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Around 9040 glaciers have been reported in India, covering nearly 18 528 km² in the Indus, Ganges, and Brahmaputra basins (Sangewar et al. 2009; Sharma et al. 2013). Any changes in a glacier can affect river run‐off and the water availability in the Himalayan rivers (Indus, Ganges, and Brahmaputra) and agricultural practices in India. The annual rate of glacial shrinkage is reported to be nearly 0.2–0.7% in the Indian Himalayan region for 11 river basins during the period 1960–2004 with a mean extent of 0.32–1.40 km² (Kulkarni et al. 2011; Bolch et al. 2012). Ramanathan (2011) reported the mass balance of Chhota Shigri glacier (15.7 km²), located in the Chandra River basin of Himachal Pradesh, showed a net loss of about 1000 m from 2002–2009. The flow diagram demonstrating the impact of climate change on glaciers is depicted in Figure 1.3.

Figure 1.1 Impact of climate change on water resources.

Figure 1.2 Decade‐wise average rainfall annual data of India.

(Source: Envi Stats India 2018; https://data.gov.in/keywords/annual‐rainfall.)

In India, climate change is expected to affect Himalayan rivers (Ganges and Brahmaputra) due to the faster rate of melting of Himalayan glaciers. Himalayan glaciers are known as the “Water Tower of Asia,” a major source of water in all major Asian rivers (Shiva 2009). As per the Intergovernmental Panel on Climate Change (IPCC), these glaciers are receding faster than any other part of the world (IPCC 2007). The Gangotri glacier (source of the river Ganga), receded 20–23 miles/year, whereas other glaciers can retreat more than 30 miles/year as a result of rising temperatures (Shiva 2009). If the conditions continue, glaciers will melt quicker and no glaciers will be left to supply water for the entire year, then rivers like Brahmaputra and Ganges will become seasonal rivers. In the monsoon season, the combination of the heavy melting of glaciers and intense heavy rainfall for fewer days may create a flash flood‐like situation. On the other hand, reduced rainfall in the rest of the year may lead to drought in some regions. Chevaturi et al. (2016) illustrated the climate change impact on the northern region of Ladakh. The Ladakh area is unique due to its location in high altitude, dry desert with cold temperatures, and water flows to the mountains. Research showed a warming trend with reduced seasonal precipitation, making it highly sensitive to temperature changes.

Figure 1.3 The flow diagram of the impact of climate change on glaciers.

(Source: Pandey and Venkataraman 2012.)