The Paris Agreement has achieved one of two key necessary conditions for ultimate success - a broad base of participation among the countries of the world. But another key necessary condition has yet to be achieved - adequate collective ambition of the individual nationally determined...

We describe three essential elements of an effective post-2012 international global climate policy architecture: a means to ensure that key industrialized and developing nations are involved in differentiated but meaningful ways; an emphasis on an extended time path of targets; and inclusion of...