We Miss the Forest for the Concrete - Little, Big Science : Little, Big Science

From urban areas to primeval landscapes, almost every corner of Earth is influenced by humans. Quantitative studies show that the building materials, waste, and technological products we produce now outweigh everything alive on the planet. And this is not a projection, but an assessment of the current balance.

The first comprehensive quantitative estimate of global biomass was published in a 2018 study led by Dr. Yinon Bar-On and Professor Ron Milo of the Weizmann Institute [1]. Global biomass refers to the dry mass of all living organisms on Earth, measured by their carbon content. Carbon was chosen as the metric because it is the principal element in the biological molecules, such as proteins, sugars, and lipids, that make up all living organisms. The proportion of carbon in an organism remains fairly constant among similar organisms worldwide. All trees, for example, will have similar carbon content, making carbon a convenient, uniform index for comparing biological masses on a global scale.

To estimate the total amount of carbon present in all living organisms on Earth, the researchers compiled data from various sources including terrestrial and marine field measurements, satellite-based assessments, global ecological models, and macro-level data (e.g. the total area of forests worldwide) from fields such as agronomy, marine biology and microbiology. For example, satellites can be used to gauge tree density in certain regions, while field samples from tree trunks provide the average carbon content per trunk. Multiplying these values by the area of the forest yields biomass estimates. The same principle is applied to croplands, pastures, marine habitats, and other systems until a global picture of biomass emerges.

The researchers calculated the total biomass and estimated a total of about 550 gigatons (550 billion tons) of carbon. Roughly 80 percent of this comes from plants, primarily terrestrial trees. About 15 percent of the biomass belongs to bacteria and archaea, an entire domain of microorganisms, most of which live in soil and on the seafloor. The remaining five percent is divided among fungi, protists (a mostly microscopic organisms), animals, and humans. Combined, all animals including insects, fish, birds, and mammals, make up less than three percent of total biomass. The biomass of humans is about 0.06 gigatons of carbon, accounting for just 0.01 percent of the total.

Two years later, the same research group published another paper proposing a different global estimate [2]. This time they estimated the mass of material produced by humans rather than biological matter. The researchers compiled production and consumption data for construction materials, metals, plastics, glass, textiles, industrial waste, and other products. They created a model that computes the total mass of “anthropogenic material”, material originating from human activities. The model incorporated production volume as well as the lifespan of different materials, distinguishing between long-lived materials such as concrete and short-lived materials such as paper. According to their calculations, the mass of anthropogenic material had surpassed the mass of all living matter by 2020. The calculations also showed that in that year, the annual production rate of human-made materials was approximately 30 gigatons per year, a figure that likely continues to rise.

Global estimates are inherently difficult, and such figures inevitably carry substantial uncertainty. Much of the uncertainty in the biomass estimates stems from the difficulty of accurately measuring tree root mass in tropical regions or the number of bacteria deep within the soil. For this reason, pinpointing the exact year when artificial material overtook living matter is challenging.

Nevertheless, although global estimates are based on assumptions whose validity can be questioned, technological advances in measurement and data analysis are continuously improving scientists’ ability to assess worldwide metrics. In recent years, new tools have been introduced to improve the accuracy of global biomass estimates. In April 2025, ESA launched a Biomass research satellite, the first of its kind to use penetrating radar to measure tree mass even in dense forests and other difficult-to-survey areas [3]. These measurements are expected to substantially improve terrestrial biomass models. Additional satellite systems such as GEDI, mounted on the International Space Station, ESA's Copernicus satellites, and JAXA's ALOS-2 [4], have provided relatively high-resolution three-dimensional data in recent years. These systems are complimented by machine-learning methods that estimate tree mass at every point on Earth. Despite the considerable uncertainty in current estimates, the trend is clear: there are more “objects” than living things.

The term "anthropogenic material" refers to a wide range of substances that have been manufactured or processed by humans. It is estimated that most of this mass consists of construction materials. Concrete alone accounts for over 40 percent of the total anthropogenic mass, followed by bricks, asphalt, and structural metals such as steel. Other components include plastics, glass, processed wood, textiles, paper, and electronics, though these account for a smaller percentage of the total mass. The global distribution and rate of decay of materials such as plastic and organically sourced materials like paper, cardboard, and cotton vary. In contrast, heavy, durable materials, such as concrete and metals, accumulate over decades or even centuries, driving the ongoing increase in anthropogenic mass.

The mass of human-made material continues to grow. According to the latest estimates, the total mass of anthropogenic material—that is, everything built, manufactured, or assembled by humans—reached approximately 1,400 gigatons in 2024 [5], (This interactive site displays the mass of different types of materials on Earth and includes explanations—highly recommended!). This represents a steep increase compared with the previous decade. For example, a 2023 study shows that the accumulation rate of anthropogenic material continues to rise alongside global economic output and that total-mass estimates are expected to grow in the coming decades [6]. Anthropogenic mass doubles roughly every 20 years, meaning that most of it has been created within our lifetimes!

Often, human development does not coexist with nature, but rather comes at its expense. Many areas that once supported natural ecosystems have been converted for agriculture, industry, and infrastructure. This damage is not merely the loss of landscapes and species, it also significantly harms us. Clean water, breathable air, food, and protection from floods and diseases are all invaluable ecosystem services [7]. When we destroy these systems, we are forced to devise costly solutions to problems that we created ourselves. Fortunately, governments, companies, and municipalities are increasingly recognizing that conservation is a vital economic strategy, not just a romantic ideal. The question is not only how to protect what remains, but also how to ensure that there will be something left to support us all in the future. If we fail to wisely safeguard and manage the natural systems that sustain humanity, we will have nothing to build on.

Hebrew editing: Galia Halevy-Sadeh
English editing: Gloria Volohonsky

Abbreviations:

ALOS - Advanced Land Observing Satellite

ESA - European Space Agency

GEDI - Global Ecosystem Dynamics Investigation

JAXA - Japan Aerospace Exploration Agency

References:

By:

Yuval Jacobi, PhD

Yuval is a marine biologist with a PhD from the Technion, and is currently a postdoc at MIT. He studies sea bacteria and enjoys doing field work, via scuba diving or on-board research ships. Yuval believes in the power of second chances. He is a father, partner, nature lover and foodie.

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