An Increase in the Antarctic Surface Mass Balance during the Past Three Centuries, Dampening Global Sea Level Rise

Antarctic surface mass balance (SMB) is a direct regulator of global sea level changes, but quantification of its long-term evolution at the ice sheet scale is challenging. Here, we combine for the first time a recently complied dataset of ice core records with the outputs of five different reanalysis products and two regional climate models to produce a rec-onciled 310-yr reconstruction of spatially and temporally complete SMB over the Antarctic Ice Sheet (AIS). Despite greatly variable signs and magnitudes of reconstructed SMB trends in the different regions, a significant positive trend (3.6 +/- 0.8 Gt yr-1 decade-1) is observed for SMB over the entire AIS during the past 300 years, with a larger increase rate since 1801. The increased SMB cumulatively dampened global sea level rise by -14 mm between 1901 and 2010, which did not account for the ice sheet dynamical imbalance. The first and second modes of empirical orthogonal function analysis (EOF1 and EOF2) capture 38.0% and 24.6% of the total variability in reconstructed SMB, respectively. EOF1 consists of an east-west dipole of SMB changes over West Antarctica, primarily driven by Southern Annular Mode (SAM) variability. EOF2 represents a strong signal over the whole Antarctic Peninsula and coastal West Antarctica, which is not associated with SAM, but with El Nino-Southern Oscillation (ENSO) at the decadal scale.

Automated summary

The Antarctic surface mass balance (SMB) is an important factor in regulating global sea level changes. By combining ice core records, reanalysis products, and climate models, this study provides a comprehensive reconstruction of the spatial and temporal complete SMB over the Antarctic Ice Sheet (AIS) for the past 310 years. The results show a significant positive trend in SMB over the entire AIS, with a larger increase rate since 1801. This increased SMB has cumulatively dampened global sea level rise, although the dynamics of the ice sheet were not considered.