Since the first agricultural revolution, human activities have greatly changed the face of the earth. Humans have reduced plant biomass by half through activities such as agriculture and logging. At the same time, the continuous production and accumulation of man-made objects have made the earth’s living biomass and The balance between man-made masses has changed.
So, what is the total weight of man-made materials in the world at present? How does it compare with the weight of natural organisms?
Today, a study published in Nature pointed out that 2020 may mark a turning point where man-made mass exceeds the global living biomass. For the past 100 years, the mass of man-made objects such as buildings, roads, and machines has doubled every 20 years. On average, every person on the planet produces an artificial mass that exceeds his body weight every week. Such a result reminds us that the human influence on the earth is increasing.
(Source: Nature)
In this regard, Ron Milo and colleagues from the Department of Plant and Environmental Sciences of the Weizmann Institute of Science in Israel stated that at the beginning of the 20th century, the mass of man-made objects was equivalent to about 3% of the total biomass; today, the man-made mass has surpassed the global mass. The total biomass, today's total global biomass is around 1.1 trillion (trillion, the same below) tons. According to current trends, man-made mass is expected to exceed 3 megatons in 2040, which is almost three times the total dry weight of the earth’s living things.
Although the number of humans accounts for only 0.01% of the total amount of living things in the world, humans have had a huge impact on the earth as early as 3000 years ago.
Since the first agricultural revolution, humans have reduced the number of plants from approximately 2 megatons to half through land use changes such as agriculture and logging. As modern agriculture occupies more and more land to grow crops, the total quality of crops far exceeds the amount of plants lost due to deforestation. These global biomass changes affect the carbon cycle and human health.
In addition, other human behaviors (such as animal husbandry, hunting, and overfishing) greatly affect biodiversity. A recent survey found that the vast majority (about 90%) of the living organisms on the earth are plants, followed by bacteria, fungi, archaea, protists and animals.
Human activities in the 21st century, the production and accumulation of man-made objects have brought unprecedented impact to the earth. With the acceleration of human influence on the world, quantitative assessment and monitoring of material flows in the socio-economic system have become more and more urgent. How to compare biomass and man-made mass is also a difficult problem.
(Source: outh Ki Awaaz)
Researchers from the Department of Plant and Environmental Sciences of the Weizmann Institute of Science in Israel evaluated the changes in global biomass and man-made mass from 1900 to the present, and analyzed the relationship between the two main man-made masses and total biomass. Among them, biomass refers to the total global mass of all living organisms, and humans themselves (and their livestock) are also part of global biomass; man-made mass refers to inanimate solid matter manufactured by humans (equipment that has not been dismantled or decommissioned, also known as " Man-made large-scale waste").
By analyzing the dry weight of global biomass and man-made mass, researchers found that man-made mass has increased rapidly in the past 100 years, doubling almost every 20 years. However, the total biomass did not change significantly. In the past 5 years, the artificial mass has reached 30 billion tons per year, which is equivalent to the artificial mass that each person produces every week that exceeds his body weight. As a result, the gap between man-made mass and total biomass has rapidly narrowed.
At the beginning of the 20th century, man-made mass was only 3% of global biomass. By 2020, man-made mass has surpassed global biomass. Most of the man-made quality comes from buildings and roads; others also include plastics and machines.
Figure | Since 1900, biomass dry weight and man-made quality curve diagram (source: Nature)
The researchers also compared the total biomass wet weight and man-made mass, and compared the accumulated man-made mass waste. Man-made quality waste refers to man-made materials that have been dismantled or decommissioned (excluding large unused ore such as mining and landscape reconstruction). If these wastes are taken into account, the dry weight of biomass exceeded the total biomass in 2013. Calculated by wet weight, the current total biomass is about 2.2 megatons, and the man-made mass will exceed the total biomass in 2030.
Figure | Since 1900, biomass wet weight and man-made quality curve diagram (source: Nature)
In addition, the researchers also compared the main man-made mass and biomass. The main man-made quality categories are construction and infrastructure (concrete, aggregate, brick and asphalt), and the main total biomass categories are trees and shrubs. Research has found that the first two main man-made qualities have recently surpassed the latter. Similarly, the total amount of global plastic production is more than the total amount of all land and marine animals.
Figure | Key components of global biomass and man-made quality in 2020 (Source: Nature)
Studies have shown that the changes in the composition of man-made masses show the trend of road development since the 20th century. For example, in the mid-1950s, brick-based buildings were gradually transformed into concrete buildings, and asphalt began to be used as the main road material in the 1960s. In addition, man-made quality changes are related to global events such as world wars and major economic crises. After the Second World War, man-made mass continued to increase, reaching a maximum of more than 5% per year. This period is called the "great acceleration" and is characterized by increased consumption and urban development.
The author points out that the exact time of the turning point depends on the definition, so there may be some fluctuations in the estimation results. Using dry weight, wet weight estimates, or other definitions of quality categories, transitions may still occur in the past, present, or future ten years. If the current trend continues, by 2040, the man-made mass, including waste, will exceed 3 megatons, which is almost three times the total dry weight of the earth’s organisms.
The accumulation of man-made mass in this study mainly comes from the transformation of rocks and minerals. In this process, humans transform near-surface mineral deposits into useful ways for society. In this way, it is important for natural habitats, biodiversity, and various climates and organisms. The geochemical cycle has a wide range of effects.
In view of the large and rapid development of human activities on the earth, the current geological era can be renamed the Anthropocene .
Reference materials:
https://www.nature.com/articles/s41586-020-3010-5