A. Cearreta

Leinfelder and Scheffold

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.

The term "technosphere" was invented by Duke University environmental engineer Peter Haff, said Zalasiewicz in a statement. He added that it functions like other ecosystems, in that it has emergent properties: "Humans and human organisations form part of it, too—although we are not always as much in control as we think we are, as the technosphere is a system, with its own dynamics and energy flows."

In their paper, Zalasiewics and colleagues describe how the technosphere stretches from above the Earth's crust where we find the built environment and farms, as well as the subterranean world with its pipelines and mines. The technosphere includes waste in the oceans, as well as 1 trillion tonnes of human-created carbon dioxide in the atmosphere and space junk in orbit.

As a thought experiment, the researchers tried to imagine what the technosphere would look like to geologists of the distant future. They describe how "technofossils" might survive into the future:

As with biological species, not all technofossils will be recognizable following the information loss associated with fossilization. Future fossilized books, for instance, will likely be rectangular carbonized masses classifiable by size and relative dimensions and subtle variations in surface texture; fragmentary details of the print information will only be rarely preserved, as are fragmentary details of DNA structure in some exceptionally preserved ancient fossils today.

Mobile phones, they point out, may have good "fossilization potential."

Trying to account for the techosphere might prove difficult for future geologists. As the researchers point out, the total mass of the current technosphere is "five orders of magnitude greater than the standing biomass of humans presently sustained by this construct." Of course, humans aren't exactly sparse upon the Earth. Currently, human biomass "is more than double that of all large terrestrial vertebrates that characterized the Earth prior to human civilization and is an order of magnitude greater than present wild terrestrial vertebrate biomass."

Not only do humans represent more mass than their animal predecessors, but we also have a unique ability to generate stuff to sustain ourselves. After all, the technosphere is something we've created to make our survival more comfortable. We sustain it, enhance it, and shape it every day.

This insight allows us to understand the magnitude of human activity upon the Earth. We are busy, inventive animals, and we leave countless novel materials behind. That said, the technosphere is in a constant state of flux. Humans have an opportunity to change its dynamics and alter the fossil record we're leaving behind. In the end, we could make the geological period after the Anthropocene look a lot more like the Pleistocene that preceded it.

The Anthropocene Review, 2016. DOI: 10.1177/2053019616677743

Listing image by A. Cearreta