A new 2026 study from the UK published in Royal Society Open Science indicates that organic egg production creates double the climate impact of farming chickens who are confined in small cages. Researchers calculated that converting the entirety of UK egg production to organic free-range systems would result in greenhouse gas emissions reaching 2,316,000 tonnes of CO2 equivalent (tCO2e). In contrast, an entirely caged system would produce 1,184,000 tCO2e (and replacing the entire egg industry with plant-based alternatives would reduce the emissions much further).
The study examined data from UK poultry farms to evaluate environmental consequences including greenhouse gas emissions, land use, and pollution types, alongside welfare measures such as chicken mortality. Organic free-range farming demonstrated the highest chicken mortality and performed worst in land use, acidification, and water eutrophication. The increased environmental impact stems from organic free-range models requiring a higher number of Chickens to yield the identical output of eggs, whereas birds who are imprisoned in cages convert feed more efficiently.
Under current practices, where production is divided between caged, barn-housed, free-range organic, and free-range non-organic systems, total emissions are estimated at 1,439,000 tCO2e. However, the authors acknowledged that the study relied on data from 2009-2010, which does not capture recent developments in production, nor did it examine impacts regarding pesticides or biodiversity.
Dr Harriet Bartlett, senior research associate at Oxford University’s Smith School of Enterprise and the Environment, said to The Guardian, “Meat and dairy get a bit more attention, talking about environmental sustainability, whereas [egg production] hasn’t been as researched… We found an important trade-off… It’s that the types of farms that are generally regarded as being better for animal welfare, like organic and free-range, can actually require more birds to produce the same amount of eggs because they’re less, less efficient and they can have higher environmental impacts… Organic could come out better on pesticide toxicity, maybe biodiversity on farm as well.”
Lee Holdstock, head of regulatory and trade affairs at Soil Association Certification, said, “While intensive systems can have lower emissions per unit of output because birds use feed more efficiently, this reflects only one part of the picture… A truly sustainable food system must also consider impacts on nature, soil health, water quality, the use of synthetic inputs, and animal welfare.”
