Home South pole ice An imbalance of the meltwaters of the 3rd Earth pole

An imbalance of the meltwaters of the 3rd Earth pole


Earth’s 3rd Pole, aka the Asian Water Tower, is the region that encompasses the Hindu Kush Himalayan mountain range and the Tibetan Plateau. This area is the third largest reservoir of snow and ice in the world after the Arctic and Antarctica. It provides water for 25% of the Earth’s population. The region has warmed at rates well above northern hemisphere warming rates and the global average. Annual and seasonal temperatures have increased more in higher elevation areas across the third pole. Glaciers are retreating, permafrost is degrading, and snow cover days are decreasing at the third pole. Map via Weforum.org. Legend via TPE.

The 3rd pole of the Earth is melting

The Hindu Kush Himalayan mountain range and the Tibetan plateau are sometimes referred to as the 3rd pole of the Earth. The region includes the largest reservoir of frozen water after the North and South Poles of the Earth. This so called Asian water tower supplies much of Asia – 25% of the Earth’s population, or about 2 billion people – with fresh water.

Scientists have known for some time that Earth’s 3rd pole is melting and flooding will become a problem, likely between 2030 (or before) and 2050, when annual runoff from glaciers peaks. Then water shortages will begin. This month (June 7, 2022) – while acknowledging that the region’s future “remains highly uncertain” – scientists published a new study suggesting that an imbalance in the way meltwater flows will cause those in the north of the region to have a greater supply of water, in the short term, while those in the south will face more immediate and greater shortages.

The scientists are associated with TPE (Third Pôle Environnement). TPE has set up an observation network which includes 51 sites for monitoring the evolution of glacier thickness, 35 on the mass balance of glaciers, 16 on the evolution of permafrost, 6 on the evolution of snow cover as well as 16 hydrological and meteorological data collection. Initiated in 2009 by three scientists, TPE is part of UNESCO and is called:

…an international program for the interdisciplinary study of the relationships between water, ice, air, ecology and humanity in the Third Pole region and beyond.

The scientists published the new study in the peer-reviewed journal Nature reviews Earth and environment June 7, 2022.

A section of the Earth with a large bright round white spot over a mountainous area: the Earth's 3rd pole.
3rd pole of the Earth. Graphics via TPE.

The 3rd pole of glacier runoff is not balanced

As the newspaper explains:

From 1980 to 2018, the Asian water tower warming was 0.42°C [about .8 degrees F] per decade, twice the global average rate.

They told their study:

… synthesize[d] observational evidence and model projections that describe an imbalance in the Asian water tower caused by the accelerated transformation of ice and snow into liquid water. This phase change is associated with a south-north disparity due to the spatio-temporal interaction between the westerly winds and the Indian monsoon.

In other words, although global warming itself caused the general melting, the westerlies (prevailing winds) and the Indian monsoon created an imbalance. The researchers said that as the transformation of ice and snow into liquid water accelerates, the amount of liquid water in the north will (temporarily) increase while the supply in the south will decrease. This imbalance will alleviate water scarcity in areas such as the Yellow and Yangtze river basins in the short term. On the other hand, they said, it will increase scarcity in the Indus and Amu Darya basins.

Yao Tandong, lead author and co-chair of Third Pole Environment, said:

Such an imbalance is expected to pose a great challenge to the balance between supply and demand of water resources in downstream regions.

The future of the Asian water tower

These scientists therefore believe that it is possible that populations north of the Tibetan plateau will have a greater water supply for longer, while populations in the south will experience greater water demand more quickly. Scientists predict that the greatest demand for water will be in the southern Indus basin. The demand is largely due to the irrigation of agricultural land. In fact, 90% of the water usage in this region goes to irrigation to help feed the region’s large population. The Indus and Ganges Brahmaputra basins are home to the largest irrigated agricultural area in the world.

The researchers said the north-south disparity will increase – in the coming decades of this century – as the climate warms. Piao Shilong from Peking University and the Chinese Academy of Sciences said:

Concrete policies for the sustainable management of water resources are greatly needed in this region.

The researchers also said more studies would help provide more information to people in the region so they can anticipate changes. Lonnie Thompson of Ohio State University and co-chair of Third Pole Environment said:

We need more accurate predictions of future water supply to assess mitigation and adaptation strategies for the region.

Three of the scientists’ future goals are comprehensive monitoring stations, advanced modeling and sustainable water management.

A graph showing the glaciers, with the runoff between them, and a legend:
This image is a screenshot from a video titled NASA Tracks Future of Asia’s Glaciers.

Bottom line: An imbalance in runoff from melting glaciers at Earth’s 3rd pole — aka the Asian water tower — may mean more water supplies in the north and less in the south.

Source: The imbalance of the Asian water tower


Read more: Hundreds of millions of South Asians at risk from melting glaciers