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Unformatted text preview: 15 Natural Constraints and Time Had we but world enough, and time, — ANDREW MARVEL, "To His Coy Mistress", 1681 Food, Water, Energy, land, soil, space, diseases, waste disposal, nonfuel minerals, forests, biological diversity, biologically accessible nitrogen, phosphorus, climatic change—all have been proposed as potential natural constraints that do or could limit the Earth's human population. These factors are closely interconnected, as the case study of water illustrated. For most goods and services (like food, energy, aluminum, nitrogen or natural removal of wastes), one could ask the same six questions just considered for water: How much is available? (This question divides naturally into two parts: What are the physical, chemical or biological supplies? What are the economic, social and cultural limitations on using the supplies?) How much is required? (This question also divides: How much for subsistence? How much for a wealthy style of life?) How many people can the available supply support (at different levels of well-being)? How does each good or service connect with others? Does a good or service limit human population through its effects on birth, death and migration? How could radical developments affect the good or service? The same questions that are asked of goods could be asked of bads, like disease, earthquakes and the unwanted effluents of industrial or agricultural production. Each potential natural constraint has its scholarly and popular enthusiasts. Each has inspired a vast number of technical reports and popular books. For each potential constraint that someone claims is crucial, someone else denies that it matters much at all. 1-329- HOW CAN NATURAL CONSTRAINTS BE ORGANIZED? A major problem in thinking about natural constraints is how to organize them. Many taxonomies of natural constraints have been proposed. Here is a sample of taxonomies. None is perfectly satisfactory. N. H. Biegman, a Dutch government official in charge of international cooperation, proposed in 1992 a three-part classification of natural functions: the supply of inputs; environmental regulation, including the removal of wastes; and genetic memory. Each function implies a natural constraint over some time period that has to be determined. According to Biegman, people cannot draw more inputs than nature can provide "sustainably"; people cannot dump more wastes or otherwise disrupt the environment more than the environment can tolerate "sustainably"; and people cannot deplete the genetic memory of nature faster than biological diversity is renewed "sustainably." By the word "sustainably, " Biegman meant that "Consecutive generations must protect the environment so that nature can continue to fulfill its functions for us." 2 Biegman's taxonomy falls to distinguish dangerously rapid from negligibly slow depletion or degradation of natural functions; he does not specify over what time scale the natural functions operate as global constraints. natural functions operate as global constraints....
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- Spring '11
- Infectious Disease, World population