This topic has spilled into Unthreaded.
The one comment that I would be inclined to make on this is that, if people are depending on water from glacier retreat in tropical and temperate settings, then it seems to me that their water supply would be equally diminished by glacier stabilization or advance, not just by glacier disappearance. What proportion of the water delivered to (say) India is from the annual precipitation-melt cycle and what proportion from “mined” meltwater from glacier retreat? Or other places?
During the Laurentide glacier retreat from North America, apparently the Ottawa River was equivalent in size to the Amazon.