Environment and Society. Paul Robbins

Earth’s resources provide the most definitive and powerful limit for human growth and expansion.

Exponential Growth A condition of growth where the rate is mathematically proportional to the current value, leading to continued, non-linear increase of the quantity; in population, this refers to a state of increasingly accelerated and compounded growth, with ecological implications for scarcity

      In more careful phrasing, Malthus was clear to describe the mathematical underpinnings of this relationship, stressing that population growth is effectively “geometric” (“exponential” in today’s terms), since the multiple offspring of a single mating pair of animals or people are each capable of producing multiple offspring themselves. Assuming six children from every mating couple (a family size typical in Malthus’ time), for example, means a growth of 6 in the first generation, 18 in the second generation, 54 in the third, and so on. That growth, when graphed, takes the form of a curve, much steeper than a straight line, moving toward an asymptote, that is, a steep increase in a few generations and a large number of individuals, increasing every generation.

      On the other hand, Malthus argued, the food base for this growing population over time is essentially fixed or, perhaps, amenable to slight alteration through “arithmetic” (“linear” in today’s terms) expansion. Food supplies can grow by putting more land under the plow, for example, but not nearly at the rate that population expands. Over time “geometric” growth always outpaces “arithmetic” growth, with obvious implications.

      These implications sit at the center of Malthus’ key written work, An Essay on the Principle of Population (Malthus 1992), which he first published in 1798. Here, Malthus suggested, wars, famine, destitution, and disease are natural limits to growth and act to keep population in check. Second, he maintained that policies promoting the welfare of the poor are counterproductive, because they only encourage unnecessary reproduction and resource waste. Third, he argued that the key to averting periodic and inevitable resource crisis is a moral code of self-restraint.

In terms of natural limits Malthus suggested that famine, starvation, and death were predictable. He insisted, moreover, that the iron laws of scarcity meant that periodic crises and population collapses were practically inevitable, even in a world where some expansion in resources occurred over time. These hypothetical cyclical population-driven crises are sketched in Figure 2.1, which shows a model of the Malthusian dynamic of population versus natural resources.

Figure 2.1 Hypothesized demographic trends in a Malthusian conception. Limits of the environment, though they are amenable to steady increases resulting from growths in resource production, control human population trends with periods of high growth followed by periodic calamities and corrections that bring population back in line with the environment.

      Malthus freely admitted that the poorest people were the most vulnerable parts of the population. He insisted, however, that efforts to sustain, protect, or subsidize the conditions of the poor were largely pointless, insofar as they bolstered or supported population growth. Malthus, though, was even harsher in his assessment of the poor. He suggested that the poor are reliant on handouts, that they are bad managers of time and money, and that they are given to irrational procreation.

      Rather than provide support for people, Malthus insisted that the best remedy to these crises is the expansion of moral restraint. Specifically he intended the moral restraint of women, whom he held responsible for the maintenance of virtue and, by implication, for population run amuck. He especially focused his criticism on “less civilized” peoples (seen as those from southern Europe at that time) whom he viewed as insufficiently capable of self-control, and so inevitably given to poverty.

      It can scarcely be doubted that, in modern Europe, a much larger proportion of women pass a considerable part of their lives in the exercise of virtue than in past times and among uncivilized nations. (Malthus 1992, Book II, Chapter XIII, pp. 43–44)

      In some of the southern countries where every impulse may be almost immediately indulged, the passion sinks into mere animal desire, is soon weakened and extinguished by excess. (Malthus 1992, Book IV, Chapter I, p. 212)

      The social and political biases of the Essay on the Principle of Population and the context in which it was written are clear. Malthus developed an explanation for poverty that absolved economic systems, political structures, or the actions of the wealthy or elite from fault. His specific moral vision of women, perhaps even by the standards of his own time, reflects a profoundly biased view of the relationship between women and men.

      Actual Population Growth

      Examination of some recent trends also reveals that after two hundred years of demographic history, a few of Malthus’ key claims are indeed sustained. To be sure, the exponential nature of human population growth in the past few centuries is quite clear.

That growth is roughly shown in Figure 2.2. Where the world at the time of the Roman Empire two thousand years ago contained only 300 million people, today it holds more than 7 billion, more than a 20-fold increase, most of which occurred in only the last century.

Figure 2.2 World population since 1750. Rapid increases in recent decades reflect exponential growth. Source: Source: Modified from Demeny, P. (1990). Population. In B.L. Turner, W.C. Clark, R. Kates, et al. (eds.) The Earth as Transformed by Human Action. Cambridge: Cambridge University Press.

      So even while there are numerous profound limits and problems in this formulation (and more as we will see below), the arguments of Malthus and his present-day followers certainly raise questions about the relationship between society and environment and the nature of resource scarcity, its possible inevitability, and our capacity to overcome it.

      Population, Development, and Environment Impact

      The questions raised by Malthus have been taken up by other scholars interested in relationships between population, economic development, and environmental impacts. One approach, pioneered by Paul Ehrlich and John Holdren (1974), seeks to measure the impact of human beings on the environment, taking seriously not only raw numbers of people but also their overall rate and type of consumption. They proposed that every additional person added an impact on the Earth, though the exact rate of that impact was influenced by other factors including the average affluence of a population (a person in Bangladesh uses far less water and energy than one in the United States, for example) and the availability of technology that might lessen human impact (a population using solar power rather than coal power may have far lower carbon emissions, for example, depending on how solar panels are produced and how much energy their owners use). For this relationship they developed a shorthand equation (IPAT) to determine the level of environmental impact (I) as a product of population (P), affluence (A), and technology (T):

      I = P*A*T

      Here, environmental impacts are understood broadly as the deterioration of the resource base, the decline of ecosystems, the production of waste, and so on, while population is the number of people in a specific group (usually a country). Affluence, a measure that was not considered in any way by Malthus, is alternatively measured as either 1) the level of consumption of the population or 2) the per capita gross domestic product. In other words, one considers how many goods per capita (per person) are consumed in that country or area or the total production in the country, divided by the population. Technology, also not considered by Malthus, is the set of methods available to that population to produce the goods that are needed and consumed.

      Kuznets Curve (Environmental) Based in the theory that income inequality will increase during economic development and