Are dietary changes the only way forward?

A few days ago I read on the news that since the introduction of the 5p carrier bag charge, there has been an approximately 50% reduction in the number of plastic bags found on beaches in the UK. Could it therefore be argued that reducing our beef consumption in the UK could be tackled through taxing the meat? 

An article from The Guardian explored this idea, reporting findings from a study by Springman et al. (2016). The authors used an agriculture-economic model 'IMPACT' to project future global consumption of various agricultural commodities by 2020 in order to analyse whether taxing these commodities, based on their greenhouse gas (GHG) emissions, could affect both GHG emissions and human health. Figure 1 illustrates the outcome of the introduction of the GHG tax, which demonstrates the dramatic reduction in GHG emissions after the tax is implemented, particularly the decrease in world GHG emissions produced from beef. Overall the study found that the introduction of tax on foods would result in a reduction of food-related GHG emissions of approximately 9% by 2020. 

Figure 1 | a. Price and GHG taxes for various commodities in US dollars per kg; b. Percentage changes in the price and consumption of each commodity with the introduction of GHG taxes; c. The changes in GHG emissions of each commodity after the introduction of the GHG tax in various parts of the world - high-income countries (HIC); low and middle income countries in Africa (AFR); America (AMR); Eastern Mediterranean (EMR); South-East Asia (SEA); and the Western Pacific (WPR).
Commodity price and GHG tax varied by commodity and region because of different GHG emissions produced by each commodity and varying management practices in the different regions, respectively.

(After Springman et al., 2016)

However, the authors stated a key limitation in the calculation of the GHG emission reduction. This was that the model did not consider all climate-carbon feedbacks, in particular for methane, which is applicable for methane-intensive foods, like beef. Another issue that could arise from the introduction of tax on GHG-intensive foods in the UK is the financial impact it could have on lower-income communities. 

The Committee on Climate Change (2008) came up with a new approach in identifying ways to reduce the GHG emissions produced by livestock agriculture (Gill et al., 2010). These were:

1) Lifestyle changes
2) Agricultural changes

3) Technological changes 

Decreasing GHG emissions through lifestyle changes has been thoroughly discussed in previous posts, i.e. dietary changes, therefore the remainder of this post will explore these other two approaches.


Agricultural changes

A previous blog post discussed how changes in the management of land use in Brazil could affect GHG emissions. As well as this proposition, changes in cattle feed is commonly considered. The 2013 State of Food and Agriculture report published by the Food and Agricultural Organisation of the United Nations (FAO) stated that one of the main sources of GHG emissions is from feed production and processing (The Guardian, 2013). The composition of feed can directly influence the volume of nitrogenous components excreted in the manure of cattle (Gill et al., 2010).

(source: synthite.com)

Miesselbrook et al. (2005) researched whether the amount of crude protein (CP) in a cattle’s diet affected the nitrogen produced by the cattle through examining the urine and faeces of cows which consume different diets. One finding was that reducing the CP content of a cattle’s diet from 19.4% to 13.6% resulted in reductions of both nitrogen excretion and urinary nitrogen excretion, 30% and 45% respectively, which indicates the possibility of dietary alterations to decrease GHG emissions. A second dietary change proposition I came across was on the ‘Science by Guff’ page on Instagram, which featured a post that stated how new research in Australia has discovered that introducing a type of dried seaweed, asparagopsis taxiformis, into cattle’s diet resulted in a dramatic decrease in methane (CH₄) emissions produced by the cattle.  Not only did they trial this on cattle but also sheep; incorporating this seaweed as 2% of the sheep’s diet led to a decrease in the production of CH₄ emissions by between 50% and 70% over a 72-day period. However, would there be a sufficient amount of seaweed to feed the global cattle and sheep population in order to reduce CH₄ emissions?

Technological changes
It could be argued that technological changes are advantageous because it implies that people would not have to change their lifestyle or diet, which is definitely favorable. According to Gill et al. (2010), a plethora of research is being done into the use and effect of nitrification inhibitors in New Zealand as this could assist in reducing GHG emissions. A study by Gillingham et al. (2015) performed a three year research programme across five sites in New Zealand to examine the effects of the nitrification inhibitor, ‘dicylandiamide’ (DCD), on soil mineral nitrogen (N) changes, nitrous oxide (N₂O) emissions and pasture dry matter production. Within New Zealand itself, N₂O emissions have increased by 23% between 1990 and 2009, largely as a result of a rise and intensification in N-fertiliser usage which is mainly attributed to dairy farms. The authors in the study found that there was an overall decrease in N₂O emissions between 2009 and 2012, accompanied by the delay of nitrification and reduction of nitrate accumulation in soils as a result of DCD application. These findings were corroborated by Ledgard et al. (2014), who carried out a similar investigation in New Zealand, where N₂O emissions also decreased over a three year period through the use of DCD. An additional advantage the study noted was that a decrease in N loss through emissions mean that more N remained in the soils which could result in greater plant growth.

However, both studies observe that the emissions of N₂O appear to be influenced by climatic changes, primarily temperature and precipitation, as this can affect the DCD residency time in soils. This creates a limitation in the use of this particular nitrification inhibitor as it suggests that success from DCD use may only occur in particular countries or regions with a certain climate. In addition, DCD is extremely expensive to use and so may be too costly for large-scale agricultural usage (Zerulla et al., 2001). 

What is the answer?

In my opinion, the root of the problem is that society is not fully aware of the impacts that cattle rearing has on the environment and how greatly it contributes to climate change; maybe if society was more informed through the government or environmental organisations, lifestyle changes would be more prevalent. However, as many people are reluctant to changing their behavior, perhaps these alternative options are the way forward.