Cheikh tidiane Ndour Cheikh Anta Diop University   cheikht.ndour@ucad.edu.sn cheikht.ndour@ucad.edu.sn cheikht.ndour@ucad.edu.sn Dakar,   cheikht.ndour@ucad.edu.sn             JEL Areas: E : Macroeconomics and Monetary Economics Q5 : Environmental Economics: General