Agriculture and Food Production
Agriculture is assessed to contribute 10-12% of all human generated GHG emissions (Smith et al., 2007, p.63). However, additional energy required to transport, process, package, store, distribute, prepare, consume and dispose of food takes food supply chain GHG emissions to 17-32% of all GHG emissions (Bellarby et al., 2008, p.5). Energy demands from fossil fuels, their emissions, further exacerbated by deforestation to make way for additional agricultural land, all exacerbate this effect. The GHG impact from livestock production is more significant as methane is 25 times more potent as a GHG than carbon dioxide, with nitrous oxide (from the fertiliser used to grow crops to feed both humans and livestock) 298 times more potent (Solomon et al., 2007, p.33).
A regularly cited UN study published in 2006 (titled ‘Livestock’s Long Shadow) estimates that livestock alone contribute up to 18% of the earth’s GHG emissions (Steinfeld et al., 2006, p.112); however, other studies estimate the contribution to be much lower at around 3% (Pitesky et al., 2009, p.2). The higher end figure puts it at odds with other figures of GHG emissions; however, despite this variation livestock are considered a resource demanding and environmentally damaging aspect of the food chain for the following reasons: energy input for livestock production is twelve times that of plant production; livestock account for large amounts of GHG emissions; livestock use 78% of agricultural land, which is then unavailable for arable farming; making land suitable for grazing usually involves the destruction of non-agricultural habitats (such as rainforests); livestock have a detrimental effect on soil quality (meaning more land is required to be cleared); and finally, water pollution from livestock manure is three time the level contributed by humans and high in environmentally damaging compounds (Baldwin, 2015, p50-53). The impact is primarily from ruminants farmed for meat and dairy products, with pig and poultry less damaging to the environment. The environmental cost of livestock production is further exacerbated by the additional costs of arable farming required to produce animal feed (fertiliser use, antibiotics, carbon footprint). The use of feedlots, where many of the issues surrounding livestock’s negative impact on sustainability emanate, is more prevalent in the US, where 97% of beef is finished on a feedlot (Lin, 2016). There is no available data on feedlot use in the UK, if in use at all. However, the response from pressure groups to the discovery of a feedlot-style farm in Lincolnshire in 2013, suggests the practice is not common or existent in the UK (Compassion, 2013).
Despite the environmental impact of livestock there are many reasons why livestock production is beneficial to other aspects of sustainability. Moderate quantities of quality animal protein is beneficial to our health (Eisler et al., 2014, p.32), ruminant grazing plays an important role in sustaining prairie and grasslands (Reynolds et al., 2015, p.1378) and the use of manure reduces the requirement for chemical fertiliser (EBLEX, 2009, p.19). The livestock industry also plays a key role in rural communities around the world, in the UK it employs a quarter of the agricultural workforce (around 100,000 people) and generates £3bn of revenue (EBLEX, 2009, p.19).
Strategies that reduce the impact of livestock include: increasing animal feed not digestible by humans; regionally and culturally appropriate livestock; animal husbandry; animal feeds that increase digestive microbial activity; eating smaller amounts of better quality meat; taking a life cycle approach to measuring costs and benefits; manure management (e.g. anaerobic digestion which reduces GHG emissions and recovers energy); land management; making stock breed longer; making stock more fertile and making livestock more efficient at producing meat (Eisler et al., 2014, p.32-34, Baldwin, 2015, p.52 and EBLEX, 2009, p.18-19 and p.33). Strategies that focus on the animal must, however, consider second order effects as a result of selective breeding. The selective breeding of livestock for economic reasons (although in the context of this study could include sustainability reasons) has had a negative effect on biodiversity. This is evident in intra-species diversity (the ‘gene pool’ within a species) and inter-species diversity (the number of different species) where 90% of meat consumed globally is derived from fourteen species of animal whose individual genetic make-up is becoming narrower (Steinfeld et al., 2006, p.184 and p.208). Biodiversity loss has seen genetic traits that provide resiliency against environmental changes and disease bred out in favour of traits that make animals and plants more economically productive, this makes our food chain vulnerable.
 Baldwin (2015, p50-53) states livestock are responsible for 14.5% of all our GHG emissions and 60% of all our methane emissions, although is seen with the figures for overall GHG emissions, they are open for debate.
 Animals with four stomachs such as cows, sheep, deer, goats and bison.
 The grazing and release of manure on grasslands and prairies unsuitable for arable farming helps promote health and biodiversity in ecosystems that cover more than 25% of the earth’s service and act as a significant carbon sink where their grazing.
 In the UK, only 40% of agricultural land is suitable for arable farming, with the remaining 60% grassland available for livestock production.