ON CHORABARI GLACIER, India - This is how a glacier retreats. At nearly 13,000 feet above sea level, in the shadow of a sharp Himalayan peak, a wall of black ice oozes in the sunshine. A tumbling stone breaks the silence of the mountains, or water gurgles under the ground, a sign that the glacier is melting from inside. Where it empties out - scientists call it the snout - a noisy, frothy stream rushes down to meet the river Ganges. D.P. Dobhal, a glaciologist who has spent the last three years climbing and poking the Chorabari glacier, stands at the edge of the snout and points ahead. Three years ago, the snout was roughly 90 feet farther away. On a map drawn in 1962, it was plotted 860 feet from here. Mr. Dobhal marked the spot with a Stonehenge-like pile of rocks. Mr. Dobhal’s steep and solitary quest - to measure the changes in the glacier’s size and volume - points to a looming worldwide concern, with particularly serious repercussions for India and its neighbors. The thousands of glaciers studded across 1,500 miles of the Himalayas make up the savings account of South Asia’s water supply, […]