A group made up of environmental organizations and labor unions is asking the president to lead a national conversation on climate change.

In a statement to President Barack Obama, the BlueGreen Alliance, whose members include the Sheet Metal Workers union, called on the White House to limit carbon emissions through the Environmental Protection Agency. It also asked for increased infrastructure spending and said the debate over global warming is long over.

“The dramatic impact of Hurricane Sandy can and should be the end point of our confusion on the central questions concerning climate change: It is real, it is accelerated by human actions, and if we fail to preempt its frightening costs, we will imperil our economic future,” the letter said. “For too long, our environmental imperatives were falsely seen as standing in conflict with the economic aspirations of all Americans. It is critical that the administration and the next Congress solve these problems in harmony.”

 Along with Joseph Nigro, president of International Association of Sheet Metal, Air, Rail and Transportation Workers, the letter was also signed by United Auto Workers union President Bob King and William Hite, United Association of Journeymen and Apprentices of the Plumbing and Pipe Fitting Industry, and nine other representatives of groups such as the Sierra Club and the National Wildlife Federation.