The Arctic is experiencing rapid environmental changes due to climate change. One of the critical indicators of these changes is water storage change, affected by factors, including the snow and ice melt, permafrost thaw, and changes in precipitation patterns. Understanding these changes is crucial for assessing the impact of climate change on the region and its implications for the global environment.

Remote sensing (RS) has proven effective for monitoring water storage change in the Arctic. Existing RS-based studies have provided valuable insights into the region's hydrologic changes. However, they have focused on examining few major watersheds or had limited time frames. Consequently, there remains a significant knowledge gap regarding the spatial variation of water storage change and the underlying drivers across the pan-Arctic watersheds and (2) the status of water storage changes in the most recent decade, during which climate change has intensified.

To fill this gap, we investigated the water storage changes over 20 major watersheds and 120 sub-watersheds in the pan-Arctic region from 2002 to 2022. Our study utilized multi-source RS data, such as GRACE for water equivalent, SSM/I for snow water equivalent, AMSR-E for vegetation and soil water content, MODIS for evapotranspiration, CMAP for precipitation, and RADR (remote sensing and observation integrated data) for stream flow. Based on the water balance equation, we examined the key drivers of water storage change across the pan-Arctic.

Our findings indicated a decreasing of water storage in most major watersheds, with significant decreases observed in Greenland, and the Lena and Yenisei watersheds due to increased snow melt and water discharge. Conversely, several coastal watersheds, such as Kathanga and Indrigarka, had an increase in water storage due to enhanced water supply from uplands. The Mackenzie watershed displayed the largest spatial variation, with decreased water availability and increased snow melt and stream flow in the upland sub-watersheds, while lowland watersheds were dominantly influenced by snow melt. This study highlights the variability of water storage change in the Arctic from a broader range of watersheds and an extended period, which helped gain deeper insights into the drivers of these changes across this critical region.