I think the point about earth overheating is the one in that article that has the shortest timescale and therefore the most pertinent. As zapkitty points out, population stabilisation should help to stabilise energy consumption. But what if sufficiently abundant energy caused heat to be produced on earth faster than it could radiate off, shifting the overall temperature in and of itself? It’s not enough to say that greenhouse-gas-related climate change is mitigated; you can still overheat. We would need some way of either, on a massive scale, converting heat back into another form of energy, or some way of increasing the rate of heat transfer away from earth.
