Posted on January 9, 2025
Sand is among the most used natural resources on Earth, second only to water.
It’s an essential component of cell phones, concrete, glass, cosmetics, roads, and many other modern conveniences. For one billion people living in coastal areas around the world, these sand grains also defend against intense storms and sea level rise fueled by climate change.
Coastal beaches and dunes act like shock absorbers against extreme weather and provide a habitat for species like shorebirds and sea turtles to breed and for seabirds to raise their young. Sand is also key to land reclamation, the process of creating land through engineering where there once was water, and coastal armoring, whereby communities build infrastructure in an attempt to slow wave erosion along their shoreline.
Though plentiful in arid regions, most sand is not viable for commercial use or construction. Desert sand, whipped by years of wind, has smooth grains that prevent it from binding with most materials used in industrial applications. By contrast, sand extracted from rivers, lakes, or quarries is highly desirable for its irregular, angular grains.
Increased demand from the construction industry has led to sand scarcity in some regions of the world and shifted attention to sand sourced from marine and coastal environments, also known as ocean sand. This in turn has fueled rapid growth in the dredging industry, often at the expense of coastal communities and environmental health.
We’ve gathered three experts who study Earth’s surface, the ocean economy, and coastal communities to answer questions about the consequences of ocean sand extraction and its role in climate change adaptation around the world.
Our scholars include Jean-Baptiste Jouffray, a Wallenberg Postdoctoral Fellow at the Stanford Center for Ocean Solutions in the Woods Institute for the Environment. An expert on the industrialization of the ocean, Jouffray realized that few academics had considered the social and ecological consequences of ocean sand extraction. He led a global research team to produce a 2023 report that lays out the sustainability and equity challenges of sand extracted offshore and along the coast.
Additional expertise comes from Center for Ocean Solutions lead scientist Colette Wabnitz, who studies how social and ecological systems respond to change with a focus on small-scale fisheries, sustainable development, and ocean finance.
Wabnitz and Jouffray are joined by geologist Mathieu Lapôtre, an assistant professor of Earth and planetary sciences at the Stanford Doerr School of Sustainability, who studies the physics and physical processes that shape planetary surfaces. Most recently, his lab used AI to identify the formation and transport of individual sand grains, a potential tool for identifying sand that’s been mined illegally.
Where does sand come from?
Jouffray: In the tropics, island sand is produced by the disintegration of calcium carbonate shells and skeletons belonging to reef-building organisms—and hungry fish! Parrotfish in particular are major producers of island sand, digesting pieces of coral and turning them into sand-grade sediment when they excrete.
Lapôtre: Individual sand grains range in thickness from a single human hair to a standard pencil lead. This makes sand just the right size to be easily transported and deposited by rivers and wind. You’ll find sand throughout Earth’s landscapes—forming sandbars in rivers, collecting into windblown desert dunes, and accumulating under glaciers where ice grinds against bedrock.
Sand ultimately accumulates along the beach as a result of all of these processes. Rivers transport sand from uplands to deltas, which in turn redistribute sand along the coast aided by waves and winds. Coastal erosion can also generate sand locally, especially if coast-forming rocks are sandstones, which are ancient sand accumulations themselves.
The many colors—and shapes—of sand
Around the world and on other planets, sand takes a stunning variety of forms and colors:
- On the island of Hawai’i, Papakōlea Beach attracts visitors with its dark green sand. Hawai’ian volcanoes are composed of a green mineral known as olivine, which erodes over time and nourishes the island’s beaches.
- In the Ryukyu Islands of Japan, tiny glass-enclosed marine algae known as diatoms wash ashore. Their enchanting forms compose the sand that protects against shoreline erosion. When viewed under a microscope, the diatoms appear like tiny stars.
- On the island of Bermuda, tiny marine organisms known as foraminifera tint sand pink. When they die, their calcium carbonate shells sink and combine with white quartz to make the beaches seemingly blush.
- On Mars, the erosion of volcanic basalt creates black sand. Iron oxides are often concentrated into a fine layer of dust atop the sand, giving the planet its famous red hue and a dramatic red carpet welcome to visiting NASA robots.
