Dairy milk production is associated with higher greenhouse gas emissions, land use, and water consumption compared to plant-based alternatives like soy milk. This makes plant-based milks a more environmentally friendly option. ⁴

Dairy farming, which involves cattle grazing and feed crop cultivation, requires approximately ten times the land needed for producing plant-based milk alternatives. Additionally, the process of producing cow’s milk is associated with 3 times more  greenhouse gas emissions than plant-based milk. This is largely due to methane, a potent greenhouse gas, which is emitted by cows. Plant-based milks generate about a third of the greenhouse gas emissions compared to cow’s milk.⁵

Furthermore, cow’s milk production is significantly more water-intensive, requiring between two to twenty times more freshwater. This high water demand is linked to the water required for feed crop irrigation and cattle hydration. Lastly, cow’s milk production contributes to higher levels of eutrophication – the excessive richness of nutrients in bodies of water, often due to runoff from the land, which causes a dense growth of plant life and death of animal life from lack of oxygen. This phenomenon is exacerbated by the nutrient-rich waste produced in dairy farming. These environmental impacts highlight the sustainability advantages of plant-based milk alternatives. 

With respect to soy milk, it is important to note that 95% of Brazilian soy is used for animal feed. Globally, more than three-quarters ⁶ of soy, by mass, is used for animal feed. The other main co-product is soybean oil. This means that very little of Amazonian land-use pressures from soy have been driven by crops for direct human consumption; most is for animal feed.

For precise figures and further details, you can refer to studies such as “Reducing food’s environmental impacts through producers and consumers” ^{1, 2}  by J. Poore and T. Nemecek, published in Science which provides a comprehensive analysis of the environmental impacts of various food products, including dairy and plant-based alternatives. Additionally, the report from the Food and Agriculture Organization of the United Nations (FAO)  Livestock’s Long Shadow ⁶  provides extensive data on the environmental impact of livestock farming, including dairy production.