An international research team led by the University of Birmingham has identified a previously undocumented atmospheric process occurring in the Arctic that generates particles capable of forming clouds. The findings, released in August in Nature Geoscience, are based on measurements collected during expeditions in spring and summer 2022 around Greenland and the Davis Strait aboard the Royal Research Ship Discovery.
The particle-forming mechanism takes place in the marginal ice zone, where retreating sea ice meets open ocean. In this narrow region, naturally occurring iodine, sulfur, and organic compounds released from marine life and chemical reactions driven by sunlight combine to create atmospheric particles. Researchers observed a fifty-fold increase in cloud-forming particles within a single day, with concentrations in some instances rising from approximately 50 to 1,500 particles per cubic centimeter. The team detected the phenomenon on more than 80 percent of sunny days, indicating the process is frequently active in this part of the Arctic.
The research also identified a previously unknown class of atmospheric compounds called iodine-containing oxygenated organic molecules (I-OOMs). These newly discovered molecules appear to facilitate the growth of nascent particles until they become large enough to influence cloud formation. According to co-author Dr. James Brean, the findings represent the first real-world validation of an atmospheric chemistry mechanism involving iodine oxoacids and sulfuric acid that had previously only been demonstrated in laboratory conditions.
As Arctic temperatures rise and sea ice continues to retreat, the marginal ice zone expands, potentially increasing the geographic area where this particle-forming process occurs. The implications for cloud cover could be significant, as altered cloud patterns affect how much solar energy is reflected back into space and retained in the atmosphere. Current climate models do not account for this mechanism, meaning its effects on Arctic climate projections are not yet represented. Researchers are working to incorporate the process into climate modeling systems to improve predictions of Arctic climate change dynamics.
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