The majority of glaciers are currently retreating globally but had been in an advanced position for several hundred years during the so-called Little Ice Age (LIA). During this period, the lateral accumulation of rock and debris created impressive moraine walls. Between these LIA moraines and the actual terminus position is the glacier forefield, which is growing as glaciers retreat. Whereas the forefields are constantly changing (e.g. due to the transport of sediment and rock, lake formation and growth, plant colonization), the outer boundary marked by the moraines changed little and has widely been used to reconstruct maximum LIA extents and volume for numerous glaciers around the world. Together with field and satellite measurements, a detailed time series of glacier fluctuations since the LIA has been obtained for hundreds of glaciers that indicate some regional and glacier-specific variability, but also robust global trends of shrinkage and volume loss. Overall, the kilometre-scale retreat and upward shift of glacier termini by several 100 m since the end of the LIA confirm a global temperature increase by about one degree. As most glaciers have not yet adjusted their geometry to current climatic conditions, they will further shrink while forefields will continue to grow.