Human population is in the news. New forecast suggests that there will be eleven-billion humans by the end of the century. This is up by at least a billion by comparison with earlier forecasts. Together with the news, there is much debate about the connection between population and sustainability. Many commentators warn that too many humans cannot be sustainable. And so on, and so forth. Not one single article I have come across mentions climate change and the possibility that the human population will be decimated because of it. The same holds for World War III. Throughout, the assumption is that the rest of this century will be just as trouble-free as the period following World War II. This sort of device is perfectly plausible in any scientific exercise, such as a population forecast, but it is quite questionable in much of the debate that comes in its wake. Most important, the assumption is not even mentioned as such, let alone debated. It is treated as something perfectly plausible. Nay, indisputable. Given all the givens, though, the ridiculous assumption is nothing if not perilous.