It won’t come as much of a surprise that the industrial livestock sector has a major environmental impact. But it’s worth sharing the numbers, just because they’re so staggering: Global livestock production is responsible for 14.5% of human-induced greenhouse gas emissions, according to the FAO, and while it occupies nearly 80% of agricultural land, it provides less than 20% of the world’s calories.
To understand the climate impact of meat, first consider the amount of land that’s required to grow food to then feed to animals. “In many places, there is competition between land use for agriculture and land use for preserving biodiversity and some of our most important forests,” Bergen notes, pointing to regions like the Amazon that show how large-scale animal agriculture can destroy local communities and ecosystems.
Then, you have the emissions of the livestock itself. Ruminant animals (cows, sheep, and goats) are the worst offenders here. They have multiple stomach compartments that break down food through a fermentation process that releases methane–a powerful greenhouse gas that has 25 to 80 times the warming potential of carbon dioxide. “That methane gas is what’s really contributing to their impact,” Rose notes. According to one 2017 analysis, the overall environmental impact of ruminant meat is about 100 times that of plant-based foods. Not to mention, plant-forward diets tend to be healthier than carnivorous ones by most metrics.
Livestock with a so-called “monogastric” (aka, one chamber) stomach design (think chickens and pigs) do not emit methane and therefore tend to be a better pick from a sustainability perspective. But of course, the way an animal is raised also affects its overall impact. Grass-fed meat from a small farm that uses regenerative grazing practices will be a better choice for the environment, animal welfare, and human health than meat raised on a feedlot somewhere. Like every other sustainability conversation, this one is nuanced and it doesn’t have easy answers.