Almost half of all natural world heritage sites are slowly being degraded, and experts have a clear suspect: humans. A study based on the Human Footprint Index—which evaluates agriculture, infrastructure, population density, and other factors—identifies more than 100 of 229 sites that are suffering from human activities, reports Smithsonian. "The world would never accept the Acropolis being knocked down, nor a couple of pyramids being flattened for housing estates or roads, yet, right now, across our planet, we are letting many of our natural world heritage sites be fundamentally altered," the study author says in a release. The Guardian notes that many sites suffering damage are home to endangered species or those that can’t be found anywhere else.
Losses were seen on every continent, but North America alone has accounted for 57% of forest loss globally since 1993, with pine beetles seen as the main problem. Overall, however, sites in Asia fared the worst. Some notable specifics close to home: The Waterton Glacier International Peace Park on the US-Canada border has lost 23% of its forested area, Yellowstone 10%, and the Grand Canyon 6%. This "is alarming and must be addressed," says lead author James Allan from the University of Queensland. The study authors urge UNESCO to institute conservation measures before the damage becomes irreparable. (Australia wanted to log one of its heritage sites.)