Materials and Civilization: An Overview of Material Use and Dematerialization

Imagine the vastness of human civilization's material footprint — a footprint so large that it stretches beyond the materials we see and touch, extending into the hidden flows of earth, rock, and soil moved to extract the resources that build our world. Understanding what truly counts as material use is the first step to grasping the scale and impact of our civilization. We often think of materials as the metals, wood, and stone that form our buildings, vehicles, and tools, but beneath this visible layer lies a massive movement of 'hidden flows' — earth displaced during mining, soil eroded from fields, and materials moved during construction. These hidden flows can constitute more than 70% of the material output in industrialized countries, yet their quantification is fraught with uncertainty.

Take, for example, the overburden removed during bauxite mining: for every ton of aluminum ore extracted, nearly half a ton of earth must be displaced and set aside. Similarly, iron ore extraction can involve moving two tons of overburden per ton of ore. These numbers reveal that the physical scale of material disturbance is far greater than the material ultimately used.

Yet, when we consider what to include in national material accounts, choices must be made. Oxygen, for instance, is consumed in enormous quantities during the combustion of fossil fuels — burning one kilogram of coal requires 2.67 kilograms of oxygen. Globally, this adds up to around 21 gigatons of oxygen consumed annually. But because oxygen is so abundant in the atmosphere, including it in material flow accounts would overshadow all other materials, turning the measure into a proxy for fossil fuel use rather than material stocks. This is why oxygen is typically excluded, despite its importance in energy processes.

Water presents a similar challenge. The volume of water withdrawn for industrial, agricultural, and municipal use dwarfs the mass of all other materials combined. In the United States alone, water withdrawals exceed 5 gigatons annually, while the total mass of other materials used is less than 4 gigatons. However, much of this water is non-consumptive, such as cooling water used in power plants, which is returned to the environment almost immediately. Irrigation water mostly evaporates or transpires back into the atmosphere, continuing the natural water cycle. Because of these unique characteristics, water is better treated separately from solid material flows to avoid skewing analyses.

These decisions — what to include and exclude — shape our understanding of material use and its environmental implications. They also highlight the complexity of measuring the true material footprint of modern societies. As we move forward, we will explore how these material flows evolved throughout history, how humans have transformed and innovated with materials, and what this means for our future. Let us now embark on the journey through the rich history of human material development.