In September, just a few days after French President Emmanuel Macron’s environment minister resigned to protest the watering down of his policies, actress Juliette Binoche tapped 200 like-minded artists to sign a manifesto calling for “firm and immediate” action on climate change. “We are living through a planetary cataclysm,” said Ms. Binoche, in a missive published in Le Monde alongside the likes of director Pedro Almodovar, actor Jude Law and writer Michael Ondaatje. “We thus consider that any political action that does not make fighting this cataclysm its concrete, declared and assumed priority will no longer be credible. We consider...