Home > Articles > Reducing Food-Related Greenhouse Gas Emissions Through Modification of Human Diet

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Renee Cosme | January 24, 2017

 

Introduction

Global food production typically emits greenhouse gases (GHGs)—such as CO2, nitrous oxides, and methane—due to activities such as agricultural production (e.g. fertilizer manufacturing, deforestation), food processing (e.g. cooking, refrigeration), and waste disposal.

In 2008, the global food system released 9,800 to 16,900 megatons of CO2-equivalent into the atmosphere as a result of agricultural production, land-use changes, and deforestation. In fact, according to Tilman et al. (2014), global agriculture and food production emit over 25% of global GHGs.

By 2050, with the global population projected to reach 9.6 billion people, there will be an increased demand for large-scale food production, as well as shifts in dietary preferences. In fact, as a result of urbanization and increased rates of food production, dietary preferences have already shifted, along with an increased consumption of calories, especially in developing countries. Economic prosperity correlates with increased protein consumption, such that in 2009, the per-capita demand for meat in the 15 richest nations was 750% greater than in the 24 poorest nations. Meat production is energy intensive and can emit more GHGs compared to production of other foods, such as certain produce or non-meat proteins.

By 2050, Alexandratos et al. (2012) predict that the average global calorie availability could increase up to 3,070 kilocalories (k⋅cal) per person, which would require a 60% increase in global agricultural production compared to 2005/07 rates. Moreover, by 2050, if the global population reaches 9.6 billion people, Bajzelj et al. (2014) predict that food consumption per capita would increase to 2710 kcal per day (k⋅cal⋅d-1). In such a situation, if appropriate GHG emission mitigation strategies in food production are neither developed nor implemented, large-scale cropland development and livestock intensification may increase food-related GHG emissions by approximately 77% due to increased deforestation rates, use of agricultural technologies, and livestock activity.  Unless sustainable, appropriate actions are taken, the increased demand for global food production will enhance its contribution to global GHG emissions, exacerbating global climate change.

Several studies have proposed that improving the balance and health of human diets worldwide may reduce food-related GHG emissions, alongside other solutions such as reducing food waste or encouraging efficient, sustainable food production. This article will discuss improving human diet as a solution to reduce food-related GHG emissions, with recommendations that this solution may be more effective if other solutions were considered and adopted as well.

 

Improving Human Diets Can Contribute to Reducing Food-Related Global GHG Emissions

In addition to promoting a healthier lifestyle and prevention of chronic diseases, promoting a healthy diet which encourages reduced meat and ‘empty calorie’ consumption—from refined sugars, oils, and alcohols—may result in food production that is less energy intensive, thus emitting reduced concentrations of GHGs relative to current emission levels.

By 2050, Tilman et al. (2014) estimated that the average human diet might consist of 15% more calories than 2009 consumption values, with high consumption rates of red meats (i.e. poultry, pork, ruminant animals), seafood, and dairy, and decreased servings of fruits, vegetables, and plant protein.  This dietary shift will result in increased production of livestock and crops, and may ultimately increase global GHG emissions due to food production by 86% by 2050. Alternatively, the same study observed that adopting Mediterranean, vegetarian, and pescatarian diets [See Note 1] might reduce food-related global per capita GHG emissions by 30% to 55% by 2050, with no net GHG emissions from food production by that time. These diets primarily consist of food items that generally require less energy and production (i.e. certain fruits and vegetables) compared to meat-based protein (i.e. beef, poultry, pork), which thus produce fewer GHG emissions than livestock production.

At a national scale, another study, which looked at UK dietary survey data, found that if the average UK diet for men and women were altered to comply with The World Health Organization’s (WHO) dietary guidelines, it could significantly reduce diet-associated GHG emissions in the UK by 20% to 40%. Green et al. (2015) argue that reducing diet-based GHG emissions in the UK is feasible, because it requires adopting a diet that does not significantly differ from the current average diets among UK men and women, and would be accepted by the general population. A diet that complies with WHO’s dietary guidelines and reduces diet-based GHG emissions generally requires increased consumptions of water, tea, cereal (grain), vegetables, and fruits; and smaller servings of red meat, dairy products, eggs, sweet/savory snacks, and soft drinks.

