The single most abundant element in the Earth’s crust is oxygen making up 46.6 percent of the mass. The second most abundant element is silicon making up 27.7 percent, mostly in the form of various molecules combining silicon and oxygen. Silicon dioxide is the kind people are familiar with and it is found on most, but not all beaches of the world.
It just doesn’t seem reasonable to be concerned that we will somehow run out of sand. After all, the estimated weight of the Earth is 1.3 x 1025 pounds (13 followed by 24 zeros) or 6.5 x 1021 tons. The crust makes up 1 percent of that total weight, so the crust weighs 6.5 x 1019 tons. Of that, 27.7 percent is silicon or 1.8 x 1019 tons. The world consumes about 50 billion tons a year. For comparison’s sake, that’s 5 x 1010 tons annually—which if you do the math means we will run out of sand from the Earth’s crust in 360 million years at current rates of consumption.
But, of course, not all sand is created equal. Much of it is unsuitable for industrial purposes such as making concrete or proppants in hydraulically fractured oil and gas deposits (fracking). The shape and uniformity of sand grains are crucial in certain uses such as proppants (which keep fractures open once they’ve been made). Sand casting (used to make metal objects) requires a mixture of three different kinds of sand, each with a different chemical formula. Sand of particularly high purity is required for glass-making and for solar panels and computer chips.
Desert sand is too fine and wrongly shaped for almost all industrial and consumer uses and is never used to make concrete, the principle use of sand. Much of the best sand comes from riverbeds, the mining of which has many nasty environmental side-effects.
And, of course, the sand in the Earth’s crust is not uniformly distributed; nor is most sand available since it is too deep for economical recovery. The Earth’s crust run 5 to 10 kilometers deep under the oceans and 30 to 50 kilometers deep under continents.
Sand is used in so many products and processes in our modern life, that our civilization would be unthinkable without it. And therein lies the problem. As the BBC reported in 2019, “The demand for that material is so intense that around the world, riverbeds and beaches are being stripped bare, and farmlands and forests torn up to get at the precious grains.”
One of the biggest uses of sand is to create additional land in coastal areas. More than 5,000 square miles have been added to the world’s coasts since 1985.
To give you a sense of how much the tempo of sand consumption is increasing, a piece in Yale Environment 360 points out that “[a]round 60 percent of sand use worldwide is in China, which is estimated to consume more sand in three years than the U.S. consumed in the entire 20th century.”
The same article details some of the environmental damage in China and elsewhere as entire river watersheds are altered in ways that tend to increase flooding, undermine marine life, collapse riverbanks, and reduce the amount of water in natural lakes linked to river systems. And, it turns out that river sands are being consumed much faster than they can be replenished.
Whether, as suggested in the previously cited Nautilus article, the world will run out of sand suitable for all the purposes for which it currently wants sand by 2050 cannot be known. But it is a straw in the wind that a resource that the vast majority of people consider inexhaustible is now considered threatened even by such mainstream sources as the United Nations Environment Program and the World Economic Forum. If even the sand beneath our feet is threatened, what other resources are we exhausting that have escaped our awareness? Fertile topsoil comes to mind. So do fresh water and petroleum.
Photo: Sand dunes at Al-Tawqi, northeast of Riyadh, Saudi Arabia (2002). By Meshari Alawfi. Via Wikimedia Commons https://commons.wikimedia.org/wiki/File:Sand_Dunes_sa.jpg .