Sand extraction is one of the most understudied global challenges of the 21st century [1]. Over the past two decades, the global demand for sand has tripled, reaching a staggering 50 billion metric tons annually, making it the second most traded natural resource worldwide [2]. This unsustainable exploitation, often poorly regulated and plagued by rampant illegal extraction, has led to what many describe as a looming tragedy of the commons [3]. The lack of international guidelines or regulations may stem from the absence of comprehensive global studies on the impact of sand mining on marine ecosystems. The depletion of sand reserves is not just an economic concern; it poses significant threats to ecosystem integrity, biodiversity, and human well-being [4]. Sand mining activities place an enormous burden on coastal and marine ecosystems through physical disturbances like erosion, sedimentation, and habitat destruction. Dredging, a common method of extracting sand, removes the top layer of sediment from the seafloor, leaving behind deep depressions, sometimes up to 5 meters or more. This process strips the seabed of its substratum and associated organisms, effectively "sterilizing" the area by eliminating the microorganisms that sustain local marine life [5]. Such disturbances displace benthic fauna and flora, putting marine and coastal biodiversity at risk. This can result in the loss of vital fishing grounds threatening the lives and livelihoods of fishers around the world [6]. Sensitive environments, such as coral reefs and seagrass meadows, are particularly vulnerable. Dredging for sand can smother coral with sediment, reducing the light they need for photosynthesis, and can even result in the direct removal or burial of entire reef sections [7]. The impacts of sand removal are also not confined to the immediate area and can extend to surrounding regions through turbid plumes - huge dust clouds under water - as well as sediment resuspension. Sand dredging also heightens the vulnerability of coastal areas to sea level rise, erosion, flooding, and storm surges. This is because sand acts as a crucial buffer, protecting coastlines. For example, extensive sand mining in Sri Lanka is now recognized as a factor that worsened the devastation caused by the 2004 Indian Ocean tsunami, the deadliest tsunami in recorded history [10]. Additionally, unsuitable materials, such as rocks or debris, are often dumped back into the sea, sometimes far from where they were removed from the seafloor, disrupting new ecosystems. 2 Sand is crucial for both ecosystem function and human development, yet existing studies have focused on specific regions and have not provided a comprehensive analysis of the true scale and impact of sand dredging and extraction. It is also unclear how much of global dredging is driven by sand mining versus other activities, such as port expansions or deepening channels. This lack of understanding leaves us blind to potentially negative impacts of dredging and mining. Just as transparency and monitoring have been instrumental in reducing deforestation by holding governments and companies accountable, a similar approach is urgently needed for sand mining [8]. Although several countries have established regulatory frameworks for marine sand extraction specifically, practices vary significantly across the globe. In many regions, differing laws apply offshore, and while the seabed within the Exclusive Economic Zone (EEZ) is typically stateowned, numerous countries have yet to implement comprehensive legislation or effective monitoring programs for the extraction and management of their marine sand resources. The United Nations Environment Program (UNEP), as mandated by its member states, is tasked with enhancing scientific, technical, and policy knowledge related to sand, and supporting global policies and actions for its environmentally responsible extraction and use. UNEP calls for the establishment of an international standard for marine sand mining as well as the need to ‘map, monitor and report sand resources for transparent, science-based and data-driven decisionmaking’, emphasizing the timely need to map global sand dredging and extraction activities [9]. At the Environmental Markets Lab (emLab), we propose collaborating with UNEP and Global Fishing Watch (GFW) to address this gap. Our proposed project aims to assess the footprint of marine sand dredging and mining on a global scale and estimate quantities of sand being removed to identify potential hot spots of mining activity. Specifically, we will: 1) characterize the scale of marine sand mining globally by developing a map of ocean-based sand dredging related to sand mining, and 2) identify potential environmental and socioeconomic impacts. By mapping the global footprint of sand dredging, we can bring much-needed visibility to its effects, enabling more informed decision-making, and greater accountability. Only with this level of transparency can we fully grasp the true extent and costs of sand dredging, including sand mining and transport, and take the necessary steps to mitigate its effects.

We propose to develop the world’s first comprehensive map of marine sand dredging and sand mining as the first step towards understanding the magnitude and nature of the conservation threat it may pose. Outlined below is our proposed research approach.