New research from the University of St Andrews reveals that carbon dioxide released from neutralizing acid mine drainage in metal mining may be far larger than conventional carbon footprints account for. The study, published in Environmental Science and Technology, examined 82 mines in southeastern Spain and found that emissions from acid mine drainage neutralization already rival the entire carbon footprint of copper production in that region. These emissions can continue for centuries or millennia after mining stops, as exposed metal sulfides slowly react with water. This finding matters for the green transition because demand for mined metals is rising for solar panels, wind turbines, and grid infrastructure. If these hidden emissions are not measured and addressed, the true climate cost of metal production will be significantly understated. The researchers call for new remediation methods that reduce CO2 release during acid mine drainage treatment. For carbon markets and climate policy, this means mining carbon footprints need a major update. Ignoring acid mine drainage emissions could lead to inaccurate accounting and missed opportunities for emission reductions in the mining sector.
