Environment and Society. Paul Robbins

of overall affluence, this theory predicts that environmental impacts rise during development, only to fall after an economy matures

      Neo-Malthusians Present-day adherents to a position – established by Malthus in the nineteenth century – that population growth outstrips limited natural resources and presents the single greatest driver of environmental degradation and crisis

      While this formulation certainly makes the relationship between population and environmental degradation more complicated than Malthus did, it has been used by “neo-Malthusians,” those more recent adherents to a population-based way of thinking about environmental issues, to argue that population is the paramount factor in this equation. Paul Ehrlich (Ehrlich and Holdren 1974 , p. 1216) explains that population requires the most immediate attention “precisely because population is the most difficult and slowest to yield among the components of environmental deterioration.”

There are challenges to this assumption. Critics like Barry Commoner stress that technology has by far the greatest influence on environmental impact, far outweighing the total numbers of people, specifically citing the petrochemical-based economy, pesticides, fossil fuels, and a range of modern developments that increase individual impact enormously. As shown in Table 2.1, environmental impact varies enormously even in current economics. An alternative economy, by implication, would offset population growth (Commoner 1988).

Table 2.1 Who is overpopulated? Some comparisons of population, per capita gross domestic product, energy use, and other resource demands. Different places have widely divergent levels of population, affluence, and technology, with unclear implications for environmental impact

Country	Total population (millions)1	GDP ($ per capita)2	Energy use (kg of oil equivalent per capita)3	Percentage total forest cover change (including plantations), 1990–2016 4	Greenhouse gas emissions (tons of CO2 equivalent per capita)5
China	1428	10 098	2226	+33.6	8.0
USA	327	65 111	6916	+2.6	16.1
Bangladesh	161	1905	216	−4.5	0.6
Turkey	82	8957	1528	+22.8	5.1
UK	67	41 030	2978	+5.5	5.6
Kenya	51	1 997	492	−5.8	0.4
1: 2019, United Nations (2019) 2: 2019, International Monetary Fund (IMF 2021) 3: 2013, World Bank (2014) 4: 2016, World Bank (2018) 5: 2018, European Commission and the Netherlands Environmental Assessment Agency (2018))

      Others have argued that development radically lowers human impact, at a rate far greater than the growth of population. In what some analysts call an environmental Kuznets curve (named for economist Simon Kuznets), it is predicted that as development initially occurs, environmental impact increases, with per capita use of resources rising, pollution increasing, and damage to ecosystems like forests rising, and doing so at a rising rate. After a threshold, however, regulation, affluence, and economic transition begin to increase and impacts of humans fall dramatically. Proponents of this argument point out that in many parts of the developing world that have historically experienced high levels of deforestation, urbanization and affluence have left many rural areas abandoned, allowing a forest transition back to thick forest cover (Perz 2007, and see Chapter 12).

      Carrying Capacity and the Ecological Footprint

      On the other side of the equation, assuming agreement might be reached on how to measure impact per person, the degree to which each such impact is “too much” is also a matter of uncertainty. Just as IPAT and its variations predict future impacts of society on nature, the notion of carrying capacity is often invoked to signal the limits beyond which a local area can no longer absorb population. Carrying capacity is the number of people that could theoretically be sustained in one area (or the Earth) over an indeterminate amount of time, assuming a particular lifestyle (level of technology and consumption).

      Carrying Capacity The theoretical limit of population (animal, human, or otherwise) that a system can sustain

      Ecological Footprint The theoretical spatial extent of the earth’s surface required to sustain an individual, group, system, organization; an index of environmental impact

      Forest Transition Theory A model that predicts a period of deforestation in a region during development, when the forest is a resource or land is cleared for agriculture, followed by a return of forest when the economy changes and population outmigrates and/or becomes conservation-oriented

It has been estimated, for example, that if we calculate carrying capacity based on an assumption that all people lived like people do in the United States, the Earth could sustain only two billion people, or less than one-third of the world’s current population (Chambers et al. 2002). If this is taken seriously, we might have to ask how we can possibly decide who should be allowed to live at what standard of living. In other words, is it reasonable to insist that China not develop any further, so that levels of consumption in the United States and Europe can remain the same? Should people in North America demand that India limit its growth so that North Americans (in the United States and Canada) can maintain their own standard of living? For many people, these extremely problematic ethical questions have led to a desire to decrease their own impact on the environment – their ecological footprint.

The idea of an ecological footprint analysis is not so much to define the potential of an area to support a particular number of people at a particular standard (although it can do that), but rather to estimate the total