The human population continues to grow explosively, although the rate at which it is increasing has been slowed in the past few decades. Nevertheless, the last billion human beings have been added during the past 12 years! Population pressures, particularly acute in tropical areas, force the acquisition of ever more agricultural and habitable land, and, as suitable lowland fertile areas have already been brought under the plow, more and more marginal and fragile lands with poor soil, hills and mountains are being cultivated. Also, as human numbers increase, mankind appropriates more and more of the total solar energy and primary productivity of the earth. At present humans use almost 40% of the solar energy captured in organic matter. Many, if not all, of the following causes of rainforest destruction are closely linked to the exponential growth in human population during this century. The disappearance of rainforests and biodiversity is proportional to the rate of expansion of the human population.