Arctic ice edge found to generate cloud-forming particles missing from climate models

A newly documented atmospheric chemistry pathway operating at the Arctic ice edge can boost the number of cloud condensation nuclei dramatically, researchers report. The study, published in Nature Geoscience, shows that sunlight converts iodine, dimethylsulfide and organic vapours released by the ocean, sea ice and coastal algae into particles that multiply up to fifty times within a single day. Field campaigns on the Royal Research Ship Discovery in spring and summer 2022 recorded particle spikes from roughly 50 to 1,500 per cubic centimetre in the marginal ice zone near Greenland and the Davis Strait.

The team also identified a novel class of iodine-containing oxygenated organic molecules that help these particles grow to cloud-relevant sizes. As Arctic sea ice continues to melt, the ice-edge region widens, potentially extending the reach of this particle-forming process. Current climate models lack this mechanism, prompting the authors to work on integrating it to improve projections of Arctic cloud cover and warming. Funding for the research came from the Natural Environment Research Council.