Arctic Ozone Anomalies and the Associated UV Radiation Increase in the 21st Century in Simulations with CCM SOCOLv3

Two major factors influence the expected recovery of the ozone layer: a decline in ozone-depleting substances (ODSs) due to implementation of the Montreal Protocol and stratospheric cooling due to increasing greenhouse gas (GHG) concentration. We investigate the largest spring Arctic ozone anomalies revealed in three ensemble calculations of the chemistry–climate model (CCM) SOCOLv3 under moderate (SSP2-4.5) and severe (SSP5-8.5) scenarios of GHG growth, accounting for the expected decline in ODS concentrations over 2015–2099. During the first half of the 21st century, the coldest winters could still produce Arctic total ozone content (TOC) anomalies comparable with the record spring 2020 values, despite the overall recovery of the ozone layer by mid-century. In March and April, TOC may occasionally drop below 220 Dobson Units. According to estimates from the Moscow State University (MSU) radiation model, the lowest TOC values under cloudless midday conditions could increase surface UV radiation by a factor of 1.5–2, reaching a UV index of 5–6 (and up to ~8 in April)—levels requiring sun protection measures.