Barack Obama will renew his commitment to green America's economy and join international action on global warming in a speech to the United Nations climate change summit on Tuesday. The appearance is a chance to offer much needed assurances to nearly 100 world leaders that the president can deliver on his promise for early action on climate change – now that the issue has taken second place to health care in the Senate. The delay has added to uncertainty that the Senate will move forward on a bill to reduce greenhouse gas emissions before the crucial climate change summit at...