Now we know what we’ve done. Or we should. The fuel-burning binge (and the beef-eating binge, and the forest-clearing binge) we’ve been on for the past 150 years, and especially the last 60, and increasingly and accelerantly, has brought into view the most dangerous threat in the brief history of our civilization. It’s become possible to glimpse the disappearance of so many things, not just glaciers and species but ideas and institutions too. Things may never be so easy or orderly again. Our way of life that used to seem so durable takes on a sad, valedictory aspect, the way life does for any 19th-century protagonist on his way to a duel that began as a petty misunderstanding. The sunrise looks like fire, the flowers bloom, the morning air dances against his cheeks. It’s so incongruous, so unfair! He’s healthy, he’s young, he’s alive—but he’s passing from the world. And so are we, healthy and alive—but our world is passing from us.