An analysis of the relationship between income and proteins consumption

To sustain a growing population and food demand, modern agriculture relied on technologies, irrigation and fertilizers application, designed to increase crop yields and production. However, these practices have environmental drawbacks that are placing greater pressure on the planet’s finite resources. The Millennium Ecosystem Assessment has warned that 15 out of the 24 of the world's ecosystem services are being degraded or used unsustainably (MEA, 2005). In general, food production and environmental problems are interdependent and affect one another: contemporary agriculture practices result in environmental problems that, in turn, threat our ability to produce safe and sustainable food.
The environmental impacts of food production include resource depletion and pollution on all scale levels from local to global (Aiking, 2011). Some of these issues includes water resources depletion, energy consumption, chemical fertilizer and pesticides application, waste generation, land degradation, deforestation and climate change. Agriculture is the largest single user of fresh water, accounting for about 70% of current human water use (FAO). Critical water issues exacerbated by agricultural practices includes the pollution of surface and groundwater sources, over-drafting of aquifers, water-logging and salinization of soils, wetlands loss and runoff, evaporation and leakage from irrigation system (Marlow et al., 2009). The food production and supply chain accounts for about 30% of total global energy consumption (UNESCO, 2012). The overuse of fertilizers has resulted in surface and groundwater contamination, air pollution and decrease in biodiversity. While the rates of application of chemical fertilizers have increased about 10% yearly since 1950s, pesticides use has grown as much as 33-fold only in the US since 1940s. Concerns over the pesticide use includes residues in food that could affect human health, water contamination, loss of biodiversity and resistance in pests (Marlow et al., 2009).

In the literature, there appears to be a link between dietary preference, agricultural production and environmental degradation. It has been suggested that the environmental burden of vegetarian foods is relatively low than animal products. For instance, in the paper of Reijnders and Soret (2003), the data presented evinces that vegetarian alternatives for meat, cheese and fish have a relatively lower environmental impact when primary production and processing are considered. A different study (Marlow et al.,2009) provides evidence for the same outcome: the effect ratios for water use efficiency, energy use efficiency, pesticide use efficiency and fertilizer use efficiency show a greater ecological cost effectiveness for plant-based diets compared to nonvegetarian diets. In another research (Baroni et al., 2007), whose aim was to compare different environmental impacts resulting from different dietary patterns (omnivorous, vegetarian, vegan) and methods of production (conventional farming and organic agriculture) through a Life Cycle Assessment methodology, the omnivorous diet turns out to have the greatest environmental impact, while the vegan the lower.
Perhaps the most important impact is on global warming. The agri-food sector is a major contributor to climate change. The IPCC estimates that emission from AFOLU (agriculture, forestry and other land use) contribute to around 24% of the total emissions (Smith et al., 2014). The methane emissions of agriculture come from ruminant livestock such as dairy cows, beef or sheep, while nitrous oxide emissions come largely from organic and inorganic fertilizers use, from tillage of soil and deforestation for farming use (Lang et al, 2009). According to a report of the FAO (2013), livestock emissions account for 14.5 % of human induced GHGs. However, we can find large differences across studies in the estimates of the impact, because of “the exclusion or inclusion of emission due to deforestation and land use change” (UNEP, 2012, p.4). Carbon dioxide is only a small component of the emissions of animal agriculture. Methane and nitrous oxide play a more important role. The main source of CH4 are enteric fermentation of ruminants and releases from manure, which also emits N2O. The gases emitted in animal agriculture are powerful greenhouse gases, with a global warming potential (GWP) of 25 for methane and 296 for nitrous oxide.

There are other important environmental impacts associated with meat production. The inefficient conversion of plant protein into animal protein makes meat responsible for different environmental pressures. Cattle are the least efficient converters of feed to meat: as little as 3% of gross energy in feed are converted into energy in food; thus, 89-97% of gross energy contained in the feed and 80-96% of all protein in cereal and leguminous grains fed to animal are not converted to edible protein and fat (Smil, 2002). Moreover, meat production (and cattle feeding in particular) is one of the most water-intensive economic sector: the overall requirement is 20 tonnes of water per kg of edible beef (Smil, 2002). In addition, water often ends up contaminated and together with the waste generated by animals, represents a major source of regional and local environmental pollution (eutrophication, acidification, leaching of nitrate, accumulation of phosphorus and heavy metals).
In turn, global climate change is considered a threat to the stability of the agri-food sector. The commonly presented scenarios include impacts such as increase of extreme climate events (drought and fooding), rising sea levels, shifting temperature and growing areas for particular crops zones, harvest loss and wider spread of disease. In spite of the fact that impacts could bring some advantage in specific regions, the overall effect on agriculture is negative (Lang et al., 2009). The Stern Review commissioned by the UK Government and published in 2006 concludes that doing nothing to reduce GHG would mean costs, on account of climate change damage, equivalent to 10,9% reduction in global per capita consumption, while the costs of action to stabilise the CO2 concentration at 550 ppm would be about 1% of gross world product. It suggests that strong and early action to reduce emission is economically viable and efficient (Perman et al., 2011).