Kinematic wave modeling is used to evaluate possible responses of the Greenland ice sheet to changes in its surface mass balance. In the approach followed here the reference state is defined based on measured velocity and discharge flux along the central flow line of Petermann Glacier in the northwest, and perturbations on this state are considered. The results indicate that significant rates of thickness change can occur immediately after the prescribed change in surface mass balance but adjustments in flow rapidly diminish these rates to a few centimeters per year at most. Full adjustment of the ice sheet requires times of the order of 1000 years. The instability mechanism known as the Jakobshavn Effect is discussed and, based on observational evidence as well as results from prior modeling studies, it is concluded that this is an unlikely mechanism for destabilizing major drainage basins of the Greenland ice sheet. ¿ 2001 American Geophysical Union