Organic free-range eggs have higher carbon footprint than caged eggs, study finds
Organic eggs are twice as harmful to the climate as eggs from caged chickens, according to a new study published in Royal Society Open Science. The research, led by Dr Harriet Bartlett from Oxford University's Smith School of Enterprise and the Environment, found that switching the UK's entire egg production to an organic free-range model would result in greenhouse gas emissions equivalent to 2,316,000 tonnes of CO2 (tCO2e). In contrast, a fully caged system would emit only 1,184,000 tCO2e.
Efficiency drives environmental impact
The main reason for the difference is efficiency. Organic free-range systems require more chickens to produce the same number of eggs because birds in cages are more feed-efficient. The study also found that organic free-range production scored worst in potential for water eutrophication, acidification, and land use. Additionally, chicken mortality was highest in organic free-range farming.
Study limitations and trade-offs
The researchers acknowledged that the study used data from 2009-2010, which may not reflect recent developments in egg production. The research did not account for other environmental impacts such as pesticide use or biodiversity. Dr Bartlett noted, "I'd say perhaps it's also a little bit of a blind spot when we talk about sustainability. Meat and dairy get a bit more attention, talking about environmental sustainability, whereas [egg production] hasn't been as researched."
Welfare vs. environment trade-off
Bartlett explained the key finding: "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 efficient and they can have higher environmental impacts." However, she cautioned that the research does not show the full picture, as organic systems could perform better on pesticide toxicity and on-farm biodiversity.
Industry response
Lee Holdstock, head of regulatory and trade affairs at Soil Association Certification, who was not involved in the study, said the research "highlights some important trade-offs" but gives an "incomplete picture of environmental impact." He added, "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."
Current UK egg production emissions
The researchers estimated that under the current UK regime, where egg production is split between caged, barn-housed, free-range non-organic, and free-range organic systems, emissions amount to 1,439,000 tCO2e. Laying hens are the largest group of animals kept in cages worldwide, and global egg consumption is rising, making their treatment an important welfare consideration.
