Extended Data Fig. 4: Correlations between retreat and local environmental factors.

A matrix of correlation coefficients (r) compares relationships between glacier mass change owing to calving, the range of seasonal mass variability owing to calving, the timing of seasonal maximum mass, bed slope and surface slope within 5 km of the glacier terminus, bed elevation, thickness, velocity and ice flux at the terminus, mean surface runoff from each catchment, oceanographic sill depth and mean ocean-temperature anomalies measured within 10 km of each glacier terminus, compared for 95 glaciers for which observations of all variables are available. The top row of the mass variability correlation matrix distils the results shown in Fig. 4, and negative values indicate that glaciers tend to lose mass where the dependent variable is higher. To account for relationships between mass and glacier terminus thickness and width, we normalize mass values by glacier terminus face area, providing a measure of effective length variability that reveals that seasonal variability is the strongest simple predictor of long-term retreat.