Roughly 100 world leaders are traveling to Baku, Azerbaijan, for the U.N. Climate Change Conference — even as scores are skipping the annual talks, known this year as COP29. In a Tuesday address before world leaders speak at the summit, U.N. Secretary General António Guterres described the previous year as a “master class in climate destruction,” adding, “The sound you hear is the ticking clock.” He also expressed optimism about the transition to clean energy, saying that “no group, no business, and no government” can stop it. Swedish activist Greta Thunberg chose to skip the conference: Speaking Monday at a...