Substantial contribution of iodine to Arctic ozone destruction

New observations made during the Multidisciplinary drifting Observatory for the Study of Arctic Climate (MOSAiC) expedition show that iodine chemistry plays a major role in controlling tropospheric ozone over the Arctic. Using a chemical model, it is shown that the reactions between iodine and ozone are the second highest contributor to surface ozone loss, after the loss initiated by ozone photolysis, and ahead of bromine. This changes the decades-old paradigm on the drivers of Arctic photochemical ozone loss, which was hitherto attributed mainly to bromine chemistry. These observations also suggest that the atmospheric increase in iodine loading due to enhanced anthropogenic ozone-induced ocean iodine emissions, as well as the thinning and shrinking of Arctic sea-ice expected in the near future, will probably lead to increases in iodine emissions. This study shows that iodine chemistry needs to be included in models studying the ozone budget in the Arctic.

Reference: Benavent, N., Mahajan, A.S., Li, Q., et al. (2022). Substantial contribution of iodine to Arctic ozone destruction. Nature Geoscience. https://doi.org/10.1038/s41561-022-01018-w.