What is awesome here is the depths of ignorance displayed by the people on this board. It is not the interior ice that is melting and causing the speed up of the glaciers, it is the ends of the glaciers where they meet the ocean. Melting back past the grounding line. But it is useless to try to explain to room temperature IQ's what that means.
So your saying NASA is wrong. They are saying there are rivers and lakes under the ice, which I would suppose are running towards the ocean, possibly causing the ice to slide in that direction as it is probably the direction of least resistance. I dont think melting around the edges would cause warmer rivers and lakes in the interior of the ice.
Plumes are long live phenomena, so why is the ice streams speeding up now, and why is the ice eroding from the sea terminus? The water in the ocean is warmer, and that would not come from a land based plume. Because the water in moving, not static.