CompuServe Messages

John, Sure it is. But you -absolutely- can use refrigeration to cool the planet, and you don't have to toss hot rocks, either. What you have to do is radiate heat at night. And since radiative losses vary with the fourth power of T, it doesn't take too awful high a temperature to effectively radiate a big load of heat. Of course, it takes energy to accomplish this, so right now, less energy intensive ways are used, like evaporating water. Unfortunately, such evaporative cooling towers do NOT take the heat off-planet, and sooner or later we're going to have to go to a more active cooling cycle. But there's no thermodynamic violation here – there is no reason at all you can't use energy to pump more energy against a thermodynamic gradient. The only requisite is that the -overall- gain of entropy in the waste heat system is higher than the -overall- loss of energy in the system being cooled. So if you pump 100 megajoules of heat off planet, the amount of heat actually leaving has to be higher, say 150 megajoules. I suppose, in limit, you are raising the temperature of the cosmic background radiation, but I for one am not going to sweat it. — norm