New York Times: Citing progress on many issues, the White House said Friday that President Obama had shifted the date he would appear at the United Nations climate change conference in Copenhagen to Dec. 18, the last scheduled day. In a written statement, it said the president believed that he could have a more decisive impact by appearing at the end of the 12-day conference, when as many as 100 other heads of state are scheduled to show up, rather than next Wednesday as originally …