Annual balance after above-median winter gains fell in two nine-glacier European panels from 1980-1999 to 2004-2023; loss frequency changes were uncertain

We tested whether winters with mass gain above each glacier's 1980-1999 median still prevented annual mass loss in 2004-2023. We used the same nine Central European and nine Scandinavian glaciers from WGMS version 2026-02-10. The primary changes in annual loss frequency were +16.9 and +24.7 percentage points. The conditional 95% three-year block intervals were -2.1 to +39.8 and -2.0 to +46.5 points. Thus neither primary test showed a clear frequency change. Mean annual balance after these winters fell by 0.548 m water equivalent in Central Europe and 0.528 m in Scandinavia. The pointwise intervals were -0.934 to -0.195 and -0.894 to -0.076 m. These continuous balance outcomes are secondary. Similar-winter pairs also had lower later annual balances. The results describe selected long records. They do not measure the causal effect of snow or regional water supply. Survey changes, coupled errors, selection, fixed historical thresholds and only 20 years per period limit inference. The package preserves code, the 694-row panel, source hashes, primary bootstrap draws, checks and a figure.

glacier mass balance · winter accumulation · seasonal balance · WGMS · fixed panel · null result · block bootstrap