How are carbon emissions during food production generated?

When I think of activities that I do regularly that emit carbon (driving, heating a house), eating food is certainly at the top of the list. It’s something I do every day, by necessity, and it’s by far the most frequent kind of shopping I do. Numerous studies have suggested that making dietary changes is one significant way that you can change your personal carbon emissions, but I also wanted to understand more about what the sources of carbon emissions in the food production process are. 

Estimates of the proportion of global greenhouse gas emissions coming from food production range from 1330% depending on the source, and the average American diet is estimated to produce about 4.7 kg CO2 eq per person per day, which comes out to yearly CO2 emissions of just over 2 tons. My carbon emissions are estimated around 16-40 kg/year; so, this is actually not insignificant. (Flight emissions, driving and heating my home are still the biggest three other contributors.) 

So, what drives emissions in food production? The sources of the most carbon emissions surprised me a bit; I was expecting that machinery used on farms or transportation of food to be the main drivers of emissions. Instead, release of methane gas from livestock and nitrous oxide gas emitted from fertilizers are the most significant generators of greenhouse gases, representing 65% of emissions. Additionally, land use changes (ie. forests being cut down to turn into crop land) is another significant contributor, making up nearly half of the emissions from farming. Additional sources of emissions come from equipment used at the farms for maintaining fields and harvesting food, but these are actually relatively small contributors to overall emissions. 

One frequently cited heuristic of food consumption is that you should try to minimize “food miles” in your diet, and focus on eating food that is grown close to where you live. Interestingly, though, the Food Climate Research Network (which is an amazing resource about the environmental impact of food production) suggests that food miles may not necessarily tell the whole story. The mode of transportation and growing conditions for a food item have an enormous impact on that product’s carbon emissions. For example, if you live in Sweden, the emissions from a tomato grown locally in a greenhouse may actually be larger than a tomato grown in Spain and transported by train. Since most of the time we lack completely insight into the production and transportation conditions of everything we buy, it is very difficult to assess the carbon impact of buying a particular kind of food. 

In some ways, I actually found this to be a relief. Shopping for food at a local farmer’s market is not something that is feasible for me to do every week, all year. I think there’s lots of good reasons besides just carbon emissions to do this if you can afford it and have time, but it was nice to learn that it’s not necessarily going to guarantee a major reduction in carbon emissions to do so. BUT, this also points to the importance of policies in shaping consumer behavior; it’s not feasible to ask consumers to modify their actions without giving them transparent and actionable information about the impact of their choices. In the case of carbon emissions, the most straightforward way to do this is by applying a carbon tax that reflects the total carbon footprint of anything you buy. If the more-carbon intensive products cost more, it’ll be much easier for you to modify your behavior, without needing to research every nitty gritty detail of their production. 

Which brings us to the question: if you are going to change your behavior, what are the most impactful ways to change your diet? There are two major things that you have control over and can optimize for:

  1. Eat less meat

I’ve discussed this before on the blog, and lots has been written about this topic; but, decreasing your meat consumption, especially of red meat, is the single most impactful change you can make in your diet. Studies have estimated that going vegan could reduce emissions by up to 60% and being vegetarian by 50%. And even if you have reasons to not be completely vegetarian, simply shifting from eating red meat to poultry can also have a significant impact. 

2. Waste less food

It’s estimated that up to 24% of food that is produced is thrown away. That’s a huge amount of carbon emissions for nothing. Anything you can do to reduce your own personal food waste is a win. Buy only what you need, and if you’re able to, compost anything you absolutely have to throw away. I love a site called Saymmm for reducing food waste; it’s a meal planning site that lets you put in recipes and make shopping lists. It will take a recipe, parse the ingredients, and then make a unified shopping list organized by area of the store. It’s a tool we use to make sure we’re only buying the ingredients we need for recipes we’ll actually cook. 

It’s been unusual in my research that the answer to my consumerist questions are simpler than I expect- I’m happy to have learned more details of what factors cause carbon emissions in food production, and that there are two key elements that I have some control over. I’ll be continuing to make mostly vegetarian choices with this extra information in mind!!

P.S. As I mentioned, Foodsource is an amazing resource. They’re based in the UK, so many of their examples are European-centric, but I’ve a lot from their resources. I especially leaned on this chapter on Food Systems and Greenhouse Gas Emissions and this one on What is a healthy sustainable eating pattern? for this post- I highly recommend their other resources as well!

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