 A second option is to think that future people have rights and hence that, on the view under consideration, they too have an equal right to emit greenhouse gases. If, however, one thinks that all current and future persons are entitled to equal per capita emissions then we face two severe problems. (i) It will be exceptionally difficult, if not impossible, to calculate how much everyone is entitled to. Furthermore, (ii), given the number of future and present people included the equal per capita share would surely be close to zero.