"Another measure of our wholesale plunder of the ecosystem is provided by estimating the net primary production (NPP) of the planet, defined as the sum of all photosynthetic production minus the energy required to maintain and support those plants. The annual figure arrived at is in the area of 225 billion metric tons of wood, grass, fiber, and food. Of this total, 60 percent is produced on land and 40 percent in the oceans. An oft-quoted study* suggests that our human economy currently utilizes, consumes, converts, burns or clear cuts annually 40 percent of the total NPP on land. In short, one species - our own - out of 5 to 30 million species (no one is sure how many there are) is directly and indirectly claiming 40 percent of the earth's production for itself. This fact alone should give businesspeople pause when they think their taking of water, forests, land, or minerals has minimal impact. If, as predicted, our population doubles sometime in the next forty or fifty years, we will usurp 80 percent of the primary production of the planet, assuming no increase in the standard of living. If our standard of living doubles in the next forty years - the accepted projection - we will quadruple our impact, a physical impossibility.
In fact, we may have already reached the diminishing point. We are already seeing many dangerous signs of this usurpation of planetary production, foremost of which is the loss of other forms of life - extinctions. Before we reach 60 or 70 percent utilization of the NPP, we will witness an ecological crash. Hundreds of thousands of species will vanish, because they will not be able to compete with us for food. These newly depleted ecosystems will be reduced to soil substrates into which we will have to force increasing amount of chemicals to grow decreasing amounts of food."
* P. Vitousek, P. Ehrlich, A. Erhlich, and P. Matson, "Human Appropriation of the Products of Photosynthesis", Bioscience, June 1986, 36-6.
Paul Hawken, The Ecology of Commerce. A Declaration of Sustainability.
(Chapter "The death of birth").