The sum total amount of material we have dug out of the ground in the past century is a figure so big that even the numerical unit itself is rarely ever used: a teratonne. Or rather 6.7 teratonnes (or, to be even more precise, 6,742,000,000,000 tonnes). Given the combined weight of every object manufactured by humankind is, according to one estimate, around 1.1 teratonnes, here is another way of looking at it: for every human-made object on this planet, every building, plane, train, car and phone, try to picture a pile of earth, sand and dirt six times its weight. And the pile of moved
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