Either you believe man-made climate change is a nightmarish existential threat to civilization. Whichever it is, let’s at least agree mankind is dumping too much carbon into the atmosphere. Not convinced? Here are some numbers. Prior to the industrial revolution, the earth’s atmospheric carbon dioxide concentration was chilling somewhere around 280 parts per million. If we want to keep our planet habitable, respectable climatologists all agree, we need to keep that number below 350 parts per million, tops.