What glacier zone has net ice loss because ablation exceeds accumulation?

The glacier zone with net ice loss because ablation exceeds accumulation is the ablation zone.

Usually found at lower elevations, this part of a glacier loses mass through melting, sublimation, evaporation, wind erosion, avalanches, or calving if the glacier reaches water. On many land-terminating glaciers, surface melting is the dominant process; on marine-terminating glaciers, calving may be especially important.

The ablation zone is separated from the higher accumulation zone by the equilibrium line. Above that line, snowfall and other gains exceed losses over the balance year. Below it, the annual balance is negative, so exposed glacier ice commonly appears after seasonal snow disappears.

The zone is not always bare or uniformly melting. Rock debris can increase melting when thin by absorbing sunlight, but thick debris can insulate the ice. Rising temperatures can also push the equilibrium line upward, expanding the ablation zone and contributing to glacier retreat.