A novel method to reconstruct glacier volume changes from a measured length record is presented and tested for 13 glaciers in the Swiss Alps. The response of a glacier to changes in climate is modeled with a two-parameter dynamical system in the variables “length” and “volume”. Driven by a history of equilibrium line altitude (ELA), the model yields variations of glacier length and volume. A dynamically equivalent simple model (DESM) is determined for each glacier by matching modeled and measured length changes. The volume changes predicted with the DESM agree well with measurements for 12 glaciers, whereas agreement is poor for one glacier with topographic breaks in the terminus area. For all glaciers, which are located in different climate regions, the length and volume changes are reproduced with the same ELA history. This agreement shows that the macroscopic glacier response to the climate history is well correlated over a whole mountain range. Modeling the future evolution of the glaciers under a constant present-day climate reveals that fast-reacting glaciers are close to equilibrium, whereas length and volume of the large valley glaciers would be reduced during the next century by an amount similar to the volume lost during the last 150 years.