We Can't Have Our Earth And Eat It Too!

If every fertile woman in the world was limited to one child...and it somehow began tomorrow, our current 6.5 billion human population would drop by 1 billion by the middle of this century. (If we continue as projected, it will reach 9 billion.) At that point, keeping to one-child-per-human-mother, life on Earth for all species would change dramatically. Because of natural attrition, today’s bloated human population bubble would not be reinflated at anything near the former pace. By 2075, we would have reduced our presence by almost half, down to 3.43 billion, and our impact by much more, because so much of what we do is magnified by chain reactions we set off through the ecosystem. By 2100, less that a century from now, we would be at 1.6 billion: back to levels last seen in the 19th century, just before quantum advances in energy, medicine, and food production doubled our numbers and then doubled us again. At the time, those discoveries seemed like miracles. Today, like too much of any good thing, we indulge in more only at our peril. At such far-more-manageable numbers, however, we would have the benefit of all our progress plus the wisdom to keep our presence under control. That wisdom would come partly from losses and extinctions too late to reverse, but also from the growing joy of watching the world daily become more wonderful. The evidence wouldn’t hide in statistics. It would be outside every human’s window, where refreshed air would fill each season with more birdsong. ~Alan Weisman, "The World Without Us"