Mr. Obama, who had previously not committed to making an appearance at the summit, will deliver a speech on Dec. 9 en route to Oslo, Norway, where he will accept the Nobel Peace Prize on Dec. 10.
Mr. Obama had been under considerable pressure from other world leaders and environmental advocates to make the trip as a statement of American commitment to the climate change negotiations. The talks, involving more than 190 nations, are expected to produce a wide-ranging interim political declaration but stop short of proposing a binding international treaty.
Delegates are expected to commit to completing the treaty next year.
Mr. Obama has said recently that he would attend the session if his presence could help lead to a successful outcome. Mr. Obama will tell the delegates to the climate conference that the United States intends to reduce its greenhouse gas emissions “in the range of 17 percent below 2005 levels,” according to a White House official.
The administration has resisted until now delivering a firm pledge on emissions reductions because Congress has not yet acted on global warming legislation. But officials said earlier this week that Mr. Obama was now prepared to offer a tentative figure based on the work completed in Congress so far.
In June, the House passed a bill calling for greenhouse gas reductions of 17 percent below 2005 levels. Last month, a Senate committee passed a measure calling for a 20 percent cut, but that is expected to be weakened as the legislation moves through other Senate committees and onto the floor, perhaps next spring.