This table is based on research done by Oxford scholars Poore and Nemecek, in a study called 'Reducing food's environmental impacts through producers and consumers' published in 2018. The study found that cows milk contributed 3.2 kgs of carbon dioxide, followed closely by rice milk, which contributed 1.2 kgs. With soy milk contributing 1 kg, oat milk 0.9 kg, and almond milk 0.7 kg, this makes it the least harmful of all the milks as far as greenhouse gas emissions are concerned. Researchers found cows milk produced the highest amount of carbon/greenhouse gas emissions.