A frozen lake in Czechia turned an ominous green color, a warning sign of ecological changes due to a warming climate. The rare sight of the green ice is most likely due to weeks of sunshine, calm weather, and weak winds, according to the researchers. In Czechia, Lake Lipno has been experiencing longer algae seasons that can sometimes continue into December. The case of Lake Lipno is the most well-documented one worldwide and shows that regular cyanobacteria blooms can exhibit strange behavior under atypical circumstances. The researchers, however, predict the sight of green ice may become more common in the future as the effects of climate change continue to alter ecosystems.