Marine Sugars Play Key Role in Ice Nuclei Formation Over Southern Oceans

Recent research conducted by an international team led by the Leibniz Institute for Tropospheric Research (TROPOS) has revealed that polysaccharides produced by marine microorganisms significantly contribute to the formation of ice nuclei in clouds above the Southern Ocean. This finding, published in the journal Environmental Science & Technology on July 17, 2025, highlights the critical role of biological agents in cloud formation, particularly in remote marine environments like the Southern Hemisphere.

The study indicates that at temperatures between -15 to -16 degrees Celsius, polysaccharides derived from oceanic microorganisms are likely the predominant ice nuclei over large areas of the Southern Ocean. These compounds enter the atmosphere through sea spray and evaporation processes, facilitating the freezing of water droplets and thus influencing cloud and precipitation dynamics. According to Dr. Roland Schrödner, a researcher at TROPOS, “Our simulations show that these marine-derived polysaccharides contribute more to ice formation than the mineral dust typically assumed to be the primary source in climate models.”

Historically, climate models have struggled to accurately replicate cloud behavior over the Southern Ocean. This discrepancy arises from a lack of understanding regarding the sources and nature of ice nucleating particles (INPs) in clean atmospheric conditions. The current research addresses this gap by firmly establishing that biological sources, particularly polysaccharides from marine organisms, are integral to the ice nucleation process.

Dr. Sebastian Zeppenfeld, also from TROPOS, noted, “During our previous expeditions, we observed elevated glucose levels in Arctic samples, prompting the hypothesis that polysaccharides could play a critical role in ice nuclei formation.” The study further explored the nucleation capabilities of various marine polysaccharides, including those derived from fungi and protists, setting a foundation for future investigations into the interactions between marine biology and atmospheric processes.

The implications of these findings extend beyond academic interest; they highlight the importance of biological components in the global climate system. As climate change initiatives reduce anthropogenic emissions, the role of natural aerosols, such as those from marine microorganisms, may become increasingly significant in influencing cloud microphysics and, by extension, climate patterns.

Future research efforts are set to build on these findings, with upcoming field studies planned under the “HALO-South” mission from July to October 2025, which aims to further investigate the interactions of clouds, aerosols, and radiation in the Southern Ocean. The research will involve ground-based measurements and aerial observations to deepen our understanding of the intricate relationships between oceanic biology and atmospheric conditions.

The study not only redefines our understanding of ice nucleation in remote marine environments but also emphasizes the interconnectedness of ecological and atmospheric systems. This research marks a significant advancement in climate science, particularly in understanding the mechanisms driving precipitation formation in some of the planet's most pristine regions.