Influence of Seasonal Sea Ice Loss on Arctic Precipitation δ18O: A GCM-Based Analysis of Monthly Data

Rapid Arctic warming and sea ice loss have led to an intensification of the Arctic hydrological cycle, which is characterized by increased 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 investigate the relationship between sea ice changes and Arctic precipitation d¹⁸O (d¹⁸O_p), and reveal the relative influence of local air temperature and evaporation on Arctic summer and winter d¹⁸O_p. We find that the Arctic d¹⁸O_p is negatively correlated with sea ice concentration, but positively with air temperature. Sea ice loss leads to enriched Arctic d¹⁸O_p through enhanced local evaporation and warming, but the relative importance of these processes varies between seasons. During summer, both local evaporation and warming contribute equally to d¹⁸O_p changes. In contrast, winter δ¹⁸O is predominantly driven by air temperature. This work improves our understanding of how Arctic precipitation isotopes respond to sea ice changes and has implications for the Arctic hydrological cycle and paleotemperature reconstructions.