Aggregate consumption (a function of population, per capita consumption

Beyond improved efficiencies and enhanced production, all pathways to reducing biodiversity loss entail reducing or reversing the growth of aggregate consumption, as a function of

population size and per-capita consumption and waste. Per-capita consumption tends to rise as income rises, putting further pressure on biodiversity. Upward trends in population growth have and will lead to further biodiversity loss and increasing numbers of threatened species. The need for transformative changes in consumption patterns is particularly pertinent for wealthier nations and people.

Background

Across 114 nations, the number of threatened species in the average nation is expected to increase by 14% by 2050 (McKee et al., 2004); and increased efficiency in food production is unlikely to compensate sufficiently for the negative impact of human population growth and increasing per capita consumption on biodiversity (Crist et al., 2017). Expected changes in population and income between 2010 and 2050 suggest that the environmental effects of the food system—as one example—could increase by 50–90% without substantial technological changes and dedicated mitigation (Springman et al., 2018). Globally, decreases in consumption are thus critical, recognizing that there are significant inequalities within and between countries in consumption related to food, energy, water, and other natural resources (O’Brien & Leichenko, 2010).

Aggregate consumption is a function of population size and per-capita consumption. An example of these effects at a fine scale is that households with fewer members tend to have higher per-capita consumption, with consequences for biodiversity, especially in biodiversity hotspots (Liu et al., 2003). Cities are more efficient resource-users per capita than sparsely populated areas due to economies of scale, in particular with infrastructure (EEA, 2015). On the other hand,

urbanization has also been found to increase consumption at the household scale. Specifically, the ecological footprints (an index of major consumption categories at the household level; see Chapters 2 and 3) of nineteen coastal cities across the Mediterranean reveals that per capita footprints are larger on average than parallel rural populations. The main drivers were found to be food consumption, transportation and consumption of manufactured goods (Baabou et al., 2017). In general, the co-benefits of urban systems as both source and solution of environmental effects are under-examined.

Evidence

Aggregate consumption (the product of population size and per capita consumption and waste) is undisputably a key driver of environmental degradation (Rosa et al., 2004; Dietz et al., 2007;

Ehrlich & Pringle, 2009). As one prime example, food consumption drives the agricultural sector (which covers 38% of Earth’s surface), and is as a primary source of environmental degradation and GHG emissions (both drivers of biodiversity loss). Seventy-five percent of that agricultural land is used for livestock production (Foley et al., 2011). In particular, demand for animal source foods has more than tripled over the past 50 years due to population growth and dietary change

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(Delgado, 2005; Thornton, 2010). Livestock production (grazing and feedstock) is the single largest driver of habitat loss, a pattern increasing in developing tropical countries where the majority of biological diversity resides. The projected land base required by 2050 to support livestock production in several megadiverse countries exceeds 30–50% of their current agricultural areas (Machovina et al., 2015). Some reduction in biodiversity loss can be offset through technological gains such as yield gains in agriculture due to intensification (Wirsenius et al., 2010), but these do not yet keep pace with simultaneous growth in population and income (e.g., West et al., 2014).

Changes in consumption patterns are among the most prominent elements in storylines used in scenarios that lead to achieving SDGs, including all three elements (population size, per-capita consumption, and waste). The core global studies (Roads to Rio+20, Pathways to the 1.5ºC target, and Bending the Curve—5.3.1.2) all assumed relatively low stabilized global population sizes and various scenarios of reduced over-consumption and waste. More specifically, Stehfest et al. (2009) showed that four scenarios of dietary variants, all involving reduced meat

consumption yielded diminished land-use change (and associated, non-modelled, benefits for BES) and reduced emissions and energy demand. Meanwhile, energy scenarios suggest that focusing on the energy use of sectors—not people—would lead to substantial reduction in energy demand (see McCollum et al., 2012’s energy efficient pathway).

