Alicia T
2008-05-31 09:09:08 UTC
This is an essay written by Garrett Hardin, professor of human ecology. He is best known for his essay “Tragedy of the Commons.” The tragedy of the commons shows both an economic and political impact on renewable resources.
For many years, Angel Island in San Francisco Bay was plagued with too many deer. A few animals were transplanted there in the early 1900s lacked predators and rapidly increased to nearly 300 deer (far beyond the carrying capacity of the island). Scrawny, underfed animals tugged on the heartstrings of Californians, who carried extra food from the mainland to the island.
Such well meaning charity worsened the plight of the deer. Excess animals trampled the soil, stripped the bark off the small trees, and destroyed seedlings of all kinds. The net effect was to lower the island’s carrying capacity year by year, as the deer continued to multiply in a deteriorating habitat.
State game managers proposed that the excess deer be shot by skilled hunters. “How cruel!” some people protested. Then the managers proposed that coyotes be introduced onto the island. Though not large enough to kill adult deer, coyotes can kill fawns, thereby reducing the size of the herd. However, the Society for the Prevention to the Cruelty of Animals was adamantly opposed to this proposal.
In the end, it was agreed that some deer would be transported to other areas suitable for deer. A total of 203 animals were caught and trucked many miles away. From the fate of a sample of animals fitted with radio transmitters, it was estimated that 85% of the transported animals died within a year (most within a two months) from various causes: predation by coyotes, bobcats, and domestic dogs, shooting by poachers, and legal hunters, and being run over by cars.
The net cost (in 1982 dollars) for relocating each animal surviving a was $2,876. The state refused to continue financing the program, and no volunteers stepped forward to pay future bills.
Angel Island is a microcosm of the planet as a whole. Organisms reproduce exponentially, but environment does not increase at all. The moral of a simple ecological commandment: Thou shall not transgress the carrying capacity.
Now let’s examine the situation for humans. A competent physicist has placed the global human carrying capacity at 50 billion, about eight times the current world population of six billion. Before you give in to the temptation to urge women to have more babies, consider what Robert Mathus stated nearly 200 years ago: “There should be no more people in a country than could enjoy a glass and have a piece of beef for dinner.”
A diet of grain or bread and water us symbolic of minimal living standards; wine and beef are symbolic of higher living standards that that make greater demands on the environment. When land that could produce plants for direct human consumption is used to grow grapes for wine or corn for cattle, more energy is expended to feed the human population. Because carrying capacity is defined as the maximum number of animals (humans) an area can support, using part of the area to support cultural luxuries as wine and cattle reduces the carrying capacity. This reduced carrying is called the cultural carrying capacity, and it is always smaller than the simple carrying capacity.
Energy is a common coin in the realm of all competing demands on the environment. Energy can be saved by giving up a luxury can be used to produce more food staples and support more people. We could increase the simple carrying capacity of the earth by giving up any “luxuries”: street lighting, vacations, private cars, air conditioning and artistic performances of all sorts. But what we consider luxuries depend on our values as individuals and societies, and values are largely matters of choice. At one extreme, we could maximize the number of human beings at the lowest possible level of comfort, Or we could attempt to optimize the quality of life for a much smaller human population.
The carrying capacity of the earth is a scientific question. It may be possible to support 50 billion people at a bread-and-water level. The question, “What is the cultural carrying capacity?” requires that we debate questions of value, about which opinions differ.
At an even greater difficulty must be faced. So far, we have been treating carrying capacity as a global issue, as if there were some global sovereignty capable of enforcing a solution for all people. But there is no global sovereignty (“one world”), nor is there any prospect of one in the foreseeable future. Thus, we must ask how some 200 nations are to coexist in a finite global environment if different sovereignties adopt different ways of living.
Consider the protected redwood forest that produces neither food for humans nor lumber for houses. Because people must travel many kilometers to visit it, the forest is a net loss in the national energy budget. However, for those fortunate enough to wander through the cathedral-like aisles beneath an evergreen vault, a redwood forest does something precious to the human spirit. But then intrudes an appeal from a distant land, where millions are starving because their population has overshot the carrying capacity; we are asked to save lives by sending food. As long as we have surpluses, we may safely indulge in the pleasures of philanthropy. But after we have run out of our surpluses, then what?
A spokesperson for the needy from that land makes a proposal: “If you would only cut down your redwood forests, you could use the lumber to build houses and then grow potatoes on the land, shipping the food to us. Since we are all passengers together on Spaceship Earth, are you not duty bound to do so? Which is more precious, tree or human beings?”
The last question may sound ethically compelling, but let’s look at the consequences of assigning a preemptive and supreme value to human lives, At least 2 billion people in the world are poorer than the 34 million “legally poor” in America, and their numbers are increasing about one million per year. Unless this increase is halted, sharing food and energy on the basis of need would require the sacrifice of one amenity after another in rich countries. The ultimate result of sharing would be complete poverty everywhere on the earth to maintain the earth’s simple carrying capacity. Is that the best humanity can do?