The School for Moral AmbitionSeptember 2026

The environmental impacts of food systems

Hannah Ritchie

What will we learn?

Food security and diets

  • State of food security and nutrition
  • The efficiency of our food system

Environmental impacts of food

  • Which foods have the largest impact?
  • What is most effective in reducing these impacts?

Animal welfare

  • Number of animals killed + living conditions of livestock

Food security

  • 800 million don’t get enough food to eat (calories)
  • This share has gone down over time, but progress has stagnated in the last few years
  • Billions can’t afford a complete “healthy” diet

Food security

A chart compares the cost of a healthy diet to median daily incomes across various countries. The vertical axis represents the cost of a healthy diet and median incomes in 2017 international dollars, ranging from $0 to $65. Each bar shows the median income for countries such as the USA, UAE, Germany, and Japan, which are depicted at the higher end of the chart. Lower-income countries, such as India, Nigeria, and Ethiopia, are positioned at the lower end with bars indicating that the cost of a healthy diet is higher than their median incomes. Dashed lines at $11, $18, and $37 indicate income levels based on spending percentages on food. The chart highlights how, in some countries, a healthy diet costs less than median incomes, while in others, it represents a significant financial burden. Data sources include Herforth et al. (2020), and it’s licensed under CC-BY by the author, Hannah Ritchie.

Making food more expensive is not a solution

Hunger is not a problem of global food shortage

Hunger is not a problem of global food shortage

Global-soy-production-to-end-use.png

We have become very good at growing food

Yields are measured in tonnes per hectare. Cereals include wheat, rice, maize, barley, oats, rye, millet, sorghum, buckwheat, and mixed grains.

We use bulk calories and protein very inefficiently

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We use bulk calories and protein very inefficiently

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We use food less efficiently as we get richer

Share of domestic cereal supply allocated to direct human food, rather than animal feed or biofuels. GDP is adjusted for inflation and differences in living costs across countries.

We use food less efficiently as we get richer

Average meat supply per capita, measured in kilograms per year, versus GDP per capita, adjusted for inflation and differences in living costs between countries. Figures do not include fish or seafood.

Environmental impacts of food production

Environmental-impacts-of-agriculture-v2.png
Proportional block diagram of global land use for food production where it shows Earth's surface split into land and ocean, habitable land divided into agriculture, forests and other uses, most agricultural land is devoted to livestock rather than crops, and global calories and protein largely come from plant-based foods. Data sources: Food and Agriculture Organization of the United Nations (FAO) and Poore and Nemecek (2018). License: CC-BY to Our World in Data; authors Hannah Ritchie and Max Roser.
A bar chart illustrating global greenhouse gas emissions from food production. The graphic indicates total global emissions as 52.3 billion tonnes of CO₂-equivalents, with 74% attributed to non-food sources and 26% to food sources. Key categories of food emissions are displayed: - Livestock and fisheries contribute 31%, with specific sources including methane from cattle, manure management, pasture management, and fuel use in fisheries. - Crop production accounts for 27% of emissions. - Land use related to food accounts for 24%, distinguished further into 18% from land use change, 4% from cultivated organic soils, and 2% from savannah burning. - Crops for human food represent 21% and crops for animal feed contribute 6% of food emissions. - Additional supply chain components include retail (3%), packaging (5%), transport (6%), and food processing (4%). Wild fisheries account for 1%. The data source is attributed to Joseph Poore and Thomas Nemecek (2018), published in Science, and licensed under CC-BY by the author Hannah Ritchie (November 2022).
Bar chart of the share of global deforestation attributed to production of different commodities, where beef is the single largest contributor and the chart shows which products drive most forest loss. Beef is about 41 percent, oilseeds about 16 percent, forestry and cereals about 12 percent each, and other products (roots and tubers; vegetables, fruits and nuts; coffee, cocoa and spices; plant-based fibres; pulses; sugar) range from about 5 percent to 1 percent. Source: Singh & Persson (2026), Our World in Data; Licensed CC-BY, author Hannah Ritchie.

Which foods have the highest impact?

Greenhouse gas emissions are measured in kilograms of carbon dioxide-equivalents. This means non-CO₂ gases are weighted by the amount of warming they cause over a 100-year timescale.

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Carbon footprints can vary a lot, but even the lowest-carbon beef is still high carbon

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Land use per kilogram of food product

Land use is measured in meters squared (m²) for one year to produce one kilogram of a given food product.

