“By 2005, Moore was referring to the gyrating Pacific dump as 10 million square miles—nearly the size of Africa. It wasn’t the only one: the planet has six other major tropical oceanic gyres, all of them swirling with ugly debris. It was as if plastic exploded upon the world from a tiny seed after World War II and, like the Big Bang, was still expanding. Even if all production suddenly ceased, an astounding amount of the astoundingly durable stuff was already out there. Plastic debris, Moore believed, was now the most common surface feature of the world’s oceans. How long would it last? Were there any benign, less-immortal substitutes that civilization could convert to, lest the world be”