By Trevor McCoy

Our global food system carries a substantial carbon footprint, but you might not know that if you aren’t a climate scientist. While calculating exactly how much carbon is emitted by the entire food system would be impossibly complicated, experts have created emissions estimates for different sections of our food system, especially food’s greatest source of carbon emissions, agriculture.

In 2014, the Intergovernmental Panel on Climate Change (IPCC), an international group of scientists and experts that produces reports on climate change for the United Nations, listed Agriculture, Forestry, and Other Land Use (AFOLU) as contributing 24% of our global carbon emissions.¹ By comparison, the IPCC calculated that all of land, sea, and air transportation combined represent 14% of global emissions.

It is already difficult to fully understand the process that takes place when exhaust from a car’s tailpipe makes its way into the atmosphere and affects our climate, but it is even more complex to understand how something like agriculture or forestry could contribute to global warming. Figure 1 breaks down AFOLU into its components, illustrating their contributions to climate change.

Figure 1

The IPCC has broken up AFOLU’s carbon footprint into 11 major sections. Although this graph can seem complicated, with a little guidance it is easy to understand. Let’s start by looking at the big yellow section, “Enteric Fermentation.” Although enteric fermentation might be a foreign concept, it’s just the way certain animals like cows or sheep (known as ruminants) digest their food, which is a process that is very different from the way humans digest food. These animals produce significant amounts of methane (CH₄), a greenhouse gas that has substantial warming properties and is much more potent than carbon dioxide (CO₂).

Although an individual cow has an inconsequentially small carbon footprint, according to the United Nation’s Food and Agriculture Organization (FAO) there are more than 1.4 billion cows in the world.² In fact, the FAO estimates that the livestock industry is responsible for nearly 15% of humanity’s yearly carbon footprint, and cows produce approximately 65% of livestock emissions.³

I won’t go into detail on every aspect of AFOLU, but most components can simply be summarized as soil and nutrient management. However, the biggest section, “Land Use Change and Forestry,” is worth fully dissecting. This block is calculated from a wide number of different land use changes, but you can basically think of it as deforestation. Forests are incredible carbon banks, able to store several tons of carbon in every tree. So, when people remove a section of forest with the slash and burn technique, we are releasing this carbon into the atmosphere.

Most people have already heard that deforestation is bad for the planet, but what does this have to do with food? You might find it disheartening to learn that scientists from REDD, an organization established through the United Nations to protect the Earth’s forests from deforestation and degradation, have named agriculture as the most important driver of global deforestation.⁴

In the 10,000 years since we first began digging in the dirt, we have driven the cultivation of food to an unprecedented scale. Earth’s land surface is approximately 15 billion hectares, of which 4.5 billion are either glaciers or deserts, leaving about 10.5 billion hectares of “habitable land.”⁵ Since 8000 BCE, humans have converted roughly 5 billion hectares of this natural land to agricultural use, and 4 billion hectares of that land was transformed in just the last 300 years. To put it simply, in a very short amount of time we have converted about half of the world’s habitable land from natural ecosystems to agriculture. Changes to the Earth’s surface at this scale have consequences, especially when it comes to climate change. Figures 2 and 3 illustrate just how significantly we have changed the Earth in such a short amount of time.

Figure 2

Figure 3

Unfortunately, food’s role in climate change doesn’t stop at agriculture. AFOLU’s carbon footprint considers the greenhouse gas emissions from agriculture and land use change, but this is only the very first step of the food system. After we have grown our food, it will need to be transported, processed, refrigerated, cooked, and we will need to dispose of any food waste created along the way. The FAO estimates that food waste alone produces 8% of our yearly global carbon emissions.⁶ Every step of our current food system, from agriculture to waste disposal, releases billions of tons of carbon into our atmosphere, making food’s role in global warming one that we cannot afford to ignore.

While there are numerous climate activism campaigns encouraging citizens to turn off the lights, drive less, or install solar panels, food does not receive enough attention in the United States. While some cities and organizations are calling specific attention to the importance of food’s carbon footprint, many Americans have never been introduced to this information. However, projects like Drawdown – “The most comprehensive plan ever proposed to reverse global warming” – have been working to spread information about food systems as one the most important sectors in the fight against climate change. In fact, 8 of Drawdown’s top 20 solutions to reverse global warming are specifically in the food sector, and most of the other 12 indirectly involve food systems.⁷ Even Drawdown’s number one solution to reverse global warming, Refrigerant Management, is primarily a materials problem, but also an integral piece of our modern food system.

For humans to win the fight against climate change, we will need to rethink and rebuild every sector of our society. If we are going to continue to thrive as a species despite the changes that our planet is undergoing, we must give food more attention.

Sources

1. Smith P., M. Bustamante, H. Ahammad, H. Clark, H. Dong, E.A. Elsiddig, H. Haberl, R. Harper, J. House, M. Jafari, O. Masera, C. Mbow, N.H. Ravindranath, C.W. Rice, C. Robledo Abad, A. Romanovskaya, F. Sperling, and F. Tubiello, 2014: Agriculture, Forestry and Other Land Use (AFOLU). In: Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Edenhofer, O., R. Pichs-Madruga, Y. Sokona, E. Farahani, S. Kadner, K. Seyboth, A. Adler, I. Baum, S. Brunner, P. Eickemeier, B. Kriemann, J. Savolainen, S. Schlömer, C. von Stechow, T. Zwickel and J.C. Minx (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA. Retrieved from: https://www.ipcc.ch/pdf/assessment-report/ar5/wg3/ipcc_wg3_ar5_chapter11.pdf
2. Tayyibb, S. (2010). Stastistical Yearbook of the Food And Agricultural Organization for the United Nations. Retrieved from: http://www.fao.org/docrep/017/i3138e/i3138e07.pdf
3. Gerber, P.J., Steinfeld, H., Henderson, B., Mottet, A., Opio, C., Dijkman, J., Falcucci, A. & Tempio, G. 2013. Tackling climate change through livestock – A global assessment of emissions and mitigation opportunities. Food and Agriculture Organization of the United Nations (FAO), Rome. Retrieved from: http://www.fao.org/3/a-i3437e.pdf
4. Kissinger, G., M. Herold, V. De Sy. Drivers of Deforestation and Forest Degradation: A Synthesis Report for REDD+ Policymakers. Lexeme Consulting, Vancouver Canada, August 2012.Retrieved from: https://www.forestcarbonpartnership.org/sites/fcp/files/DriversOfDeforestation.pdf_N_S.pdf
5. Max Roser and Hannah Ritchie (2018) – “Yields and Land Use in Agriculture”. Published online at OurWorldInData.org. Retrieved from: https://ourworldindata.org/yields-and-land-use-in-agriculture
6. Food and Agriculture Organization of the United Nations (FAO). (2011). Food Wastage Footprint & Climate Change. Retrieved from: http://www.fao.org/3/a-bb144e.pdf
7. (2017). Food Sector Summary. Retrieved from: https://www.drawdown.org/solutions/food