Tracking the carbon footprint of what you eat

Yesterday I received an email from my Auntie with a link to the website 'Less Meat Less Heat'. They are an organisation which aims to reduce the global meat consumption in order to reduce greenhouse gas (GHG) emissions and tackle climate change. The facts section of the website is extremely informative also - one fact that really jumped out at me was that the water footprint of eating a burger and a month of daily showers is the same! The organisation has also created an app called 'The Climatarian Challenge' where you can track your carbon footprint based on the food you eat for 30 days relative to a monthly budget of 80kg of carbon. Carbon footprints are becoming acknowledged as both an indicator and management technique of GHG and carbon emissions (Wright et al., 2011). It is often a term used in news reports as it is a commonly recognised phrase within society. For example I remember reading a newspaper headline in The Guardian at the start of November entitled 'Your carbon footprint destroys 30 square metres of Arctic sea ice a year'. The phrase 'your carbon footprint' most definitely catches a reader's attention as it places the responsibility of reducing GHG and carbon emissions on the individual rather than a country or the globe.

Anyway I decided to download 'The Climatarian Challenge' app yesterday and have started tracking my consumption (it is downloadable on either the Apple iOS app store or Google Play). It is ever so easy to use and what I love is the new facts you get told nearly every time you fill in a meal. I will let you know in 30 days whether I can keep within the budget!

(source: green.nd.edu)

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)

Beef production in Brazil

One of the facts I picked up on in the documentary 'Before the Flood' was that beef is the foremost reason for tropical deforestation. Tropical forests cover 7% of the land and are home to 50% of all living things on the planet. The Amazon is an example of one of these tropical forests and it is notably referred to as 'the lungs of the planet'. It is located in South America and spreads across many countries, one of which is Brazil.

Figure 1 | Map of South America outlining the Amazon. 

(source: wwf.panda.org)

Brazil is a leading global producer and exporter of beef, and has the world's largest commercial cattle herd. In order to produce these vast quantities of beef, huge amounts of pastureland are required. A study I read stated that between 2002 and 2004, a surge in deforestation of the Brazilian Amazonia occurred which is strongly related to the creation of pastureland - this is the dominant course of deforestation in the Brazilian Amazonia.

McAlpine et al. (2009) investigated the effects of beef consumption, in order to attempt to raise awareness of the issue, through using three case studies from three different countries, one of which was Brazil. Figure 2 taken from the paper illustrates the extent to which cattle expansion is occurring in Amazonia itself compared with the rest of Brazil.

Figure 2 | This graph illustrates the recent surge of cattle expansion in Amazonia. 

(After McAlpine et al., 2009)

This study noted previous work which had simulated the atmospheric response that would occur if the entirety of the Amazon was replaced by pastureland. The results of this suggest that rainfall over the region would decrease, possibly as a result of decreases in evapotranspiration, and higher temperatures. In addition to this, even greater levels of biodiversity loss would occur. This indirectly demonstrates the consequences of our global meat consumption. Furthermore, as global beef consumption grows more affordable in economically emerging countries, such as China (McAlpine et al., 2009), these simulations become even more concerning as more and more of the Amazon will need to be deforested to meet demand. Another study by Cederberg et al. (2009) investigated the greenhouse gas (GHG) emissions life cycle, and the use of energy and land from the beef that is exported from Brazil to Europe. A statistic that was uncovered was that GHG emissions produced from the primary production of Brazilian beef is at least 30-40% higher compared with the current European production levels. This emphasises Brazil as a key GHG emitter through its cattle herds. 

In great contrast to this blogpost so far, a paper by de Oliveira Silva et al. (2016) analysed the relationship between beef demand, production, intensification, deforestation and soil carbon dynamics. Using their decoupled livestock-deforestation (DLD) scenario, the paper argues a decrease in beef demand may actually increase GHG emissions in the Cerrado grazing system (this area accounts for about 34% of Brazil's beef production). The study comes to this conclusion that a decrease in demand would lead to smaller cattle herds required, which means less grass is needed to be produced for feed. Therefore there is a decrease in people's incentive to increase, or even maintain, productivity of the pasture which would cause the pastures to degrade and so result in a decrease in soil organic matter. This leads to a decrease in soil carbon stocks and so the pasture would no longer be an efficient carbon sink, which would increasing atmospheric carbon levels.

Yes, this makes logical, scientific sense. However, it is very important to note that this DLD scenario carries the assumption that deforestation rates are controlled by effective policy. This raises a key question - will effective policy be implemented? According to McAlpine et al. (2009), the Brazilian government was heavily involved in eliminating foot-and-mouth disease to increase their exports of beef. Furthermore, branches of the Brazilian government promote building roads in order to access remote parts of Amazonia to use for cattle grazing. Based on this past knowledge of the government, in my opinion, it seems unlikely that effective policy would actually be implemented.

So what is the solution? Cederberg et al. (2009) states that improved land management is necessary to reduce GHG emissions from cattle. Interestingly, a study by Figueiredo et al. (2016) examined the GHG emissions and the carbon footprint of cattle in three sites in Brazil which all use differing production techniques. Through their investigation, the authors were able to propose alternative land-use solutions to reduce GHG emissions. One of their solutions was to convert degraded pasture to well-managed pasture because their study showed that this may reduce the carbon footprint from beef cattle through a more efficient system. A second solution was through the adoption of a crop-livestock-forest  integrated system (CLFIS) where cattle grazing would be integrated with the production of trees, grains and grasses. It is stated that this could offset cattle emissions, and perhaps even provide a valuable carbon sink. 

Perhaps improving the management of both cattle and the land they require is the way forward. However, ideas, such as those suggested by Figueiredo et al. (2016), could take years to implement. Nevertheless, it is without a doubt that cattle-rearing is a significant problem both in terms of the substantial volume of GHGs cattle emit as well as its impact on the Amazon through deforestation. 

A question I wish for you to ask yourselves is this - is it really worth destroying the Amazon, one of the greatest biodiversity hotspots and crucial carbon sinks on the planet, for some meat?

(source: travelinnate.com)

'Before the Flood'

I am sure many of you have either heard about or watched the new documentary 'Before the Flood' - I watched it the other day and found it so interesting but also extremely shocking and scary about what we are doing to our planet. I was really pleased when the link between cattle and climate change was mentioned and learnt even more about the subject (it is discussed about 50 minutes into the documentary if you want to skip to that bit!). It is definitely worth a watch for anyone interested in climate change (and Leo fans).

Sadly it is only available to watch until the end of today so get going!