After water, sand is the raw material that the world consumes in the greatest quantity. It is no exaggeration to say that sand and coarser aggregates – the medium- to coarse-grained pebbles, gravel and rock fragments used in construction – are the building blocks of the modern world. When bound with cement, sand becomes concrete; when mixed with bitumen, it becomes asphalt; and when heated, it becomes glass. Without sand, we would have no highways, high-rises or high-speed trains.
Yet sand – which is used here as shorthand for sand and aggregates together – is a resource that is both abundant and finite. In global terms, it is abundant, especially when compared with many other raw materials, albeit often not available close to where it is needed. It is finite in that the rate at which we are using it far exceeds the natural rate at which it is being replenished by the weathering of rocks by wind and water.
Industrialization, population growth and urbanization have fuelled explosive growth in the demand for sand. Precise data on sand extraction are hard to come by and the lack of data compounds the challenge of managing the resource sustainably. However, the UN estimates that overall extraction could be in the region of 40 billion tonnes per year. That equates to 18 kilograms of sand each day for every person on the planet. Put another way, this quantity of material could build a wall of sand 27 metres wide and 27 metres high around the entire globe – every year.1
Herein lies the problem. Humanity's appetite for sand has become so huge that its extraction, trade and use are starting to have major impacts on our environment and communities – not to mention our politics.
Much of the increase in demand for sand has been driven by the remarkable economic growth of China, which now produces more cement and concrete – and hence uses more sand – than the rest of the world does put together. Since 2003, China has poured more concrete every three years than the United States did in the entire 20th century.2 Several other countries, such as India and Indonesia, have also entered a period of a dramatic increase in their sand consumption.
Another major use for sand is in land reclamation and port development. Eye-catching projects like Dubai’s Palm Jumeirah or World Island developments spring to mind, but major land reclamation projects around the world have also used hundreds of millions of tonnes of sand. Singapore has increased its land area by 20 per cent since the mid-1960s using large volumes of Indonesian and Malaysian marine sand. Extensive areas of Hong Kong, including its international airport at Chek Lap Kok, lie on reclaimed land.
Humans are now moving three times more sediment than all the rivers and glaciers of the world transport annually.3 The extraction of sand is a graphic example of how we have entered what many scientists are now calling 'the Anthropocene' – a new geological epoch in which human activity is the defining driver of environmental change on our planet.
Human activity is affecting the availability of sand in a number of other ways. The widespread damming of rivers is fundamentally interrupting the normal flow of sandy sediments that would otherwise be deposited in downstream delta areas and coastal zones. Meanwhile, a survey published in February 2019, noted that the climate change-induced melting of the ice sheet in Greenland is beginning to carry more and more sand into coastal zones around the island, potentially offering a valuable export commodity to a region facing significant disruptions to livelihoods as a result of global warming.4
Sand is a bulky, heavy material. It is cheap to extract and simple to process but expensive to transport. This has two consequences. First, sand mines are normally close to where the sand is needed. Rather than there being one global market for sand, the trade in it is made up of many smaller national and sub-national markets, each with its own demand and supply dynamics and challenges.
Second, historically at least, sand has been less intensively traded internationally than other commodities. Just five per cent of the trade in sand is across an international border. The majority of the trade is over short distances, such as a north-to-south hop across the Canadian-US border. That said, sometimes international trade in sand takes place over much longer distances. Dubai, for example, has so heavily depleted its own marine sand deposits through huge building projects that it has reportedly started to import construction sand from Australia.5
The international trade in sand was worth $4.5 billion in 2017 and it is growing at a rate of 5.5 per cent each year.6 The Global Aggregates Information Network, an industry body, estimates that total annual demand for sand and aggregates will rise to 60 billion tonnes by 2030.7 This has potentially significant implications for resource trade, transport-related emissions and resource security.
Typically, sand is dug from active sediment systems such as river banks, seashores or the sea bed or from fossil, non-active systems such as inland sand deposits. The speed and scale at which modern mechanical systems can extract sand has multiplied manifold over the past decades. While sand extraction used to be, and in some places still is, limited by how much can be moved by humans with shovels and wheelbarrows, modern dredging ships can hoover up to 100,000 tonnes of marine sand a day.
