Tiny algae darken the surface of glaciers and thus accelerate their melting. This is the case, for example, on the Greenland Ice Sheet, which plays an important role in our climate and is already melting increasingly fast due to global warming. A study by the Max Planck Institute for Marine Microbiology in Bremen, Germany, and the University of Aarhus, Denmark, now shows that the ice algae grow extremely efficiently, despite the fact that there are hardly any nutrients available to them on the ice.