Asked by MessiHe
A great question! When we look at most glaciers and ice sheets, the velocity is higher at the marine-terminating snout. So what is going on?
There are several factors at play here. Firstly, if the glacier is floating at its terminus, then there is zero friction or basal drag to slow down the ice velocity. The only resistice forces are the longitudinal forces within the ice. Where the ice floats, it will stretch, thin, and accelerate until it calves off icebergs. This is why the ice streams in Antarctica flow so much faster than their tributary glaciers.
Further up-stream, where the ice is grounded, the ice will accelerate due to the longitudinal extensional stresses within the ice.
If the ice surface steepens, the glacier flow will accelerate as well.