The figures come from two of the most carefully constructed peer-reviewed datasets in environmental science. The water footprint estimate is from Mesfin Mekonnen and Arjen Hoekstra of the University of Twente in the Netherlands, who published their global analysis in the peer-reviewed journal Ecosystems in 2012. The carbon footprint estimate is from Joseph Poore at the University of Oxford and Thomas Nemecek at Agroscope in Switzerland, who published their global meta-analysis in Science in 2018. The two studies together represent the strongest available scientific evidence on the environmental cost of beef production.
The Mekonnen and Hoekstra study analysed water-use data from beef production systems across more than a hundred countries, separating the water footprint into three categories. Green water is rainfall used by the plants that feed the cattle. Blue water is irrigation, drinking water, and water used in processing. Grey water is the water required to dilute the pollution produced by the farming operation to acceptable concentrations. The 15,400 litre global average is the sum of all three, with green water accounting for approximately 94 per cent of the total.
The Poore and Nemecek study analysed life-cycle assessment data from 38,700 farms across 119 countries, the largest meta-analysis of food production environmental impact ever conducted. The 99 kilogram carbon footprint figure is the global average for beef produced from dedicated beef herds, in which cattle are raised specifically for meat. Beef from dairy herds, where cows are first used for milk production and later slaughtered for meat, has a smaller carbon footprint of approximately 33 kilograms of carbon dioxide equivalent per kilogram of meat. The average across all global beef production, weighted by source, is approximately 60 kilograms of carbon dioxide equivalent per kilogram. Most of the beef sold in the United States comes from dedicated beef herds.
What 15,400 litres actually means
The water cost of beef is concentrated almost entirely in the feed the cattle eat. Approximately 99 per cent of the water footprint of beef is attributable to the cultivation of the corn, soy, hay, alfalfa, and grass that the cattle consume across their lifetimes. Less than one per cent is the water the cattle themselves drink or the water used in processing the meat after slaughter.
The 15,400 litre figure is a global average. The range across production systems is enormous. Beef from industrial feedlot systems in the United States and Argentina can be produced with as little as 3,000 litres of water per kilogram, because the cattle reach slaughter weight faster and are fed grain rather than range-grazed. Beef from grazing systems in arid regions, particularly in parts of India and sub-Saharan Africa, can require up to 26,000 litres per kilogram, because the cattle take longer to mature and the feed crops have lower water-use efficiency.
Despite this variation, beef is consistently the most water-intensive major food product on Earth. The Mekonnen and Hoekstra data shows the water footprint of beef is approximately 1.5 times that of lamb, 2.5 times that of pork, 3.5 times that of chicken, and 15 times the water footprint of common cereal grains per kilogram of edible product.
What the carbon figures actually mean
The carbon footprint of beef has three main components. The first is enteric fermentation, the digestive process in cattle stomachs that produces methane. Cattle release methane through their breath and through their digestive tracts. Methane is, on a hundred-year timescale, approximately thirty times more potent as a greenhouse gas than carbon dioxide. The methane produced by global cattle digestion accounts for approximately one third of the carbon footprint of beef.
The second component is land-use change. The cultivation of feed crops, the clearing of forest for grazing land, and the conversion of native ecosystems to pasture each release the carbon previously stored in trees, soil, and vegetation. The Poore and Nemecek analysis identified land-use change as the largest single component of beef’s climate impact, accounting for approximately 40 per cent of the total emissions.
The third component is the cluster of farm-level activities that produce emissions across the rest of the production cycle. These include the manufacture and application of fertilisers, the operation of farm machinery, the production of pesticides, the transportation of feed and animals, the slaughtering and processing, and the refrigeration and distribution of the meat. These contribute approximately 30 per cent of the total emissions.
The relative magnitudes matter for understanding what changes in the food system could reduce the impact. Reducing fertiliser use or improving feed efficiency addresses the third component but leaves the first two largely untouched. Eliminating land-use change for new cattle production would substantially reduce the second component but not the first. Reducing global beef consumption is, on the published evidence, the single intervention that would reduce all three simultaneously.
