Organic eggs may have a greater climate impact than eggs from chickens in cages, according to new research published in Royal Society Open Science. The study suggests that if the UK's entire egg production shifted to an organic free-range model, greenhouse gas emissions could reach 2,316,000 tonnes of CO2 equivalent (tCO2e).
In contrast, a fully caged system for UK egg production would emit an estimated 1,184,000 tCO2e. The researchers attribute this difference to organic free-range models requiring more chickens to produce the same number of eggs, as caged birds tend to be more efficient.
The study, co-authored by Dr Harriet Bartlett of Oxford University’s Smith School of Enterprise and the Environment, also found that organic free-range production performed worse in terms of potential for water eutrophication, acidification, and land use. Chicken mortality was also highest in organic free-range farming.
However, the research used data from 2009-2010, which the authors noted as a limitation, as it does not include more recent developments in egg production. The study also did not account for other environmental factors such as pesticides or biodiversity.