Fig. 2: Control of the warming threshold by snow accumulation.

Ice shelf average threshold temperature to reach MOA = 0.7, as a function of R-ERA5 average present-day (1979–2021) accumulation in mm w.e. per year. The colours represent R-ERA5 present-day surface melt rates (mm w.e. per year). Some specific ice shelves are highlighted, and only major ice shelves (>800 km²) are shown. The square boxes represent the average conditions presented in Fig. 1. The vertical error bars denote the uncertainty in T_T (dT_T, one standard deviation as described in the Methods), and the horizontal error bars indicate the uncertainty in accumulation (10% of the present-day mean accumulation³). The horizontal dashed lines represent the −9 and −5 °C isotherms commonly applied to AP ice shelves¹². The black line is a power-law fit of T_T as a function of accumulation, with the fit parameters, R² and root mean square error (RMSE) denoted in the figure text.