Abstracts of papers to be presented in session on Himalayan Glaciers
Glacier Recession vis-à-vis Weather Cycles and Human Activity
By: V.K. Raina
Glaciers in India are restricted to the Extra-Peninsular area i.e. the Himalayan mountain chain that extends over a linear stretch of almost 1,600km from North West to north east within the latitudes 270N to 360N and longitudes 72ºE to 96ºE. Estimated number of glaciers spread over the states of Jammu & Kashmir, Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh is around 9,575 with a glacier Ice cover-40,218sqkm- comprising glaciers that vary in length, on an average, from less than 1/2 km to 5km, along with some exceptionally large glaciers like 74km long Siachen glacier, the second largest glacier outside the Polar Regions.
Various theories have been put forward to explain the presence and preservation of glaciers in the Himalayas. One that is more appropriate is based on the presumption that the cold environment of the high altitude-a consequence of the uplifting of the Himalayas-is conducive and responsible for the development and preservation of the glaciers.
Glacier regimen studies carried out and in progress, in the Himalayas, have revealed that the annual precipitation- primarily precipitation in the form of snow in the winter has a definite and major role to play in the increase and or depletion of the mass of a glacier. Obviously the annual precipitation combined with the cold environment of the high altitude must have lead to the deposition of snow/ice, to begin with, followed by accumulation to the extant of the development of the glacier.
Uplift of the Himalayas began at the end of the Cretaceous Period around 67 million years ago and it is believed to have attained the present altitudes around mid-Miocene, 15 million years back. One would expect the cold climate, annual precipitation and environment conducive to the preservation of snow and ice to have come into existence much earlier than the Pleistocene Epoch of the Quaternary Period around 1.7 million years back. It is obvious that the cold environment, conducive to the deposition and preservation of the ice cover that would give rise to the glaciers needed some sort of climatic stimulus, better known today as the ‘Ice Age’. Latter was not a continuous phase. There were periods of cold climate-glacial-with accumulation and advance of ice cover alternating with periods of warm climate-inter glacial-and ice degeneration. Within the period of cold climate there were periods of more cold-Stadial- and relatively less cold periods-inter-Stadial.
Glacier ice cover of the Himalayas is the consequence of the Ice Age. Evidence-exposure dates- have recently come forth to indicate the existence of glaciers around the Gunz glacial stage of the Quaternary Ice Age, i.e. around 330,000-470,000 years from present. There is a distinct possibility that there was or may have been ice cover in the upper reaches of the Himalayas well before the glaciers made their appearance. In the Central Himalayas, again based on very limited dating data, existing glacier ice cover is the consequence of the last Glacial-Wurm-period 50k BP that ended around 15-12k BP and the extension of most of the glaciers, in the Himalayas, at that stage, was any where between 2-10km from the current snout position.
Glaciers in the Himalayas have recorded considerable shrinkage in mass and volume since and have vacated substantial area from under the glacier cover in response to what appears to be the climatic change that began with the end of the Last Glacier Maximum. This recession/vacation of the area along the glacier front, barring one odd glacier, here and there, has been continuous during the recent historical period, i.e. since the observation of glaciers in the Himalayas began. Ecological changes that must have followed gave rise to an environment that is unique to the Himalayan mountain chain.
Shrinkage and the glacier retreat have been episodic with periods when it enhanced to considerable levels.
No advance of any major nature was recorded by glaciers, in general, during the last one and a half century except by the Surging Kumdan glaciers- a separate entity.
All the activities related to glaciers -mainly recession-are in response to climatic changes and the human activity per se has had no role to play. In recent years, having become conscious of the environmental changes likely to take place under the impact of global warming, resultant impact has been taken to what can be called absurd levels. Human activity like increasing number of pilgrims and vehicular traffic is being suggested as the reason for rapid glacier degeneration in the Himalayas, which in due course will lead to major ecological changes.
An attempt has been made through detailed and systematic presentation-by sitting the example of three glaciers namely: Gangotri glacier in Uttarakhand, Sonapani glacier in Himachal Pradesh and Kolahoi glacier in Jammu & Kashmir- from relatively different climatic zones, to the fact that the recession exhibited by the glaciers, in the Himalayas, during the last century or two, is a natural phenomenon in response to:
• Secular change- fluctuations over long periods of time, due to what can be identified as “world causes” that overrule local factors of climate, weather, and topography.
• Periodic change- fluctuations that are believed by some to be due to climatic or weather cycles of comparatively short duration.
• And neither is influenced by the human activities in the neighbourhood of the glacier.
Impact of climate change on the glacier resources of Jammu and Kashmir State, India
Physiographically, J&K State has wide altitude variations due to Trans-Himalayan, Greater Himalayan, Ladakh, Zanskar and Pir Panjal ranges. The major drainages in the area are Indus,Shyok,Kishanganga,Jhelum and partially drains by Chenab and Satluj. The sustenance of the glaciers is mainly dependent on the aspect, altitude and nourishment in form of snow which is due to moisture laden “Western Disturbance Convection”(WDC).
Detailed glacier inventory of the major drainages in J&K State has been computed as per the guidelines of Temporary Techniical Secretariat(TTS) for World Glacier Inventory(WGI) (Sangewar & Shukla,2009). There are 5362 glaciers in addition 535 glaciers in Gilgit area were computed as prelimnary glacier inventory (Raina,1988). Thematic compilation based on the distributions of glaciers within the districts of J&K State had been also computed (Sangewar & Siddiqui,2010).Of the fourteen districts excluding the Pak Occupied Kashmir(POK), seven districts are glacierised.
Orientation-wise, N - oriented glaciers constitute 28.05%, NW oriented glaciers 15.33% and NE oriented glaciers are 19.92%.
Impact of climate change
Glaciology Division, Geological Survey of India has undertaken glaciers studies and related studies during the eighties and nineties of Twentieth century. The studies included mass balance of glaciers viz, Neh-Nar, Rulung(Deepak et al,2001),monitoring of glaciers viz. Harmukh, Machoi, Khardung,Siachin(Raina & Sangewar,2007),detailed glacier inventory and other related studies viz, avalanche studies(Raina et al,1985,Kaul M.K,1988),safety of engineering structures etc.
Synthesis of the data on monitoring of the glaciers based on field studies and remote sensed data it was observed that the recessional pattern of the glaciers in J&K do not show any remarkable shift in the present time as recorded even for smaller glaciers viz.,Rulung or Khardung and similarly the pattern of mass balance as observed during eighties and of the present day mass balance studies.
Understanding the impact of climate change is elusive in the context of sporadic data available presently. Therefore, it is suggested to undertake a multi-disciplinary programmes with goals to generate long term data in the different climatic zones for better understanding the various geomorphic process and changes brought due to variations in climate.