A UConn-led study published in the Journal of Dairy Science used five years of farm-level data from the Bangladesh Agricultural University Dairy Farm to recalculate the carbon footprint of milk. Using IPCC Tier 2 methods instead of generalized Tier 1 defaults cut the estimated footprint by 27%, to 5.18 kg per kg of milk. Enteric fermentation made up 48% of on-farm emissions, followed by feed at 24%, manure at 20%, and energy use at 8%. The biggest driver of improvement was productivity. Milk output per cow rose from 3.53 kg per day in 2018 to 5.76 kg in 2023, a 63% gain from genetic selection and better feed management. That helped reduce the carbon footprint by 37% over the study period. The researchers also adjusted for the fact that Bangladeshi cattle are raised for both meat and dairy, so only about half of farm emissions are allocated to milk, compared with roughly 90% on specialized U.S. farms. The study did not include emissions from processing or transporting milk after it left the farm. Still, it shows why farm-specific data matter for carbon accounting and trade decisions.
