There’s much more to do, but we should be encouraged by the progress we have madeToday marks the 10th anniversary of the Paris climate treaty, one of the landmark days in climate-action history. Attending the conference as a journalist, I watched and listened and wondered whether 194 countries could ever agree on anything at all, and the night before they did, people who I thought were more sophisticated than me assured me they couldn’t. Then they did. There are a lot of ways to tell the story of what it means and where we are now, but any version of it needs respect for the complexities, because there are a lot of latitudes between the poles of total victory and total defeat.I had been dreading the treaty anniversary as an occasion to note that we have not done nearly enough, but in July I thought we might be able celebrate it. Because, on 23 July, the international court of justice handed down an epochal ruling that gives that treaty enforceable consequences it never had before. I...