Diet for the planet: cut the carbon not the carbs!

Mayu Suzuki updated
By Mayu Suzuki, GLOBUS Correspondent

The author would like to thank Dr. Alastair Smith, Senior Teaching Fellow of the Global Sustainable Development Division at the University of Warwick, for his valued comments

On first visit to a supermarket in the United Kingdom, I was surprised to find unfamiliar food sourced from a variety of countries. Born in Japan, I was used to domestically produced food, occasionally sourced from neighbouring countries. It was exciting to try out prosciutto from Italy and blackberries from Spain. Thanks to globalisation, we can extend our culinary curiosity to the fullest these days.

At the same time, this observation raises environmental concerns; the general consensus is that importing food from overseas generates more greenhouse gasses than food grown locally. A study conducted by the National Sustainable Agriculture Information Service (ATTRA) suggests an increasing trend of sourcing food from outside national boundaries, so that multinational firms can stack shelves at consistently low prices. In 1961, the volume of world agricultural trade was approximately 200 million tons. Two decades later, this volume had quadrupled [1]. Nevertheless, thanks to technological advancement, we have more energy efficient means of transportation, not to mention that ocean shipping is far less energy intensive than trucking because a large quantity is transported together [2].

Surprisingly, most carbon emissions in food supply chain are, in fact, generated during the production phase, not transport. [3] Studies suggest that, alone, the geographic location of production process does not necessarily indicate the total cumulative volume of carbon emissions traced to a single product. For example, the estimated carbon footprint of roses exported to the UK from Kenya and Netherlands vary significantly; Dutch roses produce significantly more emissions owing to the amount of fossil fuelled electricity used to operate glasshouse in contrast to geothermal energy used for Kenyan greenhouses [4]. Therefore, the degree of eco-friendliness of a food item is profoundly determined by factors such as the efficiency of the producer, what is produced, seasonality, climate and sources of energy. Regarding productivity, small local farms may create more emissions than large overseas farms [5]. Nevertheless, transporting imported products from the shipyards to warehouses and branch stores incurs additional emissions. Estimating the carbon emissions attributed to a single product is, hence, increasingly complicated.

The question is: how can we reduce our own carbon footprints?

The first action – and I think the easiest – we can make is to shop at a supermarket within walking distance. Driving a car to do the weekly shopping may emit more carbon dioxide in the air than consuming imported food. While the average passenger vehicle emits about 404 grams of carbon dioxide per mile [6], less than 300 grams of carbon dioxide per mile (TEU) is emitted for transporting food by ship, or about 150 grams per mile (TEU) for railway transport [2]. Considering that most freights come in a large quantity, your drive will have a significant impact in terms of carbon emissions.

However, it is still worth noting that the choices we make as consumers are still relevant. Even though carbon emissions from food production is often too complex to measure as many factors come into play, the country of origin or specific trademark can signal the production processes behind a given product. Many commercial agricultural projects on rainforest lands inhibit the ability of the forest to photosynthesise, whereby plants absorb atmospheric carbon dioxide and release oxygen. For instance, a recent simulation in Indonesia indicates that the implementation of the Roundtable on Sustainable Palm Oil (RSPO) certification reduced deforestation rates from crop cultivation by 33%. RSPO certification guides customers towards a supply of palm oil that led to less forest loss [7]. On the other hand, one study shows that there is a land-use carbon footprint of 1440 kg carbon dioxide equivalent (CO2e) for every kilogram of beef and 1603 kg CO2e for every kilogram of shrimp produced on lands formerly occupied by mangroves in Latin American countries and Indonesia [8]. This reality is not popular among consumers as currently there is no trademarks or certificates to promote the protection of mangrove forests. The contrast clearly signifies the importance introducing measures to regulate harmful production practices. The incentives for producers are amplified with increased consumer awareness.

