The Carbon Footprint Of Dairy Cows

Concern about the effects of climate change has long been driving a demand for research focused on the causes of human-made carbon emissions. It is well-established that industrial agriculture is one of the most significant sources of climate change; the Faunalytics library contains many articles on this very subject.

When considering the most damaging aspects of agriculture, many of us point first to large-scale animal production and, especially, cattle farming. Moreover, we often focus on the negative environmental impact of beef production but ignore dairy. Yet in Australia, farms centered primarily in the southern regions of the nation produce most of the country’s dairy supply—9 billion tons per year; the country imports less than 200,000 tons of dairy annually.

Researchers in Australia, in partnership with the country’s dairy industry, developed a method to measure the carbon footprint of Australian dairy farms. The resulting report brings together details about dairy farms’ carbon emission contribution on a national scale, focusing on the environmental impact of feed production, fertilizer use, methane (from cow manure), and land use. Key aspects of the study included the following:

• Feed Production. Fifty-seven percent (57%) of Australian dairy farms sampled in this study use feed from pasture as opposed to from feedlots. (Notably, the authors assumed that feed sources originated in Australia, expect for soy and palm kernel which come from Brazil and Malaysia.)
• Fertilizer Use. The study included the effects of leaching, runoff, and the atmospheric deposition of nitrogen produced by fertilizers. Ninety percent (90%) of the farms in the study use mineral fertilizers and soil conditioners; only 15% use organic fertilizers, which were considered waste products and not included in the measurements.
• Methane. A dairy cow produces an average of 1,530 kg of manure every year, which emits the greenhouse gas methane. (An average human produces about 130 kg of fecal waste per year.) Thus, if not managed properly, manure and the methane gas it emits can lead to high levels of environmental degradation.
• Land use. Agricultural land use by the dairy industry did not increase significantly from 1990 to the time of the study. As such, these measurements had almost no impact on the total emission calculations. However, energy and water usage was included in the land use measurements.

The average carbon footprint of Australian milk was found to be 1.11 kg of CO₂ for each kilogram of fat-and-protein-corrected-milk—more than a 1:1 ratio. Importantly, the researchers also found that 89.8% of the greenhouse gas emissions from farms could be attributed to milk production but only 10.2% to meat production.

This is one of the first nationwide studies in Australia that assesses dairy farms’ contribution to the nation’s overall carbon emissions. While similar reviews exist in the literature, their criteria for and measurement of emissions varies; therefore, comparing their results is misleading because differences are likely due to inconsistent measurement techniques rather than to variations in actual emissions. Developing standard methods to measure carbon emissions across a single industry, as the authors of this study have done, is necessary to make reasonable comparisons.

For animal advocates, this study shows that dairy cannot be ignored as a source of significant carbon emissions. Furthermore, we might consider shifting some of the emphasis on the negative environmental impacts of meat production to that of dairy and all animal production.