Vegetarianism - is this really necessary to save the planet?

I realised the other day that I have not eaten any beef for over 3 months now… considering how much I love a steak, I am quite impressed with myself! I have, however, been craving a chilli con carne for a while now. So, my housemate and I decided to make a vegetarian chilli using a Jamie Oliver recipe. It was actually really tasty (see the photo below)! Replacing this classic meat dish with a vegetarian one, along with comments on previous posts asking whether society should consider a completely vegetarian diet to combat greenhouse gas (GHG) emissions, has made me want to investigate the notion of vegetarianism and climate change.

(source: Laura Thrower)

There is a plethora of news articles reporting on this subject. The Guardian (2016) discusses research performed by scientists at the Oxford Martin School, who discover that the global adoption of a vegetarian diet by 2050 would result in a 63% reduction in GHG emissions. A few of the reasons behind this include the reduction in consumption of water and grains by animals, and the decrease of methane (CH₄) production. Furthermore, a report by The Independent (2016) made a concluding remark that if the UK population went vegetarian, the UK's GHG footprint could be cut by 25%. 

Various studies also examine the idea of vegetarianism and its environmental benefits. A study by Stehfest et al. (2009) investigated the differences in GHG emissions in four alternative dietary variants (no ruminant meat (cattle, goat and sheep), no meat, no animal products and healthy diet) using the integrated assessment IMAGE 2.4 model. One finding was that that producing 100kg of protein from beef requires 0.6 hectares (ha) of cropland, whereas producing 100kg of protein from pulses only requires 0.25ha of cropland. This is partly as a result of a large reduction in the usage of feed crops when producing pulses as opposed to rearing cattle. Furthermore, this reduction in cattle required could also mean that a considerable amount of grain would become available which Carlsson-Kanyama (1998) report could be used for human consumption and so improve the supply of food to a growing world population. 

Moreover, a study by Scarborough et al. (2014) performed research in a similar field, whereby the authors estimated the GHG emissions produced by four different diet groups; these were vegans, vegetarians, fish-eaters and meat-eaters. The study found substantial reductions in CO₂ emissions (CO₂e) through dietary changes; changing from a high-meat to a low-meat diet was found to reduce an individual's carbon footprint by 920kg of CO₂e per year, and changing from a high-meat to a vegetarian diet reduced an individual's carbon footprint by a staggering 1,230kg of CO₂e per year. To place this into context, an individual's carbon footprint flight from London to New York is approximately 960kg of CO₂e. I feel comparing emissions produced from eating meat with more well-known GHG-producing activities like driving cars and travelling by airplanes is definitely an effective way of getting the message across that our eating habits are severely polluting the planet.

To visualise the substantial differences between meat and other non-meat sources of protein, Table 1, from Gonzalez et al. (2010), is displayed below. This study involved measuring the energy use and GHG emissions of 84 common foods. I have highlighted the results for beef, chicken and beans. Obviously beef has the highest protein content. However when you compare its GHG emissions and protein delivery efficiency to beans, it is clear the sheer environmental advantages of choosing a non-meat option. Furthermore it is evident that chicken is a good alternative to beef as the study founds it produces 24.3kg of CO₂ equivalent per kilogram less than beef does.

Figure 1 | Protein content, energy use, GHG emissions, protein delivery efficiency energy and protein delivery efficiency GHG measurements of a variety of foods.

(After Gonzalez et al., 2010)

Of course, changing from an omnivorous diet to a vegetarian one can be particularly challenging - personally I do not think I could do it. Therefore I have additionally examined other options rather than shifting to a completely vegetarian diet. Other studies I have read demonstrate benefits of replacing ruminant meats with less GHG intensive meats. For example, despite Stehfest et al. (2009) demonstrating that a non-meat diet is much less land intensive, their no ruminant meat scenario showed a substantial reduction in agricultural area, giving rise to available land for other purposes and/or the regrowth of vegetation, which would provide a carbon sink and CO₂ uptake. 

Additionally, research by Berners-Lee et al. (2011) quantified GHG emissions produced by different types of diet based on dietary data from the UK and USA, and GHG emissions. Although the study found a GHG saving of 22% from changing from an omnivorous diet to a vegetarian diet, the authors did draw a conclusion that choosing chicken, for example, as a replacement to ruminant meat is efficient because it produces much less GHG emissions. Statistics show that beef produces almost 300kg of CO₂ equivalent per kilogram of protein produced. In contrast, chicken produces less than 100kg of CO₂ equivalent per kilogram of protein produced. Reasons for this include that chickens require far less land to be farmed on as well as the amount of grain they require for feed is dramatically lower than for cattle. Furthermore, Berners-Lee et al. (2011) suggest buying products produced from less GHG-intensive farming practices could be another sufficient way of changing lifestyle choices to reduce GHG emissions without converting to vegetarianism. 

A concluding remark from this blog post could perhaps be the suggestion of people going vegetarian a couple of days a week as this may be more achievable for those who would struggle to stop eating meet completely (AKA me). Ideas like 'Meat Free Mondays' are great options too - I have to say the recipes on their website look delicious!

(source: meatfreemondays.com)