The change in mass balance due to a change in a climatic variable such as air temperature or precipitation. Sensitivities to temperature and precipitation are often expressed as changes in response to a 1 K warming or a 10% precipitation increase, resulting in a negative sensitivity to temperature and a positive sensitivity to precipitation. Sensitivities are generally derived from mass-balance modelling, that is, from the difference in mass balance between model runs with and without climate perturbation, but they have also been estimated from mass-balance and climate observations. Mass balance does not vary linearly with the climate in general. That is, d: B/d: T and d: B/d: P are not constant, but they may be assumed constant as a good approximation for small changes of the climatic variable. The 'dynamic' mass-balance sensitivity changes as the extent and area-altitude distribution of the glacier or glacierized region evolve. In contrast, the 'static' sensitivity neglects these geometric changes, although it may still vary with, for example, components of the surface energy balance.