This undated handout photo obtained on July 21, 2026, from Luke Bridgestock of the University of St Andrews shows a view of the Tinto River, with pollution from acid mine drainage, in the Iberian Pyrite Belt in southwest Spain. New research published in Environmental Science and Technology on July 22, 2026, shows the carbon footprint linked to metal mining could be 10 times greater than previously thought, with major implications for net-zero ambitions. Metal mining is highly energy-intensive, and conventional estimates for its carbon footprint attribute most of its emissions to heavy equipment on-site, as well as diesel transport required to haul ore away. Luke Bridgestock of the University of St Andrews and colleagues instead looked at a process called acid mine drainage, a common side effect of mining that, despite being well-understood, had never properly been quantified before this study. The team focused on the Iberian Pyrite Belt in Spain, a copper-mining region with 82 active or historic mines going back to 1875 that generates more acid mine drainage than anywhere else in the world. (Photo by Luke Bridgestock / University of St Andrews / AFP via Getty Images) / RESTRICTED TO EDITORIAL USE - MANDATORY CREDIT "AFP PHOTO / University of St Andrews / Luke Bridgestock" - HANDOUT - NO MARKETING NO ADVERTISING CAMPAIGNS - DISTRIBUTED AS A SERVICE TO CLIENTS / TO GO WITH AFP STORY by Issam AHMED, "Metal mining's carbon footprint could be 10 times greater than thought: study"