“The origin of sand is really multifaceted. It’s much more than wind against rock,” said Wabnitz. “To know that beaches come from such different things means we can work toward ensuring that the mechanisms creating our beaches continue to be sustained.”
How does sand mining affect people and the environment?
Jouffray: Dredgers impact benthic habitats by dragging machinery along the seabed. They also create what are called turbidity plumes, huge clouds of sediment caused by vacuuming sand into the vessel’s storage hold and releasing excess seawater. These plumes can blanket and smother sensitive ecosystems like coral reefs or seagrass beds that require sunlight to survive.
Lapôtre: A landscape’s topography, wind, and water all dictate where sand accumulates. Sand mining disturbs that natural balance, and it can have ripple effects. One example of this is in Louisiana, where damming upstream of the Mississippi Delta reduced sediment transport to the coast. This, combined with sea level rise, results in significant land loss. In addition to reshaping the landscape, sand mining can disrupt entire ecosystems and release pollutants that are trapped in relatively old sand deposits.
Wabnitz: Sand mining affects the environment in important ways. I saw this first-hand working in Barbados on an impact assessment associated with a port expansion project. Dredging created sand plumes that threatened to smother a large reef nearby. To mitigate this, we excavated and relocated the corals. While the hope was for some of the system to recover, it is impossible to fully transplant an entire ecosystem and substantial losses are likely.
The people who bear the consequences of sand mining often have little or no opportunity to participate in decisions about whether or not sand mining takes place. When left out of these processes, communities can lose the very land upon which they live, their home, and the ecosystems they depend on for food, their livelihoods, their sense of place, their cultural heritage, and so much more.
I’m currently based in Vancouver, where First Nations and other groups have opposed a project that would double the size of Canada’s largest port through land reclamation. The environmental impacts are not clear, especially for culturally important species like orcas and salmon. The land itself holds deep cultural meaning for First Nations peoples.
How is sand connected to climate change impacts and adaptation?
Jouffray: Sand is essential to stabilize the shoreline in the face of climate change and sea level rise. Beach nourishment and coastal armoring have become common climate adaptation strategies. But the sand has to come from somewhere and it often happens at the expense of natural sand features, like nearby dunes or barrier islands. Dredging in one place usually accelerates coastal erosion elsewhere. In addition, the sand used to replenish or “nourish” eroded areas is just piled onto the beach, with no life in it. Sea turtles that nest on renourished beaches do poorly because their eggs cannot breathe in the densely packed grains.
Wabnitz: The vast majority of the Pacific region’s population resides within five kilometers of the coast and is at significant risk from sea level rise. Changing sea levels also changes which land is above water. Even though 39 leaders from the Alliance of Small Island States have issued a declaration that the boundaries of island states cannot be redrawn due to climate-change-related sea-level rise, losing sand or an island to climate change means losing homes, livelihoods, and cultural heritage.
What makes sand difficult to regulate, and what options exist to curb the negative consequences of sand dredged from the ocean?
Jouffray: One could argue that sand is paradigmatic of the Anthropocene, which refers to when human activity began to have a profound and unprecedented impact on the planet. It is everywhere around us. We need it for everything we do. Yet from a time-scale perspective, we are extracting it at a much faster rate than it can naturally replenish, and with severe human and environmental consequences.
We can learn lessons from other natural resources that span political boundaries, like fisheries. Similar to the seafood sector, sand mining has distinct small-scale or artisanal operations in addition to heavily industrialized dredging activities. Regulating both, disseminating best practice standards, and curbing illegal practices will be critical. Governments can also monitor dredging activity by tracking in near real time where vessels are and using satellite imagery to identify turbidity plumes or illegal activities.
Wabnitz: Regulatory mechanisms must account for the different entities affected by sand mining. This means recognizing both the environmental and the human consequences of sand extraction. Effective regulation means not just regulating big businesses but also, and especially, ensuring that smaller communities that depend on these sand systems in one way or another, have a seat at the table and a meaningful voice in the process.
At the international level, discourse about reparations for loss and damage from climate change often focuses on “land loss.” But land is sand, so sand needs to be a part of the broader loss and damage conversation.
