Perhaps more than ever, the limitations of the environment on human population are evident. Population charted over time generally exhibits an exponential growth pattern. Combined with this growth, our demand for a higher standard of living has taken an increasingly greater toll on the environment. This interaction between human population and the environment is often thought of as a closed-system. For example, farmable land and current agricultural productivity set a limit on how much food the earth can provide. If the needs of the human population surpass this limit, then a disastrous collapse becomes probable. These models represent the humanities best attempt at forecasting our future relationship with the environment. They serve to highlight the dangerous ramifications of current behavior. For example, there is very little doubt about the human role in producing the greenhouse gases responsible for global warming. However, closed-system models are often interpreted in an extreme form as warning of an impending apocalypse. These extreme interpretations of closed-system models, or doomsday scenarios, tend to ignore the important role of technology and overemphasize historical patterns of human behavior.
Oil consumption is a topic of recent controversy and highlights the effect of natural limitations on human growth. One often-mentioned model is the Hubbert’s peak theory. Originally developed by Marion Hubbert in the 1950’s, the Hubbert’s peak theory is based on historical data on United States crude oil production. The model starts with three basic assumptions about the nature of crude oil production: production starts at zero, production then rises to a peak which can never be surpassed, production declines after the peak until it is no longer cost-effective to extract the resource (Deffeyes, 1). The resulting graph shows that once the peak has been reached, crude oil production will continuously decline.
The popular interpretation of this theory is a doomsday scenario in which insatiable global demand causes crude oil production to rapidly fall once Hubbert’s peak has been reached. As crude oil demand outstrips production capacity, the lack of energy causes a global recession and reduces living standards. Armageddon ensues as millions freeze to death from lack of heating oil and nations go to war in order to protect the few remaining petroleum reserves.
Another recent news item with dire implications is the effect of emissions of global temperatures. Rising CO2 levels produce a greenhouse effect, trapping heat in the atmosphere and increasing global temperatures. The doomsday scenario here involves rapidly rising sea levels engulfing coastal towns world-wide. Recent evidence, factoring the effect of Greenland’s glaciers, speculates the sea level to rise at more than one meter per century (Rincon, 1). This implies that New York City, standing only 1 meter above sea level, will be underwater in the next hundred years.
Though oil and global warming are recent issues, doomsday scenarios based upon extreme interpretations of closed-system models are centuries old. The works of Thomas Malthus, written just prior to the Industrial Revolution, can be considered the foundation of closed-system model and the forefather of modern doomsday scenarios. “…population, when unchecked, increased in a geometrical ratio, and subsistence for man in an arithmetical ratio.” (Malthus, Chapter 2) In such a system, population growth is unsustainable. Malthus offers some vivid imagery describing the effects of unsustainable population growth.
“Provisions no longer flow in for the support of the mother with a large family. The children are sickly from insufficient food. The rosy flush of health gives place to the pallid cheek and hollow eye of misery. Benevolence, yet lingering in a few bosoms, makes some faint expiring struggles, till at length self-love resumes his wonted empire and lords it triumphant over the world.” (Malthus, Chapter 10)
Malthus qualified his position by noting that man possesses the ability to effectively manipulate food supply but maintained that available food supply grows slower than population. Malthus developed his theories on the eve of the Industrial Revolution. At the time, high agricultural productivity and birth rates lead to large increases in the population of European countries. Malthus worried that this increase in the growth rate of the population was unsustainable.
Yet the predicted Malthusian crisis never occurred. The simple arithmetic growth rates of agricultural productivity, assumed by Malthus, failed to represent actual historical growth. Large increase in agricultural productivity arising from Smithian factors (expansion of the market, division and specialization of labor, and accumulation of capital stock) and technological advances defied the growth rates predicted by Malthus. To some extent, the increase in agricultural productivity arising from Smithian factors can forecasted using modern economic tools. However, even a revised and updated version of the Malthusian thesis fails to predict technological advances. The concept of using petrochemical fertilizers, the foundation of the Green Revolution, could not have been envisioned by Malthus. These technological advances are inherently unpredictable and defy accurate forecasting by closed-system models. However, to assume that humanity will invent itself out of every conceivable crisis is as naïve as to assume that humanity cannot invent itself out of the crisis. The important point is that the future contains a large degree of random, non-systemic, stochastic elements, principally being technological advances. Doomsday scenarios of closed-system models ignore this important element of uncertainty.
In addition, using a closed-system model to forecast doom assumes a static view of human behavior. Markets provide the system through which resource scarcity is conveyed through prices. Accordingly, as the impact of environmental constraints on natural resources increase prices, humans will be forced to reduce consumption levels. Efficient markets provide a clear mechanism through which consumption reflects resource scarcity. Thus for commodities with functioning markets, like oil, an image of human consumption sprinting towards the brick wall representing environmental limitations is exaggerated. As resources become scarcer, consumption levels will necessarily decrease.
However this implies that for environmental issues without markets, such as global warming, there is no mitigating mechanism. It is in these cases that closed-system models provide the most functionality. Since there is no market to reflect resource scarcity to the consumer, the only way to influence human consumption is through education and persuasion. The doomsday scenarios predicted by many closed-system models provide an effective means to convey the gravity of ecological limitations on human population. No one desires a closed-system doomsday model to accurately predict the future. These models were designed in order to point out the danger in a current consumption path.
The extent to which they are effective is in the model’s ability to produce changes in human behavior, not provide an accurate glimpse of the future. Inherently, closed-system models cannot include unknown technological innovations which shift the current paradigm. However, even in the absence of technological change, humans possess mechanisms to effectively react to environmental constraints. In some ways, closed-system models represent one of these mechanisms. At their best they provide awareness and education, not a reason to lose sleep at night.