A new study published in *Nature* reveals that bioaerosols from terrestrial ecosystems play a crucial role in Arctic ice formation. The research, conducted during the MR22-06C Arctic research cruise, found that fungal spores, specifically identified as highly fluorescent particles (HFPs), are a significant component of ice-nucleating particles (INPs) that are active at temperatures above -15°C. These spores originate from boreal forests and tundra ecosystems in Alaska and Canada and are transported over the Arctic Ocean, influencing cloud microphysics.