Ages of human history have often been named after the materials that our ancestors mastered at that time: stone, bronze or iron.
If future archaeologists do the same for us, what material might they choose to define the 21st Century? Silicon? Plastic? Both are candidates, shaping the world for better and for worse. But if the decision were based on scale alone, then there can be only one answer: we are living in the age of concrete.
There are few human-made substances on Earth that are quite so ubiquitous. Concrete is what the philosopher-ecologist Timothy Morton calls a "hyperobject" – something so enormous and widespread that it cannot be fully contemplated with the mental faculties that we have. If you attempt to picture the entirety of the world's concrete in the mind's eye, you soon realise that it's impossible.
However, Emily Elhacham of the Weizmann Institute of Science and colleagues recently attempted to give it a shot. Their goal was to better understand humanity's impact during the Anthropocene by totting up the weight of all inanimate human-made objects on Earth. As part of their calculations, they found that concrete accounts for around half of all human-made things – the single biggest category of anthropogenic material. And if its rate of growth continues, it will overtake the total weight of Earth's biomass sometime around 2040.