The global food system accounts for 26% of greenhouse gas emissions worldwide (Our World in Data, Poore and Nemecek, 2018). It's not just factories or cars: what we eat every day contributes massively to climate change. But not all foods have the same impact: the difference between a beef steak and a plate of lentils in terms of CO2 emissions is roughly 50-fold. Understanding the carbon footprint of food is the first step toward making dietary choices that have a real impact on the planet.

How to Measure a Food's Carbon Footprint

A food's carbon footprint (measured in kg of CO2 equivalent per kg of product) is calculated through life cycle assessment (LCA): it includes all emissions from production (land use, fertilizers, animal feed, water, energy), processing (industrial processing, refrigeration), transport and distribution, consumption, and waste. The Poore and Nemecek study (Science, 2018)—the largest analysis ever conducted across 40,000 farms in 119 countries—provided the most comprehensive data available. The key finding: variability within the same food category is enormous (one kg of beef can range from 9 to 105 kg CO2eq depending on production system), but animal product categories are systematically far more emissions-intensive than plant-based ones.

Reference Values: Food Rankings by Emissions

Average emissions per 100g of protein (source: Poore and Nemecek, 2018, kgCO2eq): Beef from pasture-raised cattle on deforested land: over 100 kg CO2eq. Beef from intensive farming: approximately 50 kg CO2eq. Lamb and goat: approximately 20 kg CO2eq. Dairy products (cheese): approximately 11 kg CO2eq per 100g of product. Pork: approximately 7 kg CO2eq per 100g. Poultry (chicken, turkey): approximately 6 kg CO2eq. Eggs: approximately 4.5 kg CO2eq. Wild fish (variable): 2 to 25 kg CO2eq (highly variable by species and fishing method). Farmed fish: approximately 3-8 kg CO2eq. Tofu: approximately 2 kg CO2eq. Legumes (chickpeas, lentils, beans): approximately 0.9 kg CO2eq. Nuts and oilseeds: approximately 2.3 kg CO2eq. Wheat and cereals: approximately 1.5 kg CO2eq. Vegetables and fruit (average): approximately 0.3-0.8 kg CO2eq.

Carbon in Food: The Three Main Factors

Food's carbon emissions come primarily from three sources. Land use: forests cleared to create pastures or soybean fields for animal feed release enormous amounts of CO2 stored for centuries. Brazilian beef from deforested areas has an extremely high carbon footprint almost solely for this reason. Enteric fermentation: cattle and sheep produce methane (CH4) during digestion. Methane has a climate-warming potential 28 times greater than CO2 over 100 years. This single source accounts for roughly 14% of the food sector's global emissions. Energy production: synthetic fertilizers (produced through energy-intensive processes), farm machinery, greenhouse heating, and refrigeration throughout the supply chain.

How to Calculate Your Diet's Carbon Footprint

The website myclimate.org and the Giki Badges app (in English) allow you to estimate your annual diet's carbon footprint. In Italian, the ecological footprint calculator from the Foundation for Sustainable Development includes diet as a component. A quick estimate: an average Italian omnivorous diet produces roughly 2.5-3 tonnes of CO2eq per year from food alone. A vegetarian diet: approximately 1.5 tonnes. A vegan diet: approximately 1 tonne. Switching from beef to chicken as your primary meat reduces food emissions by 30-40%. Switching from meat to legumes as your primary protein source reduces emissions by 60-70%.

The Five Food Swaps with the Greatest Climate Impact

1. Beef → legumes or tofu as your primary protein source (reduction of 15-20 kg CO2eq per meal). 2. Cow's milk → oat milk (cow's milk production emits 3 times more CO2 than oats). 3. Lamb → chicken or small fish (mackerel, sardines: extremely low carbon footprint). 4. Aged cheese in large quantities → dried legumes (1 kg of parmesan ≈ 11 kg CO2eq, 1 kg of lentils ≈ 0.9 kg CO2eq). 5. Processed pork (cured meats, sausages) → eggs (industrial processed meat production has a very high footprint due to transformation processes). None of these swaps requires a vegan diet: they simply require redistributing consumption frequency.

How to Read Carbon Labels on Food

Some European countries (France leading the way, followed by Sweden and Germany) are piloting mandatory carbon footprint labeling on food. The Eco-Score system (adopted by some French and Belgian supermarkets) rates the overall environmental impact of foods from A (minimal impact) to E (maximum impact), considering emissions, land use, biodiversity, and water resources. In Italy, this system isn't yet mandatory, but some retail chains are adopting it voluntarily. As consumers: look for Eco-Score or equivalent systems on packaging; prioritize products rated A or B for high-impact categories.

The Local Food Paradox: When Zero-Kilometer Doesn't Cut It

A common assumption is that local food always has a lower carbon footprint than food imported from far away (because it travels fewer kilometers). This intuition is often wrong: transport accounts for only 10-12% of a food's total emissions, while the production system determines 70-80%. A tomato grown in a heated greenhouse in Trento can have a carbon footprint 10 times higher than a tomato grown in open fields in Sicily and transported north. Seasonality (food grown in its natural season, in open fields) is far more important than geographic location for reducing your diet's carbon footprint.