Differential Decline in Terrestrial Water Storage Across Major Permafrost-Dominated Arctic River Basins During the Rapid Warming Period From 1981 to 2020

Terrestrial water storage (TWS) in northern high-latitude regions is strongly influenced by climate warming and the resulting permafrost thaw. However, it is not yet fully understood how different permafrost types constrain TWS changes during the rapid warming period. In this study, we focused on the six major Arctic river basins (Ob', Yenisei, Lena, Kolyma, Yukon, and Mackenzie), which are characterized by widespread permafrost, and employed three TWS products derived from remote sensing observations, land surface models, and reanalysis data sets to quantify changes in TWS anomalies during the rapid warming period (1981–2020). Statistical analyses revealed differential TWS declines across all permafrost types, with the most significant decline observed in the discontinuous permafrost regions at −3.05 mm/year, compared to in the continuous permafrost regions (−0.78 mm/year) and in the sporadic permafrost regions (−2.45 mm/year). Correlation analyses further indicated a pronounced negative relationship between permafrost active layer thickness (ALT) and TWS, especially in discontinuous permafrost regions, where a 1-cm increase in ALT corresponded to a TWS decrease of up to 4.4-mm. These findings highlight the significant impact of permafrost thawing accelerated by climate warming on TWS changes in permafrost-dominated Arctic regions, with important implications for regional hydrology, carbon feedback, and ecosystem stability in the pan-Arctic. Our results underscore the necessity of incorporating permafrost-specific processes into hydrological models and climate assessments, thereby enhancing projections of water resource a4vailability and environmental changes in northern high-latitude regions.