As you’ve likely heard, the ocean’s health is in trouble. You’re probably aware of overfishing and the harmful practices of fisheries driving a third of the planet’s fish stocks toward extinction, and you surely know about the unconscionable amount of pollution, in particular plastic, that we dump in the ocean. But that’s not the worst of it. The ocean is steadily warming; its oxygen levels are falling; and it is becoming more acidic, making conditions for life below the waves ever harder. Planet- warming greenhouse gases are the common enemy in that trio of changes. And by now we all know who has been creating those gases.