Deep in northern Alaska’s Brooks Range, a network of pristine rivers snakes its way through 600 miles of tundra and glacial valleys. While the waters normally run a cool, crystal blue, scientists have noticed an alarming trend: Dozens of the range’s rivers have taken on an eerie shade of muddled orange. The reason for the change in color was as alarming as its hue: The waters are rusting. As permafrost melts, long-stored acids and metals—including iron—are released into rivers, where they interact with oxygen, turning the water from clear blue…
