The world’s two largest greenhouse gas emitters have ratified the Paris Agreement on climate change, bringing the landmark deal significantly closer to entering into force. The news of the US-China effort comes ahead of a series of meetings by different UN bodies over the coming months, all aiming to bring various climate-related processes across the finish line. The ratification announcement was made jointly by US President Barack Obama and Chinese President Xi Jinping, and came just ahead of this year’s G-20 summit, which was hosted by China. The two leaders also made a series of other climate-related announcements relating to international civil aviation and the potential phase-out of hydrofluorocarbons. “This is the single-best chance that we have to deal with a problem that could end up transforming this planet in a way that makes it very difficult for us to deal with all the other challenges that we may face,” said Obama regarding the Paris accord. The UNFCCC has 197 parties, with the vast majority of these having already signed the deal. At press time, 26 of the 180 signatories to the Paris Agreement have submitted their instruments of ratification, including the US and China. According to the UNFCCC, these...