Although environmental degradation at the geographically localised level has occurred from time to time since even before recorded history, their global reach is a more recent phenomenon. Ecologists’ findings suggest that a near-50 percent increase in world population, allied to a doubling of gross world product per head, by year 2040 or so, would create substantial additional "stresses" in both local and global ecosystems.For example, global "demand" for food could easily double over the period
1990-2030, with two-and-a-half to three-fold increases in the poorest countries. Of particular concern are Asia and Africa where, over the next fifty years, plant-derived food-energy requirements are expected to increase by a factor of 2.3 and 5, respectively, with a more-than-sevenfold increase expected in some countries.