Sustained decrease in inland East Antarctic surface mass balance between 2005 and 2020

Accurate observations of surface mass balance are pivotal for assessing the Antarctic Ice Sheet mass balance and its link to climate dynamics. Studying regional changes in surface mass balance is challenging due to limited on-site observations and the susceptibility of measurements from snow pits and ice cores to localized disturbances. Satellite data and short-term localized measurements suggest no significant changes or a possible increase in surface mass balance across the East Antarctic Ice Sheet in recent decades, but these findings lack large-scale validation. Here we use observations from mass balance stakes to show a significant negative surface mass balance trend along the inland transect from Zhongshan Station to the Antarctic Ice Sheet summit (Dome A) during the period 2005–2020. The mean surface mass balance trend for the inland section over the 15-year period is −2.01 ± 0.37 kg m⁻² yr^–2, indicating a 35.5% decrease. This decrease is probably linked to enhanced zonal winds in the upper atmosphere and a deepened low-pressure system in the southern Indian Ocean. The former weakens meridional air transport to Antarctica, while the latter strengthens offshore winds over the study area, reducing onshore water vapour transport. These findings can be used to evaluate and improve regional climate models and refine estimates of contemporary Antarctic mass balance trends.