Natalie Parletta
Natalie Parletta is a freelance science writer based in Adelaide and an adjunct senior research fellow with the University of South Australia.
Among its other dubious distinctions, the year 2020 marks the approximate tipping point between anthropogenic mass and living biomass, scientists say.
The Israeli team has calculated that the mass of human-made products exceeds that of all of the Earth’s plants, microorganisms, people and animals.
And this mass is now doubling around every 20 years, they write in the journal Nature. At that rate it could be more than triple that of the Earth’s dry biomass by 2040.
Defined as “the mass embedded in inanimate solid objects made by humans (that have not yet been demolished or taken out of service)”, anthropogenic mass includes infrastructure and products made with concrete, asphalt, bricks, metals, glass and plastic.
Construction materials comprise the vast bulk of it, and building and infrastructure mass recently surpassed that of all trees and bushes. Plastic goods outweigh all terrestrial and marine animals put together.
The researchers, led by Emily Elhacham from the Weizmann Institute, estimate that human-made mass in New York City roughly equals that of all the world’s fish, and Egypt’s Great Pyramid of Giza equates to a temperate forest about the size of Kyoto, Japan.
They calculate that the Eiffel Tower weighs around as much as the world’s remaining 10,000 white rhinos.
The team merged data from other surveys to make their comparisons and create a complete picture of the world’s human-created and biological mass, estimated from the beginning of last century in teratonnes (each equivalent to 1000 gigatonnes).
A chunk of our impact resulted from diminishing living biomass. It’s estimated that we have halved plant mass through deforestation and other land-use changes, from around two teratonnes to one, since the first Industrial Revolution.
In 1900, the team reports, anthropogenic mass comprised 3% of the Earth’s biomass. It’s taken just 120 years for it to exceed 100%.
Some trends they highlight include replacing bricks with concrete for construction in the mid-1950s and using asphalt as a key material for roads from the 1960s. Other shifts occurred following global events such as world wars and economic crashes.
“Most notably, continuous increases in anthropogenic mass, peaking at over 5% per year, mark the period immediately following World War II,” they write. “This period, frequently termed the Great Acceleration, is characterised by enhanced consumption and urban development.”
The authors add that their study offers a new dimension to our understanding of human impacts on the planet and the sweeping ramifications for natural habitats, biodiversity and climatic and biogeochemical cycles, cementing our notoriety in the current epoch.
It “provides a symbolic and mass-based quantitative characterisation of the Anthropocene”, says senior author Ron Milo.
“Given the empirical evidence on the accumulated mass of human artifacts, we can no longer deny our central role in the natural world. We are already a major player and with that comes a shared responsibility.”