According to the researchers, humans have destroyed 83% of wild mammals and 50% of plants despite being only 0.01% of life forms.
The National Academy of Sciences of the United States published a study whose objective was to catalog the mass of all living things on Earth but also found that humans have ruined most of it despite constituting only a small portion of the biosphere. Humans make up only 0.01% of biomass on Earth, but they have managed to wipe out 83% of all wild mammals and cut biomass in half during our time on this planet, according to the study. When we look specifically at mammals, humans make up 36% of all mammals on the planet and wild animals like lions and bears just 4%.
"In the relatively short span of human history, major innovations, such as the domestication of livestock, the adoption of an agricultural lifestyle, and the Industrial Revolution, have dramatically increased the human population and had radical ecological effects," noted the biologists Yinon Bar-On, Rob Phillips and Ron Milo.
The distribution of biomass on Earth
This is the name of the study that practically consists of a census aimed at quantifying the mass of life on the planet measured in tons of carbon, a common unit of measurement to quantify the plant mass, since it is independent of the water content, in addition to allowing comparisons with any other living being.
This has led researchers to discover that all life on the planet consists of some 550 billion tons of carbon distributed among all the kingdoms of life. However, the study also revealed that the rise of human civilization has caused the destruction of 83% of wild mammals, 80% of marine mammals, 50% of plants and 15% of fish.
Source: The Guardian.
In addition, currently, of the total of terrestrial mammals, only 4% correspond to wild animals, while 60% are made up of livestock, and the remaining 36% are human beings.
Plants rule the land and animals rule the sea
The study provides other interesting data such as that plants constitute the dominant kingdom on the planet with 450 gigatons of carbon (450 Gt C), concentrated mainly on land, while animals (2 Gt C) are mainly marine.
As for humans, their mass is an order of magnitude (10 times) greater than that of all wild mammals combined, and their historical impact on global biomass is more than remarkable: "Today, the biomass of humans (0.06 Gt C) and the biomass of cattle (0.1 Gt C) far exceed that of wild mammals (0.007 Gt C) ”, point out the scientists.
Source: The Guardian.
"This is also true for wild and domesticated birds, for which the biomass of domesticated birds (0.005 Gt C, mainly chickens) is approximately three times higher than that of wild birds (0.002 Gt C)."
“In fact, humans and livestock outnumber all vertebrates combined, with the exception of fish. Although humans and livestock dominate the biomass of mammals, they are a small fraction of the animal biomass, comprising mainly arthropods, followed by fish, ”the study highlights.
Impact of human activity on the composition of the biosphere
For researchers, comparing current world biomass with pre-human values is very difficult to estimate accurately, however it allows to demonstrate the impact of humans on the biosphere. For the scientists Bar-On, Phillips and Milo, "human activity contributed to the Extinction of the Quaternary Megafauna between 50,000 and 3,000 years ago, which demanded about half of the large species of terrestrial mammals." "The biomass of wild land mammals before this extinction period was estimated by Barnosky at 0.02 Gt C". However, "the current biomass of wild terrestrial mammals is approximately seven times lower (0.003 Gt C)".
Regarding marine mammals, the census indicates that “intense whaling and exploitation of other marine mammals have resulted in a reduction of approximately five times in the global biomass” of these animals.
"While the total biomass of wild mammals (both marine and terrestrial) decreased by a factor of 6, the total mass of mammals increased approximately four times." This "due to the great increase in the biomass of humanity and its associated livestock."
“Human activity has also affected the world populations of vertebrates, with a decrease in the total biomass of fish, an amount similar to the total biomass remaining in fisheries and the increase in the total biomass of mammals due to livestock farming. ”.
The impact of human civilization on global biomass has not been limited to mammals, but has also profoundly modified the total amount of carbon sequestered by plants: “A worldwide census of the total number of trees, as well as a comparison of biomass actual and potential plant biomass, has suggested that the total biomass of plants (and, by delegation, the total biomass on Earth) has decreased approximately twice its value before the beginning of human civilization.
Furthermore, the study adds that the total biomass of human crops "represents only 2% of the total existing plant biomass."
However, there has been little success with caring for the subsoil in the most productive areas, and no large organized movements have been generated to prevent the expansion of the consumption of livestock meat, undoubtedly central axis in the advance of soy, corn and soy plantations. other monocultures over forested areas on all continents.
On the other hand, in the fishing sector, the tonnes of catches have been stable for thirty years and at the same time aquaculture has grown exponentially, reaching around 44% of all fish production.
From the report many questions are opened, and it serves to reassemble our conceptual framework of the biosphere. Or furthermore, that of Gaia, that living organism with less and less body mass for its vital needs, in which we lodge like bacteria in our intestines.
With information from: