Recent observations show an accelerated ice loss of the Greenland ice sheet during the past few decades which makes it a major contributor to sea-level rise. The SeaRISE experiments have shown the sensitivity of current ice sheet models to external forcing to gain insight into the potential future contribution to sea level from the Greenland ice sheet. Although the model results show a similar trend of mass loss, the model responses are not always homogeneous. This may an effect of different employed e.g. numerics, approximation to the Stokes flow, spatial resolution, and initialization methods (spin-up). Here, we use the thermomechanical coupled Ice Sheet System model (ISSM) to re-run the SeaRISE experiments using different spin-up strategies. The spatial resolution is kept constant and the higer-order approximation to the Stokes flow is employed. As a first approach we use an inverse method and data assimilation for the basal friction to match present day condition. In contrast to this simulation, we also perform spin-ups with climatic forcing and different parameters for a non-linear sliding law. The simulation results are compared in order to examine the difference of mass loss.