The cow’s amazing ability to sustain itself by eating nothing but grass is one of the marvels of nature, but it comes at a cost.
As grass ferments in the rumen — one of four compartments in the animal’s stomach — it naturally produces methane, a greenhouse gas 28 times more potent than CO2, although shorter lived in the atmosphere. That methane is released through belching and farting, and on average, a single cow can produce about 200 pounds of it per year. The gas is also released by manure, and livestock accounts for about a third of human-related methane emissions, which are collectively responsible for about 30% of global warming.