The American Academy of Arts and Sciences was founded in 1780, during the American Revolution, to provide guidance to a young nation. Throughout its 241-year history, the Academy’s leadership has seldom issued organizational statements, preferring to have its projects, studies, publications, and convenings present the best available thinking about the topics in question. However, when a situation arises – like climate change – that profoundly threatens the world, a call to action from the Academy’s Board of Directors is appropriate.