President Obama will attend the international climate negotiations in Copenhagen next month, according to a senior administration official, a sign of the president’s increasing confidence that the talks will yield a meaningful agreement to reduce greenhouse gas emissions.

The White House will also announce today that the United States will commit, in the talks, to reduce its emissions of the heat-trapping gases scientists blame for global warming “in the range of” 17 percent below 2005 levels by 2020, the official said. That’s the target set out in the climate bill the House passed in June.