"Himalaya has been warming at a rate much higher than the global average. The results of studies on the glaciers of three basins – Indus, Ganga and Brahmaputra conducted over three decades are discussed.
The 2400 km long actuate Himalaya-Hindu Kush mountain range supports largest accumulation of snow and ice following the Polar Regions of Arctic and Antarctic and Greenland. Apart from the several peaks that attain more than 8000 m heights above mean sea level, the Himalaya also brings to life many major rivers that support about1.3 billion people in one of the most densely populated regions of the world. Researchers have attempted to understand the feedback mechanism between climate forcing and glacier response by mapping of glacier characteristics such as their distribution pattern, changes in their length and thickness, mass-balance, basement topography etc. It has been established that adjoining glaciers can display dissimilar behaviour even in similar regional climatic settings due to varying geometry, bedrock topography or debris cover, thus necessitating their long term monitoring to arrive at a conclusion regarding their dynamics.
The data compiled by Bhutiyani (2013) shows that elevation-dependent warming (EDW) can accelerate the rate of change in mountain ecosystems, cryospheric systems, hydrological regimes and biodiversity. The Himalaya has a profound impact on regional climate and its cryosphere gets affected by changing climatic systems. The Himalaya is warming much faster than the rest of the globe. It affects wind circulation and storm tracks over large distances. The high altitude segments of Himalaya–the Siwaliks (>3000m), Pirpanjal (>5000m), Greater Himalayan Ranges (>6000 to 7000m), Zanskar Range (>7000m) exhibit warming trends while decreasing trends are noted only in the Karakroum range (>8000m). Due to its unique geographic, orographic position and high altitude, it faces rapid changes in the weather patterns and ecosystem.
The glaciers, snow-capped mountains, permafrost soils; cold deserts and wetlands hold large reserves of carbon. Climate change processes have caused changes in rainfall pattern, recession of glaciers, loss of snow cove, scarcity of water and forced changes in cultivation patterns, bringing the Himalayan earth system to a critical stage that necessitates intervention for its protection and preservation.
Monitoring, studying and understanding various scientific and related social aspects of the Himalaya pertaining to meteorological parameters, hydrological cycle and glaciers are of vital importance for managing river flows, irrigation, power generation, conserving the biodiversity and sustaining the life systems of the Himalayan terrain, the people and the plains below. Glacier melt water discharge measurement by the Geological Survey of India (Shukla, 2017) in Hamtah glacier shows strong positive and significant correlation with temperature as well as ablation and relatively weak correlation with precipitation. The glacier also does not show any appreciable lag between ice melt generation and its release and thereby indicates that there is no storage of glacier melt within the glacier.
The glacier inventory of the Himalaya prepared by Space Applications Centre (SAC) identifies a total of 34919 glaciers that occupy an area of around 75,779 sq km. The distribution of these glaciers in three main basins–the Indus, the Ganga and the Brahmaputra are 1. INDUS basin-18576 glaciers, area-36843sq km. 2.GANGA basin-6237 glaciers, area-18393sq km. 3.BRAHMAPUTRA basin-10106 glaciers, area-20543sq km.
SAC is also undertaking snow cover mapping as also mapping and monitoring of glacial and peri-glacial lakes in the Indian Himalaya region to develop a model for glacial lake outbursts (GLOF) harzard based on vulnerability Index (Bahuguna, 2017). The results of studies published by SAC on the long term monitoring of snout of glaciers in three main basins-Ganga, Indus and Brahmaputra in the two periods of 1989-90 to 2001-04 and 2001-02 to 2010-11 have presented a contrasting picture. During the period of 1989-90 to 2001-2004, 76 per cent have retreat,7 percent have advanced and 17 per cent have shown no change. As compared to this, during the next decade i.e. 2001-02 to 2010-11, only 12.3 per cent glaciers have shown retreat, 86.6 per cent of glaciers have shown stable fronts and 0.9 per cent has shown advancement (Ajai, 2017).
Romshoo (2017) has pointed out that the Kashmir Himalayas have lost ~20 per cent of the glacial mass during last six decades. He has cautioned that shifting of hydrograph peaks, change in the precipitation and low availability of storage capacity of water in Kashmir should be a matter of grave concern for policy makers and that water issues, if, not understood in the right perspective have the potential to complicate south Asian security.
Apart from SAC the multiple agencies in India–several universities, Geological Survey of India, Wadia Institute of Himalayan Geology, the NationalCentre for Antarctica and Ocean Research etc., are monitoring various glaciers by field and remote sensing techniques showing a wide mismatch in the findings. This highlights the need for the standardization of tools and techniques and parameterization as also necessary for ground checks of the interpreted results from satellite data. Ravindra (2017) has highlighted a need for coordination among these institutions to ensure proper utilization of scarce manpower in the field of glaciology and also to cover more and more the spread of glaciers.
The Himalayan ecosystem is vital to the ecological security of the Indian landmass. It is highly vulnerable and susceptible to the impacts and consequences of excessive anthropogenic emissions and developmental paradigms of modern society. It needs to be protected to conserve its biodiversity for providing a rich base of high value agriculture, and the development of sustainable tourism. The issues pertaining to the preservation and protection of this fragile Himalayan ecosystem, understanding the coupling between this ecosystem and climate factors and providing inputs for Himalayan sustainable development come under the preview of the national Action Plan on Climate Change (NAPCC).
Lateral moraine:- Accumulation of heavy sediment load eroded from valley wall along the edge of the glacier where it is seen as a parallel ridge.
Snout:- It is the end of a glacier at any given time. It could be advancing or retreating.
Ablation area:- The total amount of ice that a glacier loses each year.
Snow line:- Irregular line located along the ground surface where accumulation of snowfall equals ablation.
Accumulation area:- Amount of snow added annually to a glacier.
Tributary glacier:- Merges into trunk glacier and contributes mass from its separate accumulation basin.