Fifty Billion Tonnes

There is a well worn fact about Dubai that is usually told as a joke. A city standing in one of the largest deserts on earth, surrounded by sand in every direction, has to buy the sand it builds with.

The joke is roughly true and the reason is not economics. It is the shape of the grains.

Why the desert is no use

Sand is not one substance. It is a size category, anything from about a sixteenth of a millimetre to two millimetres across, and what matters for building is what the individual grains look like and how evenly the sizes are spread.

Concrete is a lattice. Cement paste glues together a skeleton of stone and sand, and the strength comes from the aggregate locking against itself while the cement holds it in place. For that you want angular grains with sharp faces and corners, and you want a wide mixture of sizes, so the small ones sit in the gaps between the big ones and there is very little space left for cement to fill.

Wind blown desert sand is the opposite on both counts. Grains carried by air bounce against each other continuously for thousands of years, and every collision knocks a corner off. What survives is round, polished and remarkably uniform in size. Pour that into a mix and the grains roll over each other instead of interlocking, and because they are all much the same size there are gaps everywhere.

It can be used with blending and treatment. It cannot be the principal fine aggregate in structural concrete on its own. So the sand that goes into a tower in a desert city comes from crushed rock, from quarries, from riverbeds and from the seabed, and where the specification demands it, from somewhere else entirely.

Water does the opposite of wind

The sand that works is made by water. Rivers break rock and carry the fragments, and because water is dense the grains are cushioned rather than sandblasted, so they arrive at the delta still angular. A riverbed is a sorting machine that has spent a few thousand years producing exactly the material a concrete plant wants.

Which is why the extraction happens in rivers, deltas and shallow seas rather than in deserts, and why the environmental argument about sand is really an argument about rivers.

The scale

The United Nations Environment Programme published a report on this in May 2026, written by twenty seven authors, and the headline figure is the one worth memorising.

Fifty billion tonnes a year. Sand and gravel are the second most extracted material on the planet, behind only water. Extraction is roughly five times what it was in 1970, and the use of sand in buildings alone is projected to rise by as much as 45 per cent by 2060.

For a sense of proportion, fifty billion tonnes is several tonnes for every person alive, every year, of one material that almost nobody thinks about.

Dead sand and alive sand

The report makes a distinction that is worth borrowing, because it reframes the whole problem.

Sand that has been dug up and turned into concrete, asphalt or glass is dead sand. It has left the natural system and it is not coming back. Sand still sitting in a river, a delta or a coastline is alive sand, and it is doing work while it sits there.

That work is not sentimental. Sand in a riverbed filters water on its way to an aquifer. It regulates how a river flows and where it goes. On a coast it is the thing that absorbs a storm surge, and it is what keeps salt water from pushing inland into the fresh water underneath farmland.

Both uses are real and they are in direct competition. Every tonne that becomes a floor slab is a tonne that has stopped protecting a shoreline.

The sand gap

The report's central claim is that extraction is running faster than rivers can produce replacement. That is what it calls the sand gap, and it is the same shape of problem as pumping groundwater faster than rain refills it.

The consequences are visible where the mining is heaviest. Riverbeds drop, which pulls the water table down with them and leaves wells and pump intakes dry. Banks collapse because the material holding their feet has gone. Bridge piers and embankments lose the sediment they were founded in. Deltas that were being topped up by sediment from upstream stop being topped up, and start losing ground to the sea.

Why nobody is in charge of it

Sand is governed badly almost everywhere, and the reason is that it is cheap, heavy and local.

Because it is cheap per tonne, it is not worth transporting far, so the market is thousands of small local ones rather than a single global one that a single regulator could watch. Because it is heavy, the profit is in extracting close to where it will be poured, which means close to the town it is being taken from. And because it is sand, it does not feel like a mineral to the people writing mining law. Oil and copper get ministries. Sand gets a permit from a district office, if that.

The result is an enormous industry, much of it informal and some of it violent, moving the second most extracted material on earth largely outside the framework that governs the extraction of anything else.

What the report asks for

Its recommendations are unglamorous and mostly about counting. Measure how much is being taken and from where. Treat sand as a strategic resource in national planning rather than as a nuisance in a riverbed. Coordinate between the countries that share a river, because a delta starves in one country when the dredging is done in another. Use less of it by recycling demolition waste and by substituting manufactured sand from crushed rock where the specification allows.

None of that is a technology problem. The material for a substitute exists in every quarry.

The awkwardness is that the countries doing the most building are also the ones with the least appetite for slowing it down, and that a tonne of river sand taken without a permit is cheaper than a tonne of crushed rock produced with one.

Sources

• United Nations Environment Programme and GRID-Geneva, "Sand: wanted dead and alive. Use it wisely, warns the UN", press release carried by Wetlands International (the report Sand and Sustainability: An Essential Resource for Nature and Development, prepared by 27 authors; the extraction rate of 50 billion tonnes of sand and gravel a year; sand and gravel being the second most used resource worldwide after water; the projection that use in buildings alone will rise by up to 45 per cent by 2060; the distinction between dead sand, lost from natural systems once turned into concrete, asphalt or glass, and alive sand in rivers, deltas and coastal zones; the functions of alive sand in filtering water, regulating river flows, protecting shorelines from erosion and storm surges, preventing salinisation of coastal aquifers and sustaining biodiversity; the direct competition between the two uses; and the call for regional coordination and possible global governance mechanisms).
• Stockholm Resilience Centre, "Use sand wisely, warns UN in new report", 12 May 2026 (the publication date and title of the report, its authorship by 27 international experts, the extraction of 50 billion tonnes a year faster than it replenishes, the dead and alive sand framing, and the report's conclusion with actionable policy measures and an assessment tool).
• GRID-Geneva, "Sand" (the programme's work on sand resources, the sand gap between extraction and replenishment, and the governance and measurement recommendations).
• Deltares, "Sand: wanted, both dead and alive" (the report launch and the competing demands on sand in its extracted and in situ states, from one of the contributing institutes).
• Geneva Environment Network, "Sand and Sustainability: An Essential Resource for Nature and Development, report launch" (the launch of the report in 2026 in response to the UN Environment Assembly resolution on strengthening international cooperation on the environmentally sound management of minerals and metals).