We often think that our world is an infinite realm comprising great plains, jungles and oceans, teeming with wild animals featured in memorable nature shows like the BBC’s Planet Earth. But the first global census of wild mammal biomass, conducted by Weizmann Institute of Science researchers and reported today in PNAS, reveals the extent to which our natural world—along with its most iconic animals—is a vanishing one.
The new report shows that the biomass of wild mammals on land and at sea is dwarfed by the combined weight of cattle, pigs, sheep and other domesticated mammals. A team headed by Prof. Ron Milo found that the biomass of livestock has reached about 630 million tons—30 times the weight of all wild terrestrial mammals (approximately 20 million tons) and 15 times that of wild marine mammals (40 million tons).
An earlier, widely-discussed study in Nature by researchers in Milo’s lab in Weizmann’s Plant and Environmental Sciences Department showed that in 2020, the mass of human-made objects—anything from skyscrapers to newspapers—had surpassed the planet’s entire biomass, from redwood trees to honeybees. In the latest study, the researchers offer a new perspective on humanity’s rapidly increasing impact on our planet, seen in the ratio between humans and domesticated mammals, and wild mammals.
Comments are closed.