Of course glaciers are on the edge of melting! Unlike your freezer, there is no refrigeration engine in the glacier, and it only exists in a place where it's cold enough. Hence, on the edge of it, it's only marginally cold enough. It gets a bit warmer, the Glacier recedes. Where mountaintops are held up by the strengh of this ice, any shrinkage of it will make stuff slide. This is not a catastrophe of course, unless you happen to live in the path of it.
Same thing with rising sea level, if you live on some atoll with only a few elevation above sea level, marginal effects will make your life pretty uncomfortable. Same thing if lots of people live in some semi-arid place and just about sustain their water consumption by drawing water from lakes and rivers all around: if it rains just a little less, the lakes dry up.