A. Cearreta
We can now quantify how much humans have changed the surface of the planet. A scientific analysis of all the human-made substances on Earth—including "houses, factories, farms, mines, roads, airports and shipping ports, computer systems, [and] discarded waste"—reveals their total mass to be 30 trillion tons. That's a mass of more than 50 kilos for every square meter of the Earth's surface. Impressive!In a paper for The Anthropocene Review, University of Leicester geologist Jan Zalasiewicz and his colleagues describe how they arrived at this number. Zalasiewicz has devoted much of his career to studying the Anthropocene, a geological period that begins in the twentieth century and is characterized by human-created substances such as plastic and radioactive isotopes from nuclear weapons testing.
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