Prime minister-designate Justin Trudeau will face one of his first major international tests at next month’s United Nations’ meeting on climate change in Paris. In all, 25,000 delegates -- including Canada’s premiers whom Trudeau plans to bring along -- from 196 countries will make yet another attempt to draft a binding global agreement to fight man-made global warming. But the same fundamental disagreements which scuttled a similar deal in Copenhagen in 2009 and, prior to that, produced the failed 1997 Kyoto accord, still exist. Developed nations, led by the U.S., want the developing world to agree to binding targets on...