Glaciers are key contributors to sea-level rise and are critical water resources that supply fresh water to hundreds of millions of people around the world. It is therefore of paramount importance to accurately simulate the future evolution of these precious ice bodies. Despite recent progress in modelling the global evolution of glaciers, existing simulations suffer from vast uncertainties related to (i) model input, (ii) a simplified representation of glacier processes, and (iii) an important mismatch between the timescales over which models are calibrated (multi-annual to decadal) and those over which the future glacier projections occur (century timescale). ICE³ will revolutionise the regional- to global-scale modelling of glaciers, by (i) strongly reducing uncertainties in model input through innovative inversion of climatic information, (ii) developing new approaches to model glacier processes in 3D, and (iii) for the first time simulating past glacier evolution globally over centennial time scales with an ice-dynamic model. These improvements will culminate in new global glacier evolution projections under a range of future emission scenarios, which will in turn inform the next generation of sea-level rise and water availability projections. While redefining the landscape of large-scale glacier modelling, ICE³ will also ensure that the novelties it produces are incorporated in climate change impact models to guide policymakers and practitioners in adapting to a changing environment.