The balance between the accumulation and ablation of ice in a glacier. Its components are accumulation, ablation, and iceberg calving. A glacier that is not in balance with the ambient climate loses/gains mass and thereby raises/lowers global sea level (IAMU, 2006–7). The flow of solid ice governs the dynamical response of the glacier to a change in its mass budget. Machguth et al. (2007) Geophys. Res. Abs. 9, 06249 compare the output of three distributed mass-balance models of differing complexity.