Obsolete submarine cables abandoned on the ocean floor represent an invisible form of pollution as substantial as it is invasive.
Submarine Cables: No International Regulation on Their Handling
The figures are enough to make one shudder: more than 3.5 million kilometers of telecommunications cables have been laid on the seabed since the 19th century to carry 99% of global internet and telephone traffic. Today, two-thirds of these infrastructures are out of service, abandoned on the ocean floor. The recent extraction of 45% of the famous TAT-8 transatlantic cable stands as an exception to this trend.
In the absence of binding international regulations, the removal of these endless metal cables depends solely on economic profitability. Private companies are beginning to extract certain cables solely to resell the metals they contain. But they limit themselves to international waters where no environmental impact assessment is required. In the open ocean, the common practice is to cut, push aside, or pile the old cables to make room for new ones, at the expense of any sensible cleanup logic.
Ecological and Public Health Risks Along the Shoreline
But it is near the coast, in the heart of the areas richest in biodiversity, that these wastes pose the heaviest problems. The study conducted by the Blue Coast Marine Park near Marseille shows that abandoned cables drift with the swell, crush the Posidonia oceanica seagrass beds, and deteriorate by releasing heavy metals such as lead near bathing areas. Although French law now requires funding for dismantling before laying any new cable, the technical complexity and the legal ambiguities surrounding the ownership of some old infrastructures still hinder cleanup.
The theoretical 25-year lifespan of these cables is widely shortened by economic imperatives: many are abandoned after only seven to ten years of use due to the arrival of more powerful technologies. As hyperscale data centers and artificial intelligence drive the ongoing deployment of high-speed networks, this massive and little-known underwater pollution must be addressed.
