Understanding the Carbon Footprint of Food Ingredients

Have you ever wondered about the carbon footprint of different food items, such as beef versus chicken? Gaining insight into the greenhouse gas emissions associated with various food groups can guide us toward more sustainable dietary choices.

How Are Carbon Emissions of Food Measured? An Introduction to Life Cycle Assessment (LCA)

Calculating the greenhouse gas emissions of food is a rigorous, science-based process conducted through LCA or Life Cycle Assessment. This method meticulously tracks the carbon footprint of ingredients from production to the point of sale, commonly referred to as "farm to industry gate." The impact is measured in kilograms of carbon dioxide equivalents (kg CO₂e), encompassing various greenhouse gases, including carbon dioxide, methane, and nitrous oxide.

While the term "carbon emissions" is widely used, it is scientifically imprecise, as food production involves emissions of gases beyond carbon dioxide. Nevertheless, for simplicity, we will use "carbon emissions" in this discussion.

This analysis aims to provide a general understanding of the carbon emissions associated with basic food components. For a more in-depth exploration, including strategies to substitute high-emission ingredients with lower-emission alternatives, please refer to expert cheat sheet for food professionals in which we discover how to substitute ingredients with ones that have lower emissions to achieve a more cost-efficient and eco-conscious way of preparing dishes.

1. TThe Carbon Emissions of Protein Sources

Values are extracted from the Klimato database which contains data from peer-reviewed papers, conference proceedings, and open source databases.

It's well-known that meat has a higher carbon footprint compared to other food components. Red meat, particularly from ruminant animals like cows, sheep, and goats, has a carbon footprint of approximately 35 kg CO₂e per kilogram. This high level is due to methane production during digestion.

In contrast, poultry and pork have lower carbon footprints, averaging 5.98 kg CO₂e/kg and 7.07 kg CO₂e/kg, respectively. Even more sustainable are plant-based proteins such as lentils, beans, peas, and tofu, which have carbon footprints roughly 5% that of beef.

2. The Carbon Emissions of Dairy Products

Values are extracted from the Klimato database which contains data from peer-reviewed papers, conference proceedings, and open source databases.

Among dairy products, butter is the highest emitter, with a footprint of 10.77 kg CO₂e/kg. This is due to the large quantities of raw milk required for its production—10 to 20 times more than what's needed for milk and 4 to 5 times more than for cheese. A more climate-friendly alternative to butter is vegetable oil, averaging an impact of 3.66 kg CO₂e/kg, about one-third that of butter.

Cheese also has a significant carbon footprint, averaging around 8 kg CO₂e/kg. Plant-based alternatives, such as nutritional yeast, offer lower-emission options, emitting approximately 32% less than traditional cheese.

3. The Carbon Emissions of Seafood

Trawling for shellfish is a fuel-intensive method that damages the sea floor and often results in bycatch, adding to the carbon footprint. Farmed fish have their own emission hotspots, primarily from feed production and farm energy use. To minimize impact, choosing fish that swim closer to the surface, thereby avoiding seafloor damage, is advisable. Notably, mussels have a relatively low carbon footprint, around 0.08 kg CO₂e/kg.

Here are examples of seafood with varying carbon footprints:

• Low Impact: Mussels, sardines
• Moderate Impact: Tilapia, catfish
• High Impact: Lobster, shrimp

Understanding the carbon emissions associated with different food components empowers consumers and food professionals to make more sustainable choices, ultimately contributing to environmental conservation efforts.

4. The Carbon Footprint of Carbohydrates: Which Options Are More Sustainable?

Values are extracted from the Klimato database which contains data from peer-reviewed papers, conference proceedings, and open source databases.

Carbohydrates play a fundamental role in our diets, but their environmental impact varies significantly. The carbon footprint of staple carbs like rice, potatoes, and pasta depends on farming methods, processing, and methane emissions.

Rice: The High-Emission Carbohydrate

Rice has a high carbon footprint of about 3.7 kg CO₂e per kilogram, primarily due to methane emissions from paddy fields. Rice cultivation is responsible for 10-13% of global methane emissions, a potent greenhouse gas that traps heat 25 times more effectively than CO₂. The presence of methanotrophic soil microorganisms in flooded fields significantly increases these emissions, making rice one of the least climate-friendly carbohydrate choices.

Pasta: A Lower-Impact Alternative

Pasta has an average carbon footprint of 1.54 kg CO₂e/kg, making it a more sustainable option than rice. Although pasta undergoes industrial processing, wheat cultivation emits relatively low methane levels. In fact, wheat milling and pasta manufacturing contribute only 20% of its total carbon footprint.

Potatoes: The Most Climate-Friendly Carb

Potatoes are not only nutrient-rich but also one of the most sustainable carbohydrate sources, with a low carbon footprint of just 0.22 kg CO₂e/kg. Their high yield and relatively low fertilizer requirements contribute to their environmental efficiency. However, global potato consumption has shifted from fresh potatoes to processed products like pasta, reducing its dietary prominence.

5. The Carbon Footprint of Fruits & Vegetables: Does Farming Method Matter?

Fruits and vegetables generally have a lower carbon footprint compared to animal-based products. However, their environmental impact varies depending on farming methods, seasonality, and transportation.

Open Field vs. Greenhouse Cultivation

The most significant difference in carbon emissions comes from how fruits and vegetables are grown:

• Open-field cultivation: 0.5 kg CO₂e/kg
• Heated greenhouse cultivation: 2.81 kg CO₂e/kg

Heated greenhouses require intensive energy use for temperature control, lighting, and artificial irrigation, increasing their carbon footprint by nearly six times compared to open-field farming.

Seasonal and Local Choices: The Best Strategy

The best way to minimize emissions is to choose local, in-season produce whenever possible. If local options are unavailable, opt for produce grown abroad in open fields rather than greenhouse-grown local alternatives. For instance, choosing Spanish-grown tomatoes in March is more sustainable than UK-grown tomatoes from heated greenhouses.

The Role of Transportation in Emissions

Transportation contributes only about 5% of the total carbon footprint of most food products (excluding air-freighted produce). This means that the farming method has a much greater impact than transport when determining a food item's overall sustainability.

Key Takeaways: How to Make Climate-Smart Food Choices

1. Meat and dairy have the highest carbon emissions. Swapping red meat for chicken, legumes, or tofu is a more climate-friendly option.
   
   
2. Not all seafood is equal—prioritize fish that swim closer to the surface (like pollock, herring, and mackerel) instead of deep-sea species like cod.
   
   
3. Carbohydrates matter! Rice has a high carbon footprint due to methane emissions, so pasta and potatoes are better alternatives.
   
   
4. Fruits and vegetables vary in sustainability. Always choose seasonal and locally grown produce when possible. If out of season, select open-field produce grown abroad rather than local greenhouse-grown options.

By making small changes to our food choices, we can significantly reduce our carbon footprint and contribute to a more sustainable food system.

Sources

1. Poore et al., 2018
2. Djekic et al., 2014
3. Agribalyse 3.1 (ADEME, 2022)
4. Klimato Carbon Footprint Database
5. Bronson et al., 1997
6. Bevilacqua et al., 2013
7. Clune et al., 2017
8. Neira et al., 2018
9. Denny et al., 2012
10. Crippa et al., 2017