What's animal farming got to do with biodiversity loss?
Short answer: It's the single biggest driver. Livestock takes 77% of farmland, agriculture causes ~90% of deforestation, and farmed animals now outweigh all wild mammals many times over.
Humans and our livestock make up about 96% of all mammal biomass. Every wild mammal, every elephant, whale, deer, mouse, shares the remaining sliver.
Bar-On, Phillips & Milo (2018), PNAS
The objection
“Climate I get, but biodiversity? That’s about poaching and palm oil and habitat, not whether I eat a burger.”
The answer
It’s almost entirely about the burger. Agricultural expansion is the leading driver of biodiversity loss on land, and the UN’s IPBES global assessment names land-use change as the biggest single cause of decline since 1970 [3]. The thing eating the habitat is overwhelmingly farming, and most farming is livestock.
The land maths is brutal. Animal agriculture uses around 77% of the world’s farmland while providing only 18% of our calories [2]. Roughly 90% of recent global deforestation is driven by agriculture [2][3], with forests, wetlands and grasslands flattened into pasture and feed-crop monocultures that hold a fraction of the wildlife they replaced.
The single figure that reframes everything comes from a 2018 PNAS census of life on Earth: humans and our livestock now make up around 96% of all mammal biomass. Every wild mammal alive, every elephant, deer, fox and whale, shares the remaining 4% [1]. We haven’t just crowded wild animals out. We have replaced them, by weight, with animals bred to be eaten.
Biodiversity loss and diet are the same file. The forests cleared, the species squeezed into that 4%, the monocultures stretching to the horizon: that is what the demand for meat and dairy looks like written across a map.
The fastest way an individual hands land back to wild things is to stop funding the system that took it.