On the Greenland Ice Sheet, lakes that form on the surface during summer can rapidly drain through cracks in the ice, sending large amounts of water to the base of the ice sheet within hours. If the drainage overwhelms the system beneath the ice, it can cause the ice above to lift slightly, forming a “blister.” These blisters temporarily speed up the movement of the surrounding ice and then gradually disappear as the water drains away.

Although satellite and field observations have detected these blister-related changes, current models of subglacial water flow don’t include the formation or decay of blisters. As a result, they can’t fully capture how water pressure and ice movement interact after a lake drains.

To address this gap, we developed a new model that combines blister dynamics with an existing subglacial water flow model. We connect this to an ice-flow model focused on a region of western Greenland. Our simulations show how blisters behave differently in summer and winter and help explain observed surface motion. This improved model can help scientists better interpret ice sheet observations following lake drainages and make more accurate predictions about Greenland’s contribution to sea-level rise as the climate warms.