Prospects for Deep-Sea Mining

Increasing demand for raw materials and declining quality of resources on land is encouraging the search for alternatives in the oceans. Governments and commercial enterprises have received extensive licenses for exploration of marine minerals, and expectations are running high that a deep-sea mining industry is about to emerge. China, Japan, Korea, Russia, India, France, and Germany are actively exploring for manganese nodules that contain nickel, copper, and cobalt, with the aim of large-scale mining in the coming decades. Other countries (Papua New Guinea, Fiji, Tonga) have leased portions of their EEZs to companies searching for seafloor massive sulfides (SMS) that contain copper, zinc, silver and gold. The world's first commercial license for mining of SMS has been granted by the government of Papua New Guinea, and other countries, such as Japan, have made significant progress exploring SMS deposits in their waters. Some of the machines that will be used for mining of nodules and sulfides have been built already and are now being tested. Estimates of the abundance of nodules in the Central Pacific high-grade area are as high as 21 billion tonnes and, if recoverable, they could satisfy all current demand for manganese, nickel, cobalt and copper for decades and perhaps a century. SMS deposits represent a smaller resource, but they are characterized by much higher grades of metals, making them high-value targets. Recent estimates of the metal content of SMS deposits along the global mid-ocean ridges and in back-arc basins range from 10 to 30 million tonnes of contained copper and zinc, equivalent to one year of current world consumption. However, these estimates do not include vast numbers of SMS deposits that likely occur away from the ridges ‒ deposits that are partly or completely buried by sediment. Exploration for those hidden resources is just beginning and could dramatically change the global undersea resource potential. Despite these developments, it remains unclear whether the sizes and quality of the deposits would be sufficient to support a new mining industry. There is also continuing debate about sustainable approaches to exploiting the known resources and whether their development is worth the risk. Although there are both short- and longer term prospects for deep-sea mining, so far the tipping point in terms of economic, scientific, technological and regulatory advances has not been reached. The good news is that there is still time to do many of the things that science must do before any mining begins.