"Third Pole" Water Imbalances Examined

A new study has identified a water imbalance in the Himalayas. The Hindu Kush–Karakoram–Himalayan system, or the “Third Pole” is a reservoir of fresh water that serves nearly 2 billion people downstream.

The Tibetan Plateau in the Himalayas, often dubbed the Asian Water Tower, stores the largest amount of frozen water on the planet after the North and South poles. An international team of scientists has now identified imbalances caused by an increase in temperatures over the last 4 decades.

Since 1980, the region has been warming at a rate of 0.42C per decade, a rate which is twice the global average. Despite an increase in annual precipitation, since 2000, the glacier mass has decreased by 340 Gt (gigatons).

The faster rate of melting ice has caused levels in water basins to change. In basins with no output connections water levels have increased. On the contrary, in basins that are connected to rivers that supply downstream populations, water levels have decreased.

Professor Tandong Yao, the lead researcher of the study whose findings were published in ”Nature Reviews - Earth & Environment”, said: “Such imbalance is expected to pose a great challenge to the supply-demand balancing of water resources in downstream regions.”

While global warming is expected to exacerbate these imbalances, the researchers suggest that some water bodies like the Yellow and the Yangtze Rivers will see their levels rise as others such as the Indus and Amu Darya River basins will see hem decrease.

More accurate predictions of these impacts, however, depend on further, more detailed studies with improved water level monitoring tools.