A corrie is an armchair-shaped hollow found on the side of a mountain. This is where a glacier, a massive river of flowing ice, forms. Glaciers form the corrie when more and more snow piles up.

As the glaciers of South America retreat, the supply of freshwater is dwindling and its quality is getting worse.

Komal’s morning view was of jagged, forbidding mountains, the rush of the river dozens of metres below the family home on the ...