In the first study of its kind, researchers have measured the mass of all living organisms on Earth. They found that humans only make up about one ten-thousandth of life on the planet in terms of biomass.
The comprehensive analysis was focused on carbon content, which does not account for the water masses of organisms. The results indicate that the total global biomass is around 550 gigatons of carbon (Gt C).
Study lead author Ron Milo is a biologist at the Weizmann Institute of Science in Israel. He explained that while the estimates are not exact, they give a sense of proportion.
According to the research, plants add up to more than 80 percent of the world’s biomass, outweighing humans by 7,500 to one. Nearly 13 percent of the world’s biomass is made up by bacteria, while fungi account for about two percent.
The researchers also discovered that wild mammals are 10 times less prevalent than humans. Overall, humans have cut the number of wild animals by 85 percent.
Livestock such as cattle and pigs, on the other hand, are much more prevalent. In addition, poultry such as chicken and turkeys are three times as abundant as wild birds.
“When I do a puzzle with my daughters, there is usually an elephant next to a giraffe next to a rhino,” Milo told The Guardian. “But if I was trying to give them a more realistic sense of the world, it would be a cow next to a cow next to a cow and then a chicken.”
Wild animals are not the only group of organisms that have been substantially impacted by humans. The researchers found that human activities have cut the amount of plant biomass in half.
“Even though short in numbers, we have managed to throw a lot of sand in the air and mess up a lot of things,” said Harvard biologist E.O. Wilson.
“I would hope this gives people a perspective on the very dominant role that humanity now plays on Earth,” Milo told The Guardian. “It is definitely striking, our disproportionate place on Earth.”
The study is published in the Proceedings of the National Academy of Sciences.
By Chrissy Sexton, Earth.com Staff Writer