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The American scale
Americans consume more beef per person than the citizens of any other major country in the world, with the United States Department of Agriculture’s Economic Research Service reporting that per capita American beef consumption in 2024 was approximately 58 pounds, or 26 kilograms, per person. Total United States beef consumption in 2024 was approximately 12 million tonnes, the largest national beef consumption figure of any country in the world.
The aggregate environmental footprint of that consumption, applying the global-average per-kilogram figures from the peer-reviewed literature, is substantial. The water required to produce 12 million tonnes of beef at the global average water footprint is approximately 185 trillion litres per year. The carbon dioxide equivalent emissions, using the 60 kilogram per kilogram weighted average for global beef production, are approximately 720 million tonnes per year. Both figures are necessarily approximate because American beef production systems vary in their efficiency, and the aggregate national figures depend on the mix of beef-herd and dairy-herd sources, the degree of feedlot finishing, and other production specifics.
For comparison, the total territorial greenhouse gas emissions of the United Kingdom in 2024 were 373 million tonnes of carbon dioxide equivalent, on the published figures from the UK Department for Energy Security and Net Zero. The carbon footprint of American beef consumption alone is, on the global-average per-kilogram figures, approximately twice the entire annual emissions of the United Kingdom.
The honest limitations of the evidence
Several methodological caveats apply to the figures above.
The water footprint methodology used by Mekonnen and Hoekstra has been contested by some industry researchers. The main critique is that the inclusion of green water, which is rainwater that would have fallen on the land regardless of whether it was used for beef production, overstates the actual water cost of beef. Excluding green water would reduce the figure to approximately 925 litres per kilogram, which is the blue and grey water footprint only. The Mekonnen and Hoekstra response is that the choice of how to use rainwater is itself an environmental decision with consequences for water-stressed ecosystems, and that excluding it underestimates the true opportunity cost. The peer-reviewed debate is ongoing.
The carbon footprint figures depend on the global warming potential metric used to convert methane and nitrous oxide into carbon dioxide equivalent. The Poore and Nemecek study uses the 100-year global warming potential framework. On a 20-year framework, which more accurately represents the immediate climate impact of methane, the beef carbon footprint figures would be substantially higher. On a 500-year framework, they would be lower. The choice of timeframe is a value judgment about which temporal effects of climate change matter most.
The aggregate figures also do not account for offsetting benefits some beef production systems can provide, including the maintenance of grassland ecosystems, soil carbon sequestration in well-managed pasture, and the use of marginal land that is not suitable for crop production. Carefully managed regenerative grazing systems have, in some peer-reviewed analyses, been shown to be carbon-negative on net. These represent a small share of global beef production but a growing one.
What it means
Several things follow from the differentiated picture of beef’s environmental cost that are worth saying clearly.
The first is that beef is, by every major peer-reviewed metric, the most environmentally intensive widely consumed food on Earth. Lamb is comparable in some metrics but consumed at much lower volume. Pork, chicken, eggs, and farmed fish are all substantially less intensive across water, land, emissions, and biodiversity impacts. Plant-based protein sources are typically one to two orders of magnitude less intensive than beef on the same metrics.
The second is that the variation within beef production is large enough to matter. The difference between the lowest-impact beef production systems and the highest-impact ones is approximately a factor of fifty. Beef produced from dairy herd cattle, in well-managed feedlot systems, with feed grown on rainfed land, has a substantially lower environmental footprint than beef produced from dedicated beef herds raised on land cleared from tropical forest. Both are sold as beef.
The third is that the aggregate American beef footprint, given American consumption levels, is a significant component of the country’s environmental impact. Reducing American beef consumption by even modest amounts would, on the published per-kilogram figures, produce substantial reductions in national water use and greenhouse gas emissions. Switching from beef to chicken, which is consumed at higher per-capita levels in the United States, would reduce the carbon footprint of the same protein intake by approximately 90 per cent.
On the strongest current reading of the peer-reviewed evidence, the environmental cost of American beef consumption is not small, is not in dispute among the major peer-reviewed datasets, and is substantially within the control of the people who decide what to eat.
Whether the cost is worth paying, given the place of beef in American food culture, food security, agricultural employment, and personal preference, is a separate question that the peer-reviewed evidence cannot answer.
The cost itself is what the evidence has now established.
