Thus the Financial Times today. “Shrinking population and ‘scrap and build’ culture lead to eight-million empty homes,” elaborates the newspaper. Some of these houses are derelict or overgrown with plants, and others are in fine condition. Given many earthquakes, Japanese houses are not meant to last long, whence the notion of scrap and build. The shrinking population means that many are abandoned for good. The Japanese government estimates that some twenty percent of residential areas will become ghost towns by the middle of the century. Meanwhile, new houses and apartments continue to be built, the article points out. The new buildings are much more earthquake resistant, which makes them attractive to younger buyers. Among other things, this is a generational change. The old houses are dying together with their owners. At any rate, Japan now provides a model of how rapid population decline may look in the future. There will be several such models across the world, but derelict buildings will quickly become overgrown with plants almost everywhere. Ghost towns will crumble and become overgrown forests. Those who remain behind will quickly learn to mine these strange places for all sorts of useful things. Soon enough, trade will develop in such things. Ah, what a boon for science fiction…