Influence of seasonal sea-ice loss on Arctic precipitation 18O: a GCM-based analysis of monthly data

Rapid Arctic warming and sea-ice loss have intensified the Arctic hydrological cycle, increasing local evaporation and precipitation. Stable water isotopes as environmental tracers can provide useful insights into the Arctic hydrological cycle. However, the paucity of isotopic observations in the Arctic has limited our understanding of the hydrological changes. Here, we use an isotope -enabled atmospheric general circulation model (IsoGSM) combined with the Global Network of Isotopes in Precipitation (GNIP) observations to investi-gate the relationship between sea-ice changes and Arctic precipitation 818O (818Op) to reveal the relative influence of local air temperature and evapora-tion on Arctic summer and winter 818Op. We find that the Arctic 818Op is neg-atively correlated with sea-ice concentration but positively with air temperature. Sea-ice loss leads to enriched Arctic 818Op through enhanced local evaporation and warming, but the relative importance of these pro-cesses varies between seasons. During summer, both local evaporation and warming contribute equally to 818Op changes. In contrast, winter 818O is pre-dominantly driven by air temperature. This work improves our understand-ing of how Arctic precipitation isotopes respond to sea-ice changes and has implications for the Arctic hydrological cycle and palaeotemperature reconstructions.