The ‘third pole’ is the planet’s largest reservoir of ice and snow after the Arctic and Antarctic. It encompasses the Himalaya–Hindu Kush mountain ranges and the Tibetan Plateau. Meltwater feeds ten great rivers, including the Indus, Brahmaputra, Ganges, Yellow and Yangtze, on which almost one-fifth of the world’s population depends.
Climate change threatens this vast frozen reservoir For the past 50 years, glaciers in the Himalayas and Tibetan Plateau have been shrinking.https://www.nature.com/articles/d41586-018-07838-4 The meltwater of the third pole feeds a lot of rivers if the third pole is nearly gone, then it can't feed rivers sufficiently. Basically, due to the warming, glaciers melt more in the summer then they grow in the winter. The third pole: https://en.wikipedia.org/wiki/Third_Pole