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Received: 1 November 2019
Accepted: 9 October 2020
Published online: 9 December 2020
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Humanity has become a dominant force in shaping the face ofEarth1-9. An emerging question is how the overall material output of human activities compares to the overall natural biomass. Here we quantify the human-made mass, referred to as 'anthropogenic mass', and compare it to the overall living biomass on Earth, which currently equals approximately 1.1 teratonnes10,11. We find that Earth is exactly at the crossover point; in the year 2020 (± 6), the anthropogenic mass, which has recently doubled roughly every 20 years, will surpass all global living biomass. On average, for each person on the globe, anthropogenic mass equal to more than his or her bodyweight is produced every week. This quantification ofthe human enterprise gives a mass-based quantitative and symbolic characterization of the human-induced epoch of the Anthropocene.
The face of Earth in the twenty-first century is affected in an unprecedented manner by the activities of humanity and the production and accumulation of human-made objects. Given the limitations of human cognition in the face of the immensity of the globe and the seeming infinity of the natural world, it is desirable to provide a rigorous and objective measure of the overall balance between the living and human-made. However, in spite of pioneering efforts1-8, we lack a holistic picture that quantifies and compares the composition of the world in terms of both biological and human-made mass.
A case in point is our planet's biomass. While the mass of humans is only about 0.01% of global biomass, our civilization had already had a substantial and diverse impact on it by 3,000 years ago9. Since the first agricultural revolution, humanity has roughly halved the mass of plants, from approximately two teratonnes (Tt, units of 1012 tonne; where estimates are on a dry-mass basis) down to the current value10 of approximately 1 Tt. While modern agriculture utilizes an increasing land area for growing crops, the total mass of domesticated crops (about 0.01 Tt)11 is vastly outweighed by the loss of plant mass resulting from deforestation, forest management and other land-use changes10. These trends in global biomass have affected the carbon cycle and human health12,13. Additional human actions, including livestock husbandry,...