The Himalayas, sometimes called ‘the roof of the world’, are the most extensive and rugged high altitude areas on Earth with over a hundred mountains exceeding 7,200 metres in elevation and the largest areas covered by glaciers and permafrost outside the polar regions. Himalayan glaciers are also referred to as Earth's ‘third pole" and Asia’s ‘water towers’ because they supply fresh water to communities throughout South Asia. Roughly 210 million people live in the region, and another 1.3 billion people who live downstream depend on rivers fed in part by glaciers and mountain snowpacks.
Climate change is having a severe impact on the amount of snow and ice precipitation in the Himalayas, which has serious implications for downstream water availability in both short and long term as up to 50% of the average annual flows in the rivers are contributed by snow and glacial melting. The melting glaciers would mean floods and fast run-offs in the rivers in the short term and droughts and water scarcity in the long term. Irregular availability of water is going to be the biggest hazard in future. This will alter the area’s erosion, river discharge and sediment patterns.