Vol. XXXIII · Modern Techniques and the Frontier Plate 9 of 11food and climate, greenhouse gas emissions, carbon footprint, CO2 equivalent, beef, lamb, dairy, poultry, pulses, food miles, food waste, Poore and Nemecek, life-cycle assessment, sustainable dietTF

Food and Climate.

A 150 g beef steak carries about 15 kg of greenhouse gases; the same weight of lentils, about 0.15. Transport is usually a small part of either.

Life-cycle assessments add up everything it takes to produce a food: land use change, fertiliser and manure, methane from cattle digestion and from rice paddies, feed, processing, packaging, transport and retail. The largest study, by Joseph Poore and Thomas Nemecek (2018), pooled data from about 38 000 farms in 119 countries. Its averages per kilogram of product range from about 100 kg of CO₂-equivalent for beef from beef herds and 40 for lamb, through 24 for cheese, 12 for pork and 10 for poultry, to about 1–4 for most plant foods and under 1 for potatoes and peas. Variation within a food is large — the worst beef farms emit many times the best — but the differences between foods are larger still.

Two other findings matter for cooks. Transport is usually a small share — often under a tenth of a food's footprint — except for food flown in by air; what you eat matters far more than where it comes from. And food that is lost or wasted carries all its emissions with it: food loss and waste account for roughly 8–10 % of global emissions (XXXI.10). So the kitchen's levers are the menu — more plant-forward dishes, smaller portions of the highest-emitting foods, using whole animals well — and waste. The workshop builds a plate.

Below: the greenhouse-gas emissions of a plate with the protein and portion you choose and a side of rice, potatoes or bread (mean emissions per kilogram from Poore and Nemecek 2018, as compiled by Our World in Data), against the same plate with each other protein.

What you will learn
Workshop
Mean kg CO₂-equivalent per kg of product (Poore and Nemecek 2018, via Our World in Data): beef 99.5, lamb 39.7, cheese 23.9, farmed fish 13.6, pork 12.3, poultry 9.9, eggs 4.7, tofu 3.2, peas and lentils (peas) 1.0; sides — rice 4.5, wheat (bread) 1.6, potatoes 0.5. Plate = Σ grams ÷ 1000 × factor (exact arithmetic on the averages; real farms vary widely).

The menu is the lever

A 150 g beef portion carries about 15 kg of CO₂-equivalent on these averages; chicken about 1.5; lentils about 0.15 — a factor of about 100 between beef and pulses per kilogram. The side dish matters little beside the protein. These are global averages, and a particular farm can do much better or worse; but no realistic improvement closes the gap between ruminant meat and plants.

In practice: make pulses, grains and vegetables the centre of more dishes (XXIX.5, XX.8), and use meat — especially beef and lamb — as a seasoning or a smaller portion rather than the whole plate; choose poultry, pork, eggs or sustainably farmed fish over ruminant meat more often; use whole animals and their by-products (XXXI.4); cut waste by planning and portioning (XXXI.10, XXIII.1); avoid air-freighted produce, which is the exception where transport counts. Present the change as delicious food, not as sacrifice: the world's great vegetarian cuisines (XXIX.10) show how.

At the stove

Plan a week of dinners and estimate their emissions with the factors in the caption. Swap two beef meals for pulse dishes and compare.

Cattle emit methane from the fermentation in their rumens (enteric fermentation); methane traps far more heat than CO₂ over decades, which, with the land cattle need, is why beef and lamb top every list — beef from dairy herds, which share their emissions with milk, has a lower footprint than beef from beef herds.

Terms

CO₂-equivalent
Greenhouse gases expressed as the CO₂ with the same warming effect.
Life-cycle assessment
Counting emissions from farm to shop.
Enteric methane
Methane from ruminants' digestion.
Plant-forward
Dishes centred on plants, with meat as an accent.
Emissions per kg: beef ~100, lamb ~40, cheese ~24, pork ~12, poultry ~10, eggs ~5, tofu ~3, pulses ~1 kg CO₂e (2018 averages). What you eat matters far more than how far it travelled; waste carries all its emissions.

Sources

  1. J. Poore and T. Nemecek, "Reducing food's environmental impacts through producers and consumers", Science 360 (2018) 987–992; mean greenhouse-gas emissions per kilogram of product as compiled by Our World in Data (kg CO2-equivalent): beef (beef herd) 99.5, lamb 39.7, cheese 23.9, farmed fish 13.6, pork 12.3, poultry 9.9, eggs 4.7, rice 4.5, tofu 3.2, milk 3.2, wheat 1.6, peas 1.0, potatoes 0.5, nuts 0.4.
  2. UNEP, Food Waste Index Report 2024: about 1.05 billion tonnes of food wasted in 2022 — about 60 % in households, 28 % in food service and 12 % in retail — beside the roughly 13 % lost between harvest and retail (FAO); food loss and waste together account for about 8–10 % of global greenhouse-gas emissions.