ABSTRACT
The sentiment of the above quote is clear. If you have read the preceding chapters you have seen plenty of evidence that humans collectively are having significant impacts on the biosphere. Humans supply the world’s crops with more nitrogen than the traditional source, bacteria, [81, p. xiv], page 112. Humans have polluted nearly every niche of the biosphere on the planet, cf., Chapter 4. Humans are changing the climate of the entire planet and precipitating a great extinction more rapidly than any of the five great previous extinctions, cf., Chapter 1, [388]. Humans are significantly depleting the seas of life and even altering the chemistry of the world’s oceans, cf., Section 5.7. This list, which can be lengthened, might overwhelm with complexity. In the following I want to do simple, direct calculations, allowing little
room for disagreement, which give a picture of the earth not as some vast, imperturbable ball, but rather as a small world with a thin skin of water and air and a small dot of topsoil-upon which all of our lives depend. How Many People are on the Earth? When I first started working on
this book there were approximately 5.7 ∗ 109, or 5.7 billion people on earth (December, 1994). That amounts to about 285 million (metric) tons of human biomass, i.e., 2.85 ∗ 108 MT , assuming that the average person has 50 kg of mass. Norman Myers, [475, p. ix], notes that no other species on earth has a cumulative biomass larger than we humans, except perhaps ocean krill-
1David Brower was a charismatic conservationist living in Berkeley, California. He was the long time executive director of the Sierra Club, leading the fight to save the Grand Canyon and what is now Dinosaur National Monument from hydroelectric dams. He founded Friends of the Earth, and the Earth Island Institute as well as the League of Conservation Voters. Although he died on November 5, 2000 at his home at the age of 88, his prolific, heroic activist spirit lives on in many who work for the preservation and restoration of the natural world. David Brower voted absentee for Ralph Nader for U.S. president as, presumably, his last political act.
