Dairy farming accounts for 4% of global greenhouse gas emissions, according to a United Nations report.
The study, which covers the global dairy business, was published by the United Nations Food and Agriculture Organisation (FAO).
Samuel Jutzi, director of the FAO’s animal production and health division, said the report covered everything from nomadic herds to milk processing plants.
“This report is fundamental to understand and identify opportunities for reducing the environmental impact of the dairy sector.”
The 4% figure includes emissions associated with the production, processing and transportation of milk products and meat from dairy animals.
Excluding meat production, the sector contributes 2.7% of global emissions.
In 2007, the dairy sector emitted 1.969bn tonnes of CO2 equivalent, of which 1.328bn tonnes were attributed to milk.
Some 151m tonnes of CO2 were attributed to meat from culled dairy animals, and 490m tonnes to calves raised for meat.
The global average of emissions per kilogramme of milk and related milk products is estimated at 2.4kg CO2 equivalent.
Methane contributes most to the global warming impact of milk, accounting for about 52% of emissions.
Nitrous oxide accounts for 27% of emissions in developed countries and 38% in developing countries.
Carbon dioxide accounts for a higher share of emissions in developed countries (21%) than in developing countries (10%).
The assessment is part of an ongoing programme to analyse and recommend options for climate change mitigation.
The next step is to use a similar approach to quantify emissions associated with other major livestock, including poultry, small ruminants and pigs.
A final report will be published in 2011.