Protein Swap Comparison
Protein is the argument people reach for most often, so it is worth comparing sources on a like-for-like basis: emissions per 100 grams of protein delivered, not per kilogram of raw product. The figures below come from the Poore & Nemecek (2018) global meta-analysis covering roughly 38,700 farms in 119 countries.
Short answer: Per 100 g of protein, beef averages about 50 kg CO2-equivalent while tofu averages about 2 kg and pulses about 0.8 kg — a difference of roughly 25 to 60 times.
2595kg CO₂e
Beef (beef herd), per year
42kg CO₂e
Peas, beans & lentils, per year
2553kg saved
62.4× lower
| Source | kg CO₂e / 100 g protein | Relative |
|---|---|---|
| Beef (beef herd) | 49.9 | |
| Lamb & mutton | 19.9 | |
| Cheese | 10.8 | |
| Pork | 7.6 | |
| Farmed fish | 6.0 | |
| Poultry | 5.7 | |
| Eggs | 4.2 | |
| Milk | 3.2 | |
| Grains | 2.7 | |
| Tofu | 2.0 | |
| Peas, beans & lentils | 0.8 | |
| Nuts | 0.3 |
Global means · Poore & Nemecek 2018
How this is calculated
- Emissions are global mean values per 100 g of protein, cradle to retail, from Poore & Nemecek (2018).
- A serving is treated as 20 g of protein.
- Means hide wide production spreads; the best and worst producers of the same food can differ by an order of magnitude.
Frequently asked
- Which protein source has the lowest carbon footprint?
- Pulses — beans, lentils and peas — are the lowest at roughly 0.8 kg CO2-equivalent per 100 g of protein, followed by nuts and tofu.
- Is chicken a good climate choice?
- Chicken is far lower than beef or lamb, at about 5.7 kg CO2e per 100 g protein, but still several times higher than tofu or pulses, and it involves the most individual animals per kilogram.
- Do plant proteins provide all essential amino acids?
- Yes. A varied plant diet supplies all nine essential amino acids across the day; soy, quinoa and buckwheat each supply them in a single food.