Experts urge caution on deep-sea mining, citing ecosystem risks and governance gaps

Lyanna Kash, communication officer with the International Science Council, opened a session at the UN Ocean Conference in Nice that focused on emerging ocean technologies and their governance, including deep-sea mining and marine carbon dioxide removal. "One that's of great concern is deep sea mining," said Dr. Elisha Aud Khalip, a lecturer in ecosystem governance and policy at the University of Melbourne.

Dr. Elisha Aud Khalip said the machinery proposed for seafloor mining would disturb metallic nodules and create sediment plumes, removing organisms from the seabed and dispersing material through the water column. "If you think about going along the seafloor with a lawn mower, [it] churns up the seafloor," she said, calling attention to plumes that can affect midwater and surface ecosystems as well as the seafloor.

Dr. Peter Oan, policy director at the Institute of Marine Research in Norway and a professor at the Geophysical Institute, University of Bergen, added that the deep ocean hosts poorly understood ecosystems that may perform unexpected planetary functions. He described recent research suggesting some seafloor rocks generate oxygen — a phenomenon the panel referred to as "dark oxygen" — and warned that removing such rocks could have cascading ecological effects.

Panelists emphasized that existing international law and instruments are fragmented. "We have UNCLOS and many sectoral agreements," Dr. Elisha said, naming the International Seabed Authority as the body with a mandate over seafloor minerals but noting overlap with fisheries, shipping and other treaties. She and Dr. Peter said that fragmentation complicates decisions about acceptable harm when impacts span different zones and sectors.

Both experts argued that unilateral actions by states or companies could undermine multilateral governance. "We've seen a company approaching the United States to try to apply for mining permits in international waters," Dr. Peter said, adding that such moves risk eroding accountability and the rule of multilateral agreements. Panelists noted legal avenues, including court challenges, but said litigation is not a substitute for stronger, preventative governance.

The panelists called for precautionary approaches, stronger cross-sectoral governance and greater inclusion of coastal communities and cultural values in decision-making. They said steps that would signal progress include a moratorium on commercial deep-sea mining and ambitious, scientifically informed content in the implementing agreement on marine biodiversity in areas beyond national jurisdiction. The session closed with thanks and a renewed call to integrate science into international instruments.

The session included no formal votes or binding decisions; panelists framed the discussion as expert advice and a call for multilateral action.