These patterns in scenarios contain some important complexities but lack others. One key missing nuance in large-scale scenarios is the minimal representation of rebound effects (Jevons paradox), by which consumption often tends to increase in response to gains in efficiency in production or resource intensity, erasing some or all of the gains (e.g., LED lighting may be more efficient but enable much more lighting in total; more abundant energy may encourage greater consumptionand) (Alcott, 2005). Accounting for these rebound effects would make the case even clearer that increased production and efficiency are not sufficient, without also addressing consumption itself. In terms of food consumption, modeled patterns often somewhat under-represent variation within agricultural systems, and the important role dairy and foods of animal original play in childhood, maternal (during pregnancy) and elderly nutrition (FAO, 2016). For instance, few scenarios account for feedbacks between changing availability of protein affects local hunting or fishing (Brasheres et al., 2004), where wild-based and so small-scale economies, such as bushmeat provisioning, have also been identified as an important driver of biodiversity loss (Nasi et al., 2008; Fa et al., 2005). Terrestrial wildlife, especially ungulates, are a primary source of meat for millions globally. Wild meats are however an important source of childhood nutrition, without which an estimated 29% increase in children suffering from anemia would occur, leading to health, cognitive and physical deficits in poor households (Golden et al., 2011). Virtually all models do include some level of meat and fish derived proteins. Furthermore, all models related to the role of dietary changes recognize that dietary changes, such as lowering animal protein consumption do not apply to under-nourished and vulnerable populations. The general point is that lowering consumption of animal protein is

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important; and that variation aside, even the lowest impact of animal protein production typically exceed the impact of plant-based options (Clark and Tilman, 2017; Poore and Nemecek, 2018).

Waste is equally key. A large amount of food, including animal products, is wasted worldwide, e.g., roughly 30% in the U.S. when accounting for production through household waste

(Nellemann, 2009). Wasting 1 kg of feedlot-raised boneless beef is estimated to have ~24 times the effect on available calories as wasting 1 kg of wheat (~98,000 kcal versus ~4000 kcal) due to the inefficiencies of caloric and protein conversion from plant to animal biomass (West et al., 2014). Waste varies greatly between countries: food loss in India for vegetables and pork is <3 kcal per person day−1, versus ~290 kcal per person day−1 for beef in the United States.

Approximately 7 to 8 times more land is required to support this waste in the United States than in India (Machovina et al., 2015). Overall, because waste in the production cycle is so variable, even for the same food types and classes, producer-level monitoring and mitigation will be key to achieving more sustainable pathways (Poore and Nemecek, 2018).

Over-production (when not discarded to prop up prices) and associated marketing can also drive consumption: if subsidies or other forces yield an over-supply of a commodity or good, this will lower prices, and consumption of those goods and their embodied resources will tend to rise.

Producers can boost these effects strongly via advertising, which can yield self-reinforcing dynamics in consumer culture (Philibert, 1989; Berger, 2015; Isenberg, 2017).

Possible points of action

It is estimated that countering these driving forces would require incentives for increases in the efficiency of resource use of about 2% per year (Dietz et al., 2007), and no single measure or action will be sufficient. Intensification will offset some effects of consumption in the

agricultural sector, but much gain would accrue via reduction in meat consumption through demand reduction and dietary shifts (Foley et al., 2011). As with all efficiencies, some rebound effects are to be expected and addressed (e.g., increased demand that follows initial gain through efficiency) (Alcott et al., 2012).

An estimated 1.3 to 3.6 billion fewer people could be fed if diets shifted to lessen reliance on animal products, particularly resource-demanding ones (while maintaining the relative contribution of grazing systems) (Davis and D’Ordorico, 2015). Some analyses suggest that targeting Western high-income and middle-income countries would yield the largest potential gain and focus for the environmental (and health) benefits of dietary changes at a per capita level (Springman et al., 2014). Improvements in consumption patterns can likely be achieved by reducing subsidies for animal-based products, increasing those for plant-based foods, and replacing ecologically-inefficient ruminants (e.g., cattle, goats, sheep) (Machovina et al., 2015).

Research and development of plant-based meat substitutes is also a growing phenomena and potential solution (Elzerman et al., 2013; See also Springman et al., 2014; 2018; Poore and Nemecek, 2018).

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Significant targeting of waste is also an important policy target; well tested approaches include regulations for Extended Producer Responsibility whereby producers manage the waste

generated by their products (OECD, 2016).

Given the central role of advertising and marketing in boosting production, policies might seek to rein in the reach of advertising, particularly to children and for resource-intensive products.

Lastly, broader changes in consumption could be triggered by promoting alternative models of economic growth (e.g., as proposed by the World Business Council for Sustainable Development (WBCSD), 2010), which may also offer higher likelihood of achieving SDGs 2, 6, 15.