Toxic algae turned a frozen lake green

Climate change and pollution are making rare winter cyanobacteria blooms more common. Breakthroughs, discoveries, and DIY tips sent six days a week. In the Czech Republic, a frozen lake's emerald green ice is giving biologists an unprecedented opportunity to study a strange--and ominous--natural phenomenon. At the end of 2025, researchers at Czech Academy of Sciences traveled to Lake Lipno in South Bohemia to collect and examine samples from a rare cyanobacteria bloom in the dead of winter. Their findings could help better understand a problem that threatens both local marine life and nearby human populations.