Summary : Ample evidence indicates the Arctic climate, cryosphere, and hydrological cycle is changing. Fluctuations in surface melt extent, mass balance, and freshwater runoff from the Greenland Ice Sheet (GrIS), and glaciers and ice caps (GIC) peripheral to the Ice Sheet, follows climate fluctuations, and response has already been observed and marked by glaciers retreating and thinning along the periphery. Most GIC are out of balance with the current climate, and farther from balance than previously believed. GIC peripheral to GrIS will likely lose at least 70% of its current area and 80% of its volume even in the absence of further climate changes. For GrIS, a high-resolution (5-km) model was used to simulate surface melt extent and trends before ...