Miami will likely be underwater before the Senate can muster enough votes to meaningfully confront climate change. And probably Tampa and Charleston, too-two other cities that last week’s National Climate Assessment placed at maximum risk from rising sea levels.

Even as studies proliferate on the dangers of a changing climate, the issue’s underlying politics virtually ensure that Congress will remain paralyzed over it indefinitely. That means the U.S. response for the foreseeable future is likely to come through executive-branch actions, such as the regulations on carbon emissions from power plants that the Environmental Protection Agency is due to propose next month. And that means climate change will likely spike as a point of conflict in the 2016 presidential race.

President Obama, from his first days in office, made it clear to intimates that he believed a legislative solution to climate change would provide a more stable, broadly accepted response than executive action. But his experience has highlighted the structural forces that make a legislative agreement so unlikely, especially in the Senate.

Reaching agreement on any issue has become increasingly difficult in a Congress deluged by partisan polarization and money from interest groups. But climate change faces two other headwinds that make the path […]