Climatic controls on interannual mass balance of global glaciers and ice caps

Global glacier mass balance exhibits pronounced interannual variability, yet the climatic drivers of this variability and its influence on inferred long-term trends remain poorly constrained. Here we use the Gravity Recovery and Climate Experiment (GRACE) mission and GRACE Follow-On (GRACE-FO) satellite gravimetry of global glaciers and ice caps over 2002–2024, applying Independent Component Analysis to detrended mass anomalies, to show that nearly 70% of global interannual glacier-mass variability is explained by two statistically independent modes, indicating a low-dimensional structure in the global signal. The leading mode is strongly correlated with the cumulative North Atlantic Oscillation (\(\:{NAO}_{\sum\:}\)) index, while the second mode tracks the cumulative Pacific Decadal Oscillation (\(\:{PDO}_{\sum\:}\)) index, revealing the long memory of glacier mass balance under sustained atmospheric circulation regimes. Accounting for variability associated with these cumulative climate modes yields a markedly more linear residual glacier-mass-balance record, demonstrating that internal climate variability can mask or distort apparent trends in GRACE-era observations. Our framework provides an observation-based constraint on how internal climate modes modulate high-latitude glacier change and on the interpretation of short satellite records in detection, attribution and sea-level projections. These results highlight vulnerable Arctic glacier regions where internal variability most strongly distorts apparent trends in mass balance.