President Barack Obama will argue this week that the effects of climate change must be confronted now, intensifying his focus on the issue a month before new and contentious rules are due out that will regulate emissions from existing power plants. Tuesday’s release of a report called the national climate assessment will kick-start the administration’s push on an issue the president views as a key component of his legacy. The document, mandated by Congress and written by a federal advisory panel, will assess the impact global warming will have on specific regions of the country and sectors of the economy. The report and a series of events in the next few days offer Mr. Obama an opportunity to reassure his liberal allies, who have long urged a more aggressive approach to climate change. Mr. Obama has told environmental leaders, including some top Democratic donors, his administration is ready to […]