According to a Sept. 8 paper published in the proceedings of the National Academy of Sciences, an iconic Arctic watershed in Alaska's Brooks Range has recently turned a dark, murky orange color, alarming scientists throughout California and Alaska. "This is what acid mine drainage looks like," Tim Lyons, a biogeochemist at UC Riverside, told the university in a September 2025 article. "But here, there's no mine. The permafrost is thawing and changing the chemistry of the landscape." According to the research paper, authors believe that permafrost - soil, rock or sediment that's been frozen for at least two years - is thawing, exposing sulfide minerals and delivering iron and other potentially toxic metals to the remote Alaskan wilderness.