Ashby, A 2026, 'Environmental impacts of deep sea mining: a comprehensive review of 
regulatory frameworks and ecological risks', in AB Fourie, G Boggs, J Heyes & M Tibbett (eds), Mine Closure 2026: Proceedings of the 19th International Conference on Mine Closure, Australian Centre for Geomechanics, Perth, pp. 1-18, https://doi.org/10.36487/ACG_repo/2615_159
(https://papers.acg.uwa.edu.au/p/2615_159_Ashby/)
Abstract: Deep sea mining (DSM) is an emerging frontier in global resource development, driven by demand for critical minerals needed for the energy transition. The International Seabed Authority (ISA) has issued 31 exploration contracts covering more than 1.3 million km² of sea floor; however, exploitation regulations remain unresolved and the governance capacity of contracted states is a growing concern. This rapid review evaluates key environmental impact pathways, including habitat destruction, biodiversity loss, sediment plume generation, disruption of oceanic carbon sequestration, impacts on pelagic ecosystems and fisheries-dependent communities and long-term ecosystem alteration. Evidence synthesised indicates DSM poses substantial and potentially irreversible risks to marine ecosystems, with recovery timescales potentially extending from centuries to millennia. Restoration is scientifically unproven and economically prohibitive, with the only peer-reviewed deep sea restoration cost estimate reaching up to USD75 million per hectare. Post-impact restoration cannot be treated as a credible mitigation or offset mechanism. Many states holding exploration contracts exhibit limited regulatory capacity, weak treaty compliance and elevated institutional risk. The findings underscore the urgent need for precautionary governance frameworks, strengthened environmental baseline monitoring and enhanced international oversight before commercial-scale DSM is authorised.