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Inside the high-tech effort to save the world’s dwindling sand reserves

Posted on February 7, 2024

Look closely at this interactive map of the world and squiggly pink lines are visible in almost every major saltwater body, from the Gulf of Mexico to the Bay of Bengal. The lines represent the movement of boats captured via a network of satellites and ground monitoring stations.

But these are not just any boats. Researchers suspect they are dredging sand from the ocean floor, an often poorly regulated practice that is destroying marine ecosystems and depleting global reserves of sand, one of the world’s most precious natural resources.

The interactive map is part of the Marine Sand Watch, the world’s first public data platform to monitor the dredging of sand and other sediments. “Sand dredging can have severe impacts on biodiversity and fisheries,” says Pascal Peduzzi, the director of GRID Geneva, an environmental information centre hosted by the United Nations Environment Programme (UNEP). “Until recently, dredging vessels were operating in the shadows. With our platform, we are making the invisible visible.”

This screenshot from the Marine Sand Watch shows suspected dredging off the east coast of the United States of America. Credit: UNEP

Launched by UNEP in September 2023, the Marine Sand Watch has uncovered what Peduzzi calls “worrying” trends. Among them, over the last decade, about 16 per cent of dredging has occurred in marine reserves designed to protect vulnerable plants and animals.

Dredging, dredging everywhere 

Sand is the world’s second-most-used commodity, after water. Marine sand is a staple in construction but the world’s reserves are being depleted at rates never before seen. UNEP estimates that between 4 billion and 8 billion tonnes of marine sand are being extracted every year. That is equivalent to 1 million lorries full a day.

“The path we are on now is simply not sustainable,” says Peduzzi.

Natural resource extraction more than tripled between 1970 and 2019, driven in large part by a massive increase in the mining of sand and other construction materials known as aggregates. The surge in resource extraction is fuelling climate change, species loss and water stress.

Later this month, government representatives, civil society groups, scientists and business leaders from around the world will gather in Nairobi, Kenya, for the sixth session of the UN Environment Assembly (UNEA-6), the world’s top decision-making body on the environment. Discussions are expected to focus on how science, data and digital technologies, like the Marine Sand Watch, can support the transition to more responsible mining and the sustainable use of minerals and metals.

In the aftermath of UNEA’s fifth session, UNEP conducted an intergovernmental consultation to identify priority issues related to mining and metals management. Countries have discussed establishing a broader Global Sand Observatory to further strengthen scientific, technical and policy knowledge.

An estimated 4 billion to 8 billion tonnes of marine sand are being extracted every year. That is equivalent to 1 million lorries full a day. Credit: Nur Photo via AFP/Thomas O’Neill

The Marine Sand Watch uses a type of short-range radio signal onboard larger boats to chart their movements. Advanced algorithms and artificial intelligence then analyze those motions, looking for the telltale signs of dredging. Those can include short back and forth movements.

During its first few months in operation, the Marine Sand Watch has detected poor dredging practices all around the world. Dredging hotspots were found off the coasts of Europe, North America, West Asia and East Asia. In several places, researchers believe sand was used to shore up beaches, ports and build artificial islands.

Between 2018 and 2022, up to one-sixth of dredging occurred in marine protected areas, zones that are supposed to be sanctuaries for underwater life.

“One of the major revelations of the last several months has been how common dredging is in protected areas,” says Peduzzi. “Frankly, that is a worrying development because dredging is so destructive and these areas are often ecologically very sensitive.”

Sand and gravel are vital parts of marine ecosystems. They form a bridge between land and sea, buffer coastlines against storms and protect coastal aquifers from salination. They also support countless plants and animals. Peduzzi says undersea life is often decimated by dredging vessels, which he compares to giant vacuum cleaners. “All the micro-organisms in the sand are crunched and nothing is left behind. If you take all the sand away to bare rock, nothing will recover.”

In 2022, the countries of the world signed the Global Biodiversity Framework, a landmark accord to protect and restore nature. One of the agreement’s targets includes safeguarding 30 per cent of the ocean. The Marine Sand Watch can help track just how protected those areas are, says Peduzzi.

Global standard needed 

The data gathered by the Marine Sand Watch goes beyond just tracking offshore dredging. It can also identify ports that specialize in the sand trade and estimate the total amount of sand extracted in a given country.

Peduzzi suspects most sand is dredged legally by companies operating in concessions handed out by governments. The platform can help countries ensure dredging companies are sticking to licensed areas that underwent environmental impact assessments. Peduzzi says nations can receive monitoring help from UNEP/GRID Geneva.

The Marine Sand Watch monitors about 60 per cent of all dredging vessels worldwide, with the goal of 100 per cent coverage.

UNEP’s Marine Sand Watch is tracking about 60 per cent of all dredging vessels worldwide. Credit: DPA Picture Alliance via AFP/Jens Buttner

There is no global standard for the extraction of sand. Peduzzi is hopeful the Marine Sand Watch will help change that and spur a discussion on best practices. The platform is also designed to help developing nations bolster their ability to monitor the environment.

“We need countries and the dredging sector to consider sand as a strategic material,” says Peduzzi. “We must swiftly engage in talks on how to create an international standard on marine dredging to minimize its environmental impacts.”

The sixth session of the United Nations Environment Assembly (UNEA-6) will take place from 26 February to 1 March, 2024 at the United Nations Environment Programme (UNEP) headquarters in Nairobi, Kenya. As the world’s highest decision-making body on the environment, UNEA aims to help restore harmony between humanity and nature, improving the lives of the world’s most vulnerable people. UNEA-6 will focus on how multilateralism can help tackle the triple planetary crisis of climate change, nature and biodiversity loss, and pollution and waste


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