Beleaguered by mutual recrimination between rich and poor countries, squeezed by the zero-sum arithmetic of a shrinking global carbon budget, and overtaken by shifts in economic and hence bargaining power between these countries, international cooperation on climate change has floundered. Given these three factors - which Arvind Subramanian and Aaditya Mattoo call the "narrative," "adding up," and "new world" problems - the wonder is not the current...