The decision this week by European leaders to fast-track ratification of the Paris Agreement on Climate Change is historic. It is now certain that less than one year will have passed from the beginning of the COP21 climate negotiations in December 2015 to the moment when the Paris Agreement will come into force. These weeks and months are when the nations of the world stared over the precipice of catastrophic climate change and chose to act. By standards of international diplomacy, the ratification of the Paris Agreement has been remarkably swift. Leaders of the many nations who have ratified the deal deserve our praise and gratitude. From the biggest emitters, China, the United States and the European Union, to the smallest Island nations that are most at risk from the effects of climate change, each has recognized the scale of the threat we face and acted with commendable speed.