Sand extraction at that scale can have serious environmental impacts. Sand mining can kick up silt that smothers fisheries and affect local biodiversity and ecosystems.8 Meanwhile, the removal of large quantities of sand can accelerate the erosion of riverbanks and coastal areas, undermine bridges, change the flow of rivers, increase the risk of flooding and eliminate buffers against storm surges.9 10
Such impacts are particularly likely where there are no local regulations, when their enforcement is weak or absent, or when the underlying ecological, geological and hydrological dynamics of the extraction site are misunderstood or ignored. In most countries, sand mining is managed through national mining and environmental protection legislation with authority for regulation devolved to the local level. Legislation is frequently accompanied by non-binding guidelines to improve the environmental sustainability of the mining. This means that many small administrative units are responsible for enforcing regulations, which can hamper the overall management of the resource.11
The degree to which sand mining is regulated varies hugely from place to place. Often the effect of greater regulation in one area is to displace the extraction of sand elsewhere. For example, in 2000, Chinese authorities banned sand mining in the Yangtze River after extraction had caused the collapse of bridges and riverbanks.12 However, this led to the massive expansion of sand mining in Poyang lake, which is 300 miles up the Yangtze river from Shanghai. Poyang is China’s largest freshwater lake and an important stop-off site for millions of migratory birds including several endangered species.13 14 A 2014 study estimated that some 236 million cubic metres of sand are extracted from Poyang lake every year,15 which would make it lake the biggest sand mine on the planet, bigger than the three largest mines in the United States put together.
In future, sea level rise and more intense storm-induced waves associated with climate change may require the construction of many hundreds of kilometres of concrete sea walls to defend critical infrastructure. Although the overall material demands for effective adaptation under different scenarios is still unclear, it is safe to say that this would trigger a huge demand for sand.
As one example, there is growing appetite for sand for ‘beach nourishment’, a practice increasingly being employed in the Netherlands and the United Kingdom to replenish beaches that are important for property, tourism or ecological reasons. This form of integrated coastal-zone management deposits large quantities of marine sand onto vulnerable beaches as an effective, albeit temporary, way to stem coastal erosion. One expert speaking at a January 2019 conference at the British Geological Society estimated that the demand for sand for beach nourishment globally was likely to rise from 50 million cubic metres today (roughly 80 million tonnes) to 500 million cubic metres by 2050 (roughly 800 million tonnes).
Perhaps unsurprisingly, sand extraction has become a sensitive political issue within and across borders.
In several countries, sand extraction has become a criminal enterprise. The illegal extraction of river and coastal sand has been reported in as many as 70 countries.16 In India, ‘sand mafias’ have taken control of sand mines and there have even been reports of murders of local community members who complained.17 In Morocco, it is estimated that half of the country’s annual extraction – 10 million cubic metres – comes from illegal coastal sand mining. Illegal extraction has been so significant in some parts of northern Morocco that the resultant coastal erosion is threatening the buildings constructed with the stolen sand.
Sand extraction has also caused tensions between countries. Indonesia, Vietnam and Malaysia have imposed limits or temporary bans on the export of sand to Singapore which has been the world’s largest importer of sand over the past 20 years mostly for land reclamation.18 Much of this sand came from Indonesia where extraction has reportedly led to the disappearance of 24 sand islands and to increased political tensions between the two countries regarding their maritime border.19 Following a ban on the export of Malaysian sand in 1997, the cost of foreign sand in Singapore jumped to more than $200 per square metre from an average of $20 in the 1970s. This localised sand shortage intensified when Indonesia also banned the export of sand to Singapore in 2007, forcing Singapore to turn to other countries for sand.20
Population growth, urbanization and development will all boost the need for housing and infrastructure such as roads, bridges, hospitals, schools, airports and dams. There is a catch-22 in that huge quantities of sand will likely be needed to build the infrastructure for a sustainable future, but the very extraction of that sand may precipitate a range of serious environmental, social and political challenges. So what is to be done? What is clear is that there are answers – sand resources can be managed more sustainably and positive impacts achieved quickly.
As a priority, the first step is to better understand some of the dimensions of the sand sustainability challenge. How much sand will we need in future? Where will it come from? How will future trade flows of sand develop? What are the true costs of unsustainable sand use? And what kind of mechanisms can help move this sector towards being more sustainable?
The second is to encourage ways to reduce demand for sand, finding alternatives wherever feasible, and ensuring that primary sand is extracted in the most responsible and sustainable way possible. A 2019 UNEP publication summarizes practical ideas on each of these fronts. Reducing the demand for sand can be achieved through better land-use planning, avoiding overdesign, adopting ‘green’ approaches to infrastructure, using alternative materials where possible, and extending the life of existing buildings. Recycled and alternative materials such as demolished concrete and bottom ash from waste incineration can substitute for sand where it is still necessary. Sand substitution is underway in some countries. And, finally, there are best standards and practices that could better govern sand mining to mitigate the worst environmental and social costs.
The third step is to create the momentum among producers, consumers and regulators to improve the data and start introducing the kinds of solutions described above. This is an issue that warrants a much higher position on the political agenda. Part of the challenge of ensuring sustainability in this sector is its very ubiquity in that it takes place all across the world in a disparate way. Sand supply chains are complex and often invisible. Addressing such a fragmented sector requires a cross-sector approach to work out a vision that is consistent with best practice and that is commercially viable, but that also meets the needs of local communities. Ultimately, the extraction and trade of sand is becoming an enterprise of such scale and scope that it may require new global, as well as local, responses.