A multinational team of geologists made a rough estimate of the size of the physical structure of Earth’s technosphere - finding that its mass approximates to 30 trillion tons. That's a mass of more than 50 kilos for every square meter of the Earth's surface.
The researchers define the physical technosphere "the summed material output of the contemporary human enterprise". This includes houses, factories and farms, but also cars, computers, smartphones, light bulbs, oil rigs, pens and CDs. Also the growing residue layer of waste material in landfills, spoil heaps, plastics in the oceans, space junk in orbit, as well as one trillion tonnes of human-created carbon dioxide in the atmosphere, are included in their evaluation.
As a thought experiment, the geologists also tried to imagine what the technosphere would look like to future geologists. 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". Additionally the team concludes the total mass of the current technosphere is "five orders of magnitude greater than the standing biomass of humans presently sustained by this construct", as the total sum of dry biomass for all humans alive on the planet is appraised at a mere 100 million tons.
If humans would disappear from the face of the Earth today, we would still leave 30 trillion tons of mass in the geological record. Certainly, "we were here" is written all over.
The research is published in the Anthropocene Review.