will attend the talks on the summit’s last day. Obama had initially planned to visit Copenhagen this Wednesday before accepting the Nobel Peace Prize in Oslo. But Obama will now be present as dozens of heads of state try to reach an agreement. The top UN official for the Copenhagen conference, Yvo de Boer, said he hopes Obama will hear the demands of developing nations.

Yvo de Boer: “I’m happy that he’s coming towards the end of the conference, together with other heads of state and government. I think it’s important for him to interact with them. I think it’s especially important for him to hear the concerns of small island developing nations, the countries that are most vulnerable to the impacts of climate change.”

Poorer nations have widely criticized the US for its stated pledge of reducing greenhouse emissions by around 17 percent of 2005 levels, which amounts to around four percent of the world standard of 1990 levels. The world’s top scientific body on global warming, the UN Intergovernmental Panel on Climate Change, has called on developed countries to cut emissions by between 25 to 40 percent of 1990 levels.