Arctic sea-ice loss is emblematic of an amplified Arctic water cycle and has critical feedback
implications for global climate. Stable isotopes (δ18O, δ2H, d-excess) are valuable tracers
for constraining water cycle and climate processes through space and time. Yet, the paucity
of well-resolved Arctic isotope data preclude an empirically derived understanding of the
hydrologic changes occurring today, in the deep (geologic) past, and in the future. To
address this knowledge gap, the Pan-Arctic Precipitation Isotope Network (PAPIN) was …

Mellat et al. Pan-Arctic Summer Rainfall Isotopic Traits slopes (> 0.75/◦ C) were observed at
continental sites, while statistically significant temperature relations were generally absent at
coastal stations. Model outputs indicate that 68% of the summer precipitating air masses
were transported into the Arctic from mid-latitudes and were characterized by relatively high
δ18O values. Yet 32% of precipitation events, characterized by lower δ18O and high d-
excess values, derived from northerly air masses transported from the Arctic Ocean and/or …