It’s official: Barack Obama will attend the Copenhagen climate conference on December 18, the final day of scheduled negotiations. Originally slated only for a brief stopover at the start of the conference, en route to accepting his Nobel Peace Prize in Oslo, Obama’s change in schedule is making enviros hopeful. Politico called it “a strong signal that U.S. negotiators believe the negotiations could result in a political agreement to curb greenhouse gases worldwide and a framework for signing a legally binding treaty in 2010.”

Obama’s original plans had been criticized by other world leaders. In a not-so-subtle critique of the president’s itinerary, France’s Nicolas Sarkozy had bemoaned the fact that “the decisive moment is December 17 and 18. If some come at the beginning and others at the end, when will we be able to take decisions?”

National Security Advisor Jim Jones set off speculation about the president's schedule earlier today by hinting at the possibility of a switch. White House Press Secretary Robert Gibbs officially confirmed it in a statement this afternoon. Obama made the decision after talks this week with Australian Prime Minister Kevin Rudd, German Chancellor Angela Merkel, British Prime Minister Gordon Brown, and Sarkozy. The discussions among these top leaders seemed to indicate what Gibbs described as an “emerging consensus” on initial funding in the range of $10 billion a year by 2012 for developing countries, one of the crucial moving pieces in any climate deal.