Dear colleagues, in 1883, Sidgwick wrote: ? So, again, if it is economically advantageous to a nation to keep up forests, on account of their beneficial effects in moderating and equalising rainfall, the advantage is one which private enterprise has no tendency to provide ; since no one could appropriate and sell improvements to climate ? Henry Sidgwick, The Principles of Political Economy p. 406, 3d. ed 1901, 1st Ed 1883 I was wondering what the main reason would be why Sidgwick did not see that improvements to climate could actually be sold (through a tradable quotas scheme). Any suggestions? Many thanks in advance, Yours sincerely, Axel Gosseries