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Eutrophying emissions per kilogram of food product

Eutrophying emissions represent runoff of excess nutrients into the surrounding environment and waterways, which affect and pollute ecosystems.

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Why do animal-based foods tend to have a higher footprint?

  • Ruminants (cows and lamb) emit methane, a strong short-lived greenhouse gas.
  • Large large land use → emissions from land use and deforestation.
  • Manure emits nitrous oxide (N2O) → a powerful greenhouse gas.
  • Low conversion ratios of feed to meat. All of the emissions associated with producing the feed are allocated to the meat.

What is not effective in reducing these impacts?

A bar chart illustrating global greenhouse gas emissions from food production. The graphic indicates total global emissions as 52.3 billion tonnes of CO₂-equivalents, with 74% attributed to non-food sources and 26% to food sources. Key categories of food emissions are displayed: - Livestock and fisheries contribute 31%, with specific sources including methane from cattle, manure management, pasture management, and fuel use in fisheries. - Crop production accounts for 27% of emissions. - Land use related to food accounts for 24%, distinguished further into 18% from land use change, 4% from cultivated organic soils, and 2% from savannah burning. - Crops for human food represent 21% and crops for animal feed contribute 6% of food emissions. - Additional supply chain components include retail (3%), packaging (5%), transport (6%), and food processing (4%). Wild fisheries account for 1%. The data source is attributed to Joseph Poore and Thomas Nemecek (2018), published in Science, and licensed under CC-BY by the author Hannah Ritchie (November 2022).

What is not effective in reducing these impacts?

Greenhouse gas emissions are measured in kilograms of carbon dioxide-equivalents (CO₂eq) per kilogram of food.

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What is not effective in reducing these impacts?

  • Food miles are less important than many people think.

Transport's share of global greenhouse gas emissions from food

Transport is responsible for 4.8% of global greenhouse gas emissions from the food system. Shown is the breakdown by transport type in 2015.

What is not effective in reducing these impacts?

  • Food miles are less important than many people think.
  • Packaging and processing is also not a major contributor.
  • Organic has mixed results. Yield losses mean using more land.
  • Grass-fed beef has a larger land footprint than grain-fed, and can have a larger carbon footprint.

What is effective in reducing these impacts?

  • Reductions in meat and dairy consumption.
  • Meat swapping (beef → chicken or fish). Beware of trade-offs with animal welfare.
  • Increased productivity (crop yield and “efficient” meat production).
  • Reductions in food waste (supply chain losses and consumer)
Food-emissions-by-reduction-scenario-Clark-et-al.png
Land-use-of-different-diets-Poore-Nemecek.png

Animal welfare

Land animals slaughtered for meat

These numbers do not include additional deaths that happen during the production of meat and dairy, chickens slaughtered in the egg industry, and other land animals for which there is no data.

An infographic titled "Most livestock in the United States are factory-farmed." It lists the percentages and numbers of animals raised in factory farms, defined by the EPA as operations with intensive feeding for over 45 days. Chickens: 99.96%, 9.2 billion; Turkeys: 99.8%, 260 million; Farmed fish: 100%, 530 million; Cows: 75%, 66 million; Egg-laying hens: 98.3%, 380 million; Pigs: 98.6%, 73 million. Data source: Sentience Institute (2024), with data from 2022.

Effective regulation can change things fairly quickly

Share of egg-laying hens in cage-free systems. Cage-free housing systems include barns and free-range (non-organic and organic) farms.

Effective regulation can change things fairly quickly

Butterfly chart showing the number of animals killed to produce one tonne of meat vs. the greenhouse gas emissions of producing that meat. They are inversely correlated.
Image of chickens at different life stages, in the 1950s, 1970s and 2005. Chickens in 2005 are much bigger than those in the 1970s and 1950s.

Overview

Overview

  • Food production has a large environmental impact.
  • This could increase as people get richer and diets shift to more resource-intensive ones.
  • From a human perspective, this is a good thing. You will not be able to stop dietary diversification.

Overview

  • It’s not all doom-and-gloom. We have incredible capabilities to feed 10 billion people.
  • Most of us get good, nutritious food without doing back-breaking work in the fields all day. This is unique.
  • We could have the technologies to do this on a fraction of the land we use today, and with a much smaller carbon and water footprint.

If you want diets to shift, the alternatives need to be…

  • Cheap
  • Nutritious
  • Tasty
  • Easy to substitute
A presentation by Hannah Ritchie
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