Carrying Capacity Malthus Updated
The state of subsequent ecological knowledge now permits restatement of the main theme from Malthus in the following terms Any species using any environment as its life-supporting base has the potential for increasing beyond the capacity of that environment to continue providing the needed support. Construing Liebig’s "law of the minimum" (Odum, 1989 129 -132) broadly, we can say a population is in deep trouble if an environment’s capacity to serve any one of these three functions has ceased to suffice, whether or not that environment continues to be sufficient for one or both of the other functions.
Malthus, we can reasonably assume, would fully accept such a reformulation if he were living today. A mind as insightful as his would surely recognize that after two further centuries of knowledge accumulation, how essential it is to construe "support" as involving all three uses of the environment.
It seems clear, moreover, that the consensus of contemporary ecological scientists would endorse the reformulation, apart from some lingering misunderstandings of the meaning of its fundamental term, carrying capacity.
Carrying capacity means, most succinctly, the maximum sustainable load. Sustainability is the essential ingredient of the concept. Overuse of an environment can impair its ability to sustain the user population. Extreme overuse can cause breakdown of ecosystem processes (Catton 1995). The maximum load that can be supported without beginning to cause system breakdown is the system’s carrying capacity for its users. In 1798 Malthus was not equipped by existing knowledge or vocabulary to make this as plain as can now be done, but this is what his essay was launching us toward eventually recognizing. We owe Malthus an immense debt for getting us started.
Two centuries further along in the development of technology, growth of human numbers, and accumulation of systematic knowledge about ecosystem processes, we have
no excuse for continuing to ignore or refusing to recognize the breakdown effects of overuse when they do occur. They are the indicators of human population’s having overshot carrying capacity —or, stated otherwise, they are symptoms that indicate our passage from a former era of carrying capacity surplus to a much different condition today,
an era of carrying capacity deficit.
If Malthus Was So Wrong, Why is the World in So Much Trouble?
Two centuries after Malthus,
it is dangerous to go on denying overpopulation and disregarding the ecological deficit.16 In the face of the ecological deficit’s increasingly discernible effects, no one should mistake the fundamental issues of our time. They are larger than simply the platitude about needing to put "jobs for people" ahead of protecting an "endangered species," or simply the call to favor "the economy" over "environmental special interests."
Such clichés are a form of denial. Denial is psychologically attractive, and on this matter it is socially favored, but this is hazardous to our future (Catton 1996). False prophets (e.g., Kahn et al. 1976; Simon and Kahn 1984; Wattenberg 1987; Simon 1994) come to us in the sheep’s clothing of technological optimism, encouraging the belief that inevitable progress will dependably overcome whatever problems we generate.
These commentators continue to insist that the carrying capacity concept has no relevance for either the population explosion or industrialization.
As they see it, the world cannot be considered overpopulated so long as most of its surface is not yet peopled as densely as, say, London or Tokyo. This overlooks the dependence of each thriving urban center on an Environment far more extensive than the territory within its own boundaries, an indispensable hinterland to serve its source and disposal needs.
Humanity’s future depends on unmasking these false prophets, and learning to know them by their fruits, by the consequences that would flow from stubbornly continuing to see the world in their Panglosian terms, by the ecosystem damage that would become ever more overwhelming (and irreversible) if we allow their discounting of Malthus to persuade us ecological foresight is merely a luxury.
…In science we can know causes only through the
effects that they produce. …Science studies heat through the variations in volume that changes in temperature cause in bodies, electricity through its physical and chemical effects, and force through movement.
There are in our time some effects and causes we urgently need to recognize that were unknown to people of past generations.15 The rising levels of greenhouse gases in Earth’s atmosphere, the widening holes in the stratospheric ozone layer,
the inexorable drawdown of many aquifers, the escalating depletion of mineral deposits and fossil fuel stocks, the deforestation of vast land areas, the loss of topsoil from farmlands, the spreading of deserts, the accelerating declines of species diversity all around the world —all of these must be seen as effects of populous industrialism (Ehrlich and Ehrlich 1990 58-59; Dietz and Rosa 1997), and should serve as signs we are seriously overusing our planet’s ecosystems.
This phrase
populous industrialism again makes my point, its not about how many ppl there are, there is no magic number of people, that once passed will spell our doom as the boy insists it must be expressed. Its about the way that population lives.
Overpopulation must be measured in the effects on the biosphere, not the number of humans currently alive
Or as stated in yet another way
Is it overpopulation or overconsumption we tend to deny? Given the expectations (and aspirations) of living people, this is a distinction without a difference. The sustainable number of Homo colossus (i.e. humans equipped with powerful "exosomatic organs" —modern industrial technology) on planet Earth must surely be much less than the sustainable number of non-industrialized Homo sapiens.
Some may argue that 6 billion would be a sustainable world population if all were willing to live at a pre-industrial level, but even if this were true, the prospect for global acceptance of an adequate degree of "voluntary simplicity" is dim. Given the presently occurring symptoms of ecosystem breakdown, it ought to be clear that if the "underdeveloped" Third World were to approach a First World level of living, then 6 billion would constitute overpopulation.
And the problem will not be eliminated just by pejoratively labeling such a statement "neo-Malthusian," as the cornucopian-minded and ecologically naive are inclined to do.