Assessing the global metal mining pollution risk to the marine environment

The extraction of metal ores has quadrupled over the last 55 years to support population growth and economic activity. Metal mining is currently estimated to affect 23 million people worldwide by contaminating the environment with toxic levels of naturally low abundance elements (e.g., lead, zinc, copper, and arsenic). The number of people exposed to potentially toxic mine waste is likely to grow during the 21st Century due to a higher demand for metals and greater hazards associated with climate change. A recent assessment found that long-term discharge of mine waste has significantly impacted freshwater systems, but no study has estimated the scale of mining-related contamination on the marine environment, limiting mitigation capabilities. Here, we synthesise the first global database of near-shore metal mine sites and stable and failed tailing storage facilities and compare their locations to worst-case scenario projections of climate, precipitation, and extreme sea-level rise by the year 2100 to fill this critical knowledge gap. We find 4094 active mines, 28,563 inactive mines, 11,472 tailing storage facilities, and 12 tailing dam failures that could contaminate up to 292,805 km of coastline. We identify six hotspots where overlapping climate hazards are expected to pose the greatest risk: North and South America, northern Europe, the Mediterranean, East Asia, and Australia. Our perspective underscores the need for enhanced ocean- and satellite-based observations to constrain the attenuation of mine-related metals to the coast, enabling governments and the mining industry to prioritise regions for monitoring and mitigation, supported by legally binding policy.