Organic eggs have worse climate impact than eggs from caged chickens
Research finds organic free-range eggs generate nearly twice the greenhouse gas emissions of eggs from caged hens, because more birds are needed to produce the same quantity of eggs.
Organic eggs are twice as harmful to the climate as eggs from chickens kept in cages, according to a new study. If the UK's entire egg production switched to an organic free-range model, greenhouse gas emissions would reach an estimated 2,316,000 tonnes of CO2 equivalent (tCO2e), while a fully caged system would emit 1,184,000 tCO2e.
The study, published in Royal Society Open Science, was conducted by researchers at the University of Oxford. They analyzed data from UK poultry farms to calculate environmental impacts, including greenhouse gas emissions, land use, and pollution types. Also studied were welfare indicators such as mortality rates and the number of hens required to produce a given number of eggs.
The researchers found that organic free-range farming requires more chickens because the birds are less efficient, leading to higher emissions. Mortality was also highest in organic free-range systems. However, the study used data from 2009–2010, which the authors acknowledged as a limitation, as it does not capture more recent developments. The research also did not account for other environmental factors like pesticides or biodiversity.
Lead author Dr. Harriet Bartlett highlighted an important trade-off: farming systems generally considered better for animal welfare, such as organic and free-range, can actually require more birds to produce the same amount of eggs and therefore have higher environmental impacts.
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 stressed that a truly sustainable food system must also consider impacts on nature, soil health, water quality, synthetic inputs, and animal welfare.
The researchers estimated that under the current regime, where egg production is split between caged, barn-housed, free-range non-organic and free-range organic systems, emissions amount to around 1,439,000 tCO2e.
