Mountains are far more than rocks. They also confer various natural benefits—for example, about half of the world’s drinking water filters through their high-elevation forests, plants, and soils.Now, a new, first-of-its kind study, in the journal Nature, shows how these mountain ecosystems around the globe may be threatened by climate change.Rising temperatures over the next decades appear likely to “decouple” key nutrient cycles in mountain soils and plants, an international team of sixteen scientists reports. Their study suggests that this is expected to disrupt the function of mountaintop ecosystems, as plant communities above and at treeline are thrown into turmoil faster than trees can migrate uphill in a warmer world.