‘Glaciers feeding eastern rivers of Indus basin retreating faster,’ says top glaciologist Anil V Kulkarni

Kulkarni said studies carried out by him and his colleagues have shown that the glaciers feeding the Ravi, Sutlej and Beas rivers, located at a lower altitude, are retreating at a faster rate in comparison to the glaciers in Pakistan, located at high altitudes in the Karakoram range. As a result, the amount of glacial meltwater is projected to be much higher than the previous decades till the middle of the century, which would be followed by a significant reduction in water availability, he said.

“The glaciers located on the eastern side are located at a relatively lower altitude, and they are losing mass at a higher rate, thus retreating faster. As you go higher, in the Karakoram mountain ranges, glaciers are not losing mass, they are relatively stable. In the scientific community, it is called the Karakoram anomaly,” said Kulkarni, a scientist at the Divecha Centre for Climate Change, Indian Institute of Science, Bengaluru.

Scientific studies have attributed this anomaly to myriad factors such as cooler summer temperatures, more snowfall during winters, and more mass of rock and debris, which insulate the glaciers.

Under the IWT, signed in September 1960, all waters of the Indus basin’s eastern rivers — Satluj, Beas and Ravi — are available to India for unrestricted use. Pakistan has rights over the western rivers — Indus, Jhelum and Chenab — and being upstream of its neighbour, it can only use waters of these rivers for non-consumptive use, such as to produce hydropower, navigation, flood protection and control, and fishing.

Kulkarni pointed out that the glacier-stored water — the water held by a mass of glaciers — is not uniform across India and Pakistan. He said the impact of global warming on these glaciers will also not be uniform. The glaciers located in Pakistan have a greater store of water compared to glaciers in India, he said.

“When this treaty was written, nobody had an idea about glacier covers and snow cover. This data started coming from the beginning of this century, when satellite sensors produced good data. Hence, the treaty was written without a better understanding of the basin, and that was a fundamental lacuna,” said Kulkarni.

“Now, we are aware of the changes in the stream run-off and the original proportion of water allotted can get disturbed. There will be a change in precipitation. There is no clarity on how it will change, but there is clarity on how temperatures and glacier water is going to change in the future. These factors will affect water availability in these regions. So definitely, the treaty needs a relook so that regional allocation is maintained,” he said.