Antarctica’s rapidly growing tourist industry is leaving a measurable pollution footprint, according to a peer-reviewed study published on Wednesday in the journal Nature Sustainability. Researchers who traversed roughly 2,000 kilometres of the Antarctic Peninsula found concentrations of heavy metals such as chromium, nickel, copper, zinc and lead in surface snow that are about ten times higher than readings taken 40 years ago. The contamination tracks a boom in visitors to one of the world’s most fragile ecosystems. Tourist numbers have jumped from around 20,000 a year in the early 2000s to about 120,000 last season, data from the International Association of Antarctica Tour Operators show. Lead author Raúl Cordero of the University of Groningen said the soot and metal particles released by ships, aircraft and ground vehicles darken snow surfaces, with a single visitor estimated to accelerate the melt of roughly 100 tonnes of snow. Scientific programmes are also implicated: because researchers spend far longer periods on the continent than cruise passengers, their per-stay impact can be up to ten times greater, the paper notes. While environmental rules already bar the use of heavy fuel oil and encourage hybrid propulsion, the authors call for faster adoption of low-carbon technologies and stricter limits on human presence to prevent further ice loss in a region that is already shedding an average 135 billion tonnes of ice each year.