Thus The Economist today. “Climate change poses economic and ethical challenges,” explains the newspaper. Now that climate change is starting to be taken seriously, some economists are saying that significant investment may be justified to fend it off. “There is a risk that climate change will happen faster or be more costly that we anticipate,” adds the newspaper, “possibly threatening humanity’s very existence.” But there is a question of how much people would be willing to pay today to avert the danger so many years later. This is the question of discounting. If we look much beyond a century, which adds up to four generations, the discount rate rises precipitously and costs quickly outweigh the benefits. The humanity’s very existence is valued at about zero in the long run. Alas, this is how the mental calculus works! In other words, significant investment may be justified only if benefits can be expected rather soon—say, two or three generations. But the mighty newspaper fails to mention what sort of investment, no matter how large, would be justified in this case. Cutting production so as to cut emissions of greenhouse gases? Geoengineering? Building protective structures to secure survival of large numbers of privileged people? Space colonization? This is where humanity would have no chance on deciding the best course of action. By comparison, choosing the appropriate discount rate would be a trifling.