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Monday, 14 December 2020

The mass of objects built by humans now exceeds that of all living things


While the natural world continues to shrink, the ‘anthropogenic mass’ – the mass of all human-made materials created since the Industrial revolution, including houses, cars, roads, and aeroplanes – has grown. Indeed, the number of so-called technospecies has far surpassed the estimated 9 million biological species on the planet, according to a new groundbreaking study published on 10 December in the journal Nature. 


The team of scientists from the Weizmann Institute in Israel performed a rigorous and meticulous analysis of the balance between man and nature. More specifically, they examined changes in global biomass and human-made mass from 1900 to the present day and found that the mass of human-made materials has now reached the same mass as that of all living organisms on Earth.

The researchers estimate that the Earth’s biosphere now weighs less than 1.2 trillion tonnes of dry mass (not including water) considering the mass of all life on Earth including all the fish in the sea, microbes in the soil, trees on land, birds in the air, and more, with trees making up most of this mass.

Buildings and infrastructure made of concrete and aggregates currently make up the bulk of
human-made mass – around four-fifths – followed by bricks, asphalt, and metals. Surprisingly, the mass of plastics makes up a relatively small proportion of the total anthropogenic mass, yet still far exceeds the mass of all animals on land and marine creatures combined, the study estimates. The anthropogenic mass only included embedded in inanimate solid objects made by humans and does not include waste.

The shift to a world dominated by human-made materials is being driven mainly by increased consumption and urban development. Each week, every person in the world generates, on average, more than their own body weight in human-made matter. The footprint of humanity has been doubling every 20 years, the researchers say.

The new findings support recent calls to recognise a new epoch called the Anthropocene to account for the profound impacts of human activity on the Earth. The authors write: “The impacts of these activities have been so abrupt and considerable that it has been proposed that the current geological epoch be renamed the Anthropocene. Our study rigorously and quantitatively substantiates this proposal”.

At the beginning of the 20th century, the mass of human-produced objects was equal to about 3 per cent of the world’s total biomass but in 2020, has reached about 1.1 teratonnes, exceeding overall global biomass. Moreover, this dramatic increase in human constructions has been accompanied by significant losses in biomass. Humanity has roughly halved the mass of plants since the first agricultural revolution, the authors say.

“While modern agriculture utilises an increasing land area for growing crops, the total mass of domesticated crops is vastly outweighed by the loss of plant mass resulting from deforestation, forest management and other land-use changes”, they write, “These trends in global biomass have affected the carbon cycle and human health”.

By painting a more vivid picture of the balance between humans and nature, the researchers are hoping to draw attention to the fact that the natural world is not infinite like so many seem to believe. If human production continues at this rate, the weight of our impact will exceed 3 teratonnes by 2040, almost tripling the mass of living things.


Reference:

Elhacham, E. et al. Global human-made mass exceeds all living biomass. Nature (2020). DOI: 10.1038/s41586-020-3010-5

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