World's Depopulation Problem

"Around the world, a demographic shift is underway, with people having fewer children. The resulting population decrease could -- more than hybrid cars or wind farms or policy shifts -- be our best hope for the salvation of the planet...But the real surprise may be that birthrates are falling even in developing nations. Throughout the developing world, the U.N. says, people are having fewer babies -- an average of fewer than three per woman -- and 20 developing countries have fertility levels below the 2.1 replacement level...So is this good news for those concerned about crowding and consumption?...Immigration and urbanization also create a sort of demographic microwave, leaving some areas ice cold and others blisteringly hot."