What natural resources did you consume today?

Well, there’s water of course, and food. No doubt some oil products. You could probably think of many other things to add to your list.

But how much sand did you use today? The answer may come as a surprise because it turns out that, after water, sand and gravel are the second most-used natural resource on our planet

We use sand mainly to make concrete for buildings and to build roads. Sand and gravel are used for road base and laying train tracks. Sand is mixed into asphalt and it is used as fill for construction. Globally, our annual sand and gravel consumption is estimated to be around 53 billion tonnes. That's equal to around 7.5 tonnes per year (~20 kg/day) for every person on earth.

Most sand comes from the erosion of mountains by rivers and glaciers. Scientists have estimated that all the rivers on Earth deliver around 12.6 billion tonnes of sediment to the sea each year. In other words, humans are currently using sand at a rate that is four times faster than it is being produced by nature, which of course is not sustainable. It is time to pull our collective heads out of the sand and recognize the problem of our consumption of sand for what it really is.

As our cities have grown and land-based sources of sand and gravel are used up, people are turning to the sea for new supplies. Mining of sand from beaches is becoming an issue in many countries. Taking too much sand from the beach results in coastal erosion and can negatively affect tourism. Many European countries have been mining sand from offshore sand banks for several decades. The practice is expanding rapidly in other parts of the world but figures are difficult to find and the quantities of sand mined offshore are unknown.

What is known is that marine sand mining is often very destructive. The act of dredging the seabed kills the plants and animals living in the mined area and the plume of disturbed mud can blanket the seabed and smother sea life in surrounding areas. The damaged sites can take anywhere from several years to decades to fully recover. There are also cases of corruption and illegal activities associated with the sand mining industry, adding a socio-economic dimension.

We need to reduce our global “sand mining footprint” and lower our rate of consumption of sand to sustainable levels. This can be achieved by optimising use of existing buildings (don't keep building new structures if there is unused space). Recycled building material can be a substitute for sand and gravel and it is possible to use up to 40% of incinerator ash in place of sand in many cases.

Some desert sand can be used if mixed with other material and we need to pay a correct price for, and taxes on, sand so that regulators have the resources they need to ensure environmental guidelines are followed during the extraction and site rehabilitation. Finally, we need better knowledge of sandy environments and their dependent ecosystems in order to make the best, wisest use of our remaining sand and gravel resources.

UN Environment highlighted the issue this week by hosting an event on the topic as part of a meeting of the Joint Group of Experts on the Scientific Aspects of Marine Protection (GESAMP) meeting in Nairobi, Kenya. International experts were invited to give presentations on the issue of sand mining.

One outcome of the discussion is that the group of experts will give further consideration to the issue of coastal erosion and extent to which it is exacerbated by sand mining. A related issue of release of carbon from sediments that are disturbed during offshore sand mining activities will also be considered.