Another way is to reduce food waste. Throwing food away means all those emissions are released to the atmosphere to no good end. Worse still, food waste can cause more greenhouse emissions through the handling of landfill litter. There are dozens of other ethical reasons not to waste food. Environmental consequences should not be overlooked. At present, the University of Warwick does not have a fully integrated food recycling system. Although this issue is being investigated, food waste is currently put in general waste bins, increasing the volume of landfill. By contrast, the Warwick Student Union collects used cooking oil and food waste, which are then turned into biodiesel and biogas respectively by Olleco [12]. This is an example of a sustainable recycling model and should be put into practice in wider societies.

Last, but not least, more emphasis needs to be placed on reducing the consumption of red meat. Complementary to the recent release of the Intergovernmental Panel on Climate Change, many scientists stressed the need to eat less beef, lamb and dairy products [9]. As part of their digestive system, ruminants produce methane, a more potent greenhouse gas than carbon dioxide. A survey conducted by Waitrose revealed that even though pure vegetarians make up less than an estimated 10% of the population of the United Kingdom, approximately one-third is turning to a more plant-based, or flexitarian, diet [10]. Turning to veganism completely may perhaps seem as if a radical change is required. But the growing trend of flexitarian diet can still contribute to cutting down our meat consumptions so that the amount of livestock that collectively add to carbon emissions can be reduced.  There is a positive correlation between meat consumption and GDP per capita (constant 2011 international $) [11]. Although a global transition may not occur overnight, slow market recalibration of those with economic capacity to invest in alternative diets and food systems will help offset the growing meat consumption in other parts of the developing world.

Aiming for a zero-carbon economy is no simple task. The complexity of the food supply chain calls for governments and international institutions such as the World Trade Organisations to take responsibility. They implement, for instance, measures such as integrated production protocols and facilitate the introduction of green transportation. At a local scale, individuals can work towards establishing sustainable diets as a societal norm. Furthermore, systems of food waste disposal need to be reviewed. As highlighted in the example above, implementing trademarks for sustainable products can increase consumer awareness. Consumer choice is key. No matter how small, your actions take the first steps towards our greener future.



[1]  ATTRA – National Sustainable Agriculture Information Service, (2008). Food Miles: Background and Marketing (

[2] Corbett, J., Winebrake, J., Hatcher, J., and Farrell, A., (2007). Emissions Analysis of Freight Transport Comparing Land-Side and Water-Side Short-Sea Routes: Development and Demonstration of a Freight Routing and Emissions Analysis Tool (FREAT) FINAL REPORT. U.S. Department of Transportation, Research and Special Programs Administration (

[3] Alessandro K. Cerutti, Simone Contu, Fulvio Ardente, Dario Donno, and Gabriele L. Beccaro. (2016) ‘Carbon footprint in green public procurement: Policy evaluation from a case study in the food sector’, Food Policy, vol. 58, pp. 82-93 (

[4] Brenton, P., Edwards-Jones, G., and Jensen, M. (2009) ‘Carbon Labelling and Low-Income Country Exports: A Review of the Development Issues’, Development Policy Review, vol. 27, no. 3, pp. 243-267 (

[5] Steven, L. and Dubner, S. J., (2009). Superfreakonomics. William Morrow and Company.


[7] Kimberly M. Carlson, Robert Heilmayr, Holly K. Gibbs, Praveen Noojipady, David N. Burns, Douglas C. Morton, Nathalie F. Walker, Gary D. Paoli, and Claire Kremen (2017). ‘Effect of oil palm sustainability certification on deforestation and fire in Indonesia’, Proceedings of the National Academy of Science of the United States of America, vol. 115, no. 1, pp. 121-126 (

[8] Boone Kauffman J, Arifanti V, Hernández Trejo H, del Carmen Jesús García M, Norfolk J, Cifuentes M, Hadriyanto D, and Murdiyarso D, (2017). ‘The jumbo carbon footprint of a shrimp: carbon losses from mangrove deforestation’, Frontiers in Ecology and the Environment, vol. 15, no. 4, pp. 183-188 (



[11] Hannah Ritchie and Max Roser (2018) – “Meat and Seafood Production & Consumption”. Published online at Retrieved from:

Header Image: Photo by 12019 on Pixabay

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