How does a glacier retreat?

Answer 1

Correctly speaking a glacial tongue does not "retreat",
but MELTS DOWN.

As the picture illustrates the rock marked with an arrow is steadily moving downhill - at the same time the glacier front seems to "retreat".

As the lower part of a glacier is dominated by ablation and melting the position of the front is stable as long as the amount of ice flowing down the glacier is as high as the amount melted at the tongue. If more ice melts at the tongue than is brought there by iceflow, the front "moves" backward - although the direction of the iceflow remains the same!
http://www.slf.ch/staff/ariane_walz/IGMK/pages/about_glaciers_retreat.htm

Answer 2

Glaciers retreat because they do not get enough snow in their neves........The neve is a basin at the top of the glacier that builds up with snow that is then compacted by weight into ice. This due to the shape of the valley and gravity are forced down the glacier.....when there is lots of snow the galcier moves forward....this has a delay effect of years!!! and if there is little snow over the winter then the glacier will retreat....Franz Josef Glacier is one of the fastest moving ones in the world, when I worked there it was moving nearly 2 mters per day FORWARD, it has been retreating again (but I have now heard its forwards agian!!)...but I think overall its retrating....This is a useful glacier in loking at weather patterns.

Answer 3

It sort of fades away. A glacier is a river that is frozen. With sufficient warmth, at some point along the glacier's watershed, it warms enough to become water, and you see the water flowing below that level. If conditions get even warmer, the glacier's water/ice point moves further up the watershed, which appears as a retreat in extent.

Answer 4

It just melts into the background

Answer 5

it melts from the lower end backwards