It’s important to consider that certain food items regarded as ‘healthy’ are capable of causing more GHG emissions compared to a selection of food items that are considered ‘unhealthy’. For example, in Green et al.’s (2015) study, they observed that tomatoes caused more emissions in comparison to certain food items that contain sugars, such as sweet spreads. Policymakers should clearly identify which food items may appropriately constitute an improved dietary standard that is simultaneously healthy and capable of reducing less food-related GHG emissions.

Moreover, policy makers should consider that massive, sudden changes in dietary standards might not be nutritionally balanced or well received by the general population, even if it guarantees a reduction in food-related GHG emissions. For instance, a plant-based (i.e. vegan) diet may significantly contribute to reducing GHGs, but the general population may not be receptive to adapt the practice.

 

Complementary Solutions to Further Reduce Food-Related Global GHG Emissions

Solely focusing on improving global dietary standards is not an effective strategy to reduce food-related GHG emissions, because there are many components in global food production that contribute to this net emission value. Policy makers may develop or adopt a combination of demand-side and supply-side measures to simultaneously tackle issues in food production, food-related GHG emissions, and even food security. Demand-side measures address emissions in agricultural production, bioenergy, forestry, and livestock. On the other hand, supply-side measures address emissions in food waste, food supply chains, and diet-based sources (as discussed in this article). The tables below provide numerous examples of each measure.

 

Table 1. Examples of demand-side measures.

Measure Example/s
Agricultural production Encourage farmers to practice sustainable farming methods, such as no-till farming or crop rotation, which can enhance soil nutrients and carbon sequestration.
Bioenergy Support, invest, and fund scientific research, which investigate biofuel usage for sustainable food/agricultural production.
Forestry Develop monitoring programs to track forestry activity over time, to ultimately prevent large rates of deforestation.
Livestock Encourage efficient use/disposal/processing of fertilizer (manure), irrigation, animal feed, while promoting consistent management of pasture lands.

 

 

Table 2. Examples of supply-side measures.

Measure Example
Food waste Promote the conversion of food/agricultural waste into compost or useable biofuels via large-scale bioreactors that promote anaerobic digestion.
Food supply chains Strengthen international relations between developed and developing nations, where more prosperous nations (whose GDP per capita is over >$4000) provides resources that can properly support impoverished nations.
Dietary standards Encourage a dietary standard, which contains increased servings of fruits/vegetables, grains, alternative proteins, and decreased consumption of red meat proteins.

 

Ultimately, policy makers should create an agenda that best suits the population they are helping, one which would ideally meet their needs and desires with food production. For example, policymakers may prioritize developing a nutritious dietary standard over food-related GHG mitigation for impoverished populations.

 

Conclusion

While several studies suggested that improving dietary standards can reduce food-related GHG emissions at a global or national scale, this approach alone is not enough to significantly reduce global GHG emissions by 2050. Instead, this approach must be complemented with other supply- or demand-side measures, depending on the desires, needs, and priorities of the specific observed population.  By adopting several approaches, policy makers can hope to develop an agenda that may efficiently tackle global GHG mitigation, food insecurity, and unbalanced, unhealthy dietary standards.

Renee Cosme is a Graduate Fellow at The Climate Institute.

PDF version with references available here.

Notes

Mediterranean diets primarily consist of fruits, vegetables, and seafood, with moderate amounts of red meats such as pork, poultry, or beef (grains, sugars, oils, dairy, and eggs are also consumed). Vegetarian diets primarily consist of vegetables and fruits, with less than one serving of animal-based protein per month. Pescetarian diets are vegetarian diets, which include seafood consumption.