Life in ice seems to be a paradox, but already the Greek knew about algae growing in snow. In the mediaeval, especially in alpine regions, intensively pigmented snow algae caused anxieties amongst the catholic inhabitants who supposed that the reddish coverage of snow was not of organic origin, but God´s blood.
Nowadays, the acceptance of living forms inside ice like ice covers of lakes, glaciers or large snow areas is broad. Tricky adaptations of microorganisms show up to sustain the microbial metabolism at subzero temperatures. Surprisingly, life in ice is not solely survival, but based on evolutional adjustment to harsh living conditions the cells are optimized to these conditions. Several research expeditions to the Antarctic and the Arctic, respectively, proof the ecological relevance of microbes living in hostile habitats by unanticipated high concentrations of carbon production which is made available to higher life forms. Since both alpine and polar regions are not immediate affected by human influence, they are a mirror of cultural changes and abuse, respectively, and therefore valuable indicators for long-term changes.