Understanding Glacial Retreat in the Indian Himalaya: Historical Trends and Field Studies from a Large Glacier

Introduction

The Cryosphere plays a major role in the Earth’s climate system by impacting on the surface energy budget, the water cycle, sea level etc. and has control on the physical, biological and social environment over a major portion on the Earth. The cryosphere is most sensitive to temperature change hence capable of providing the most visible signatures of climate change. There are many indicators of climate change like changes in surface temperature, precipitation, extreme weather events, glaciers, ocean and land ice and sea level. Icesheets and glaciers changes are closely related with the global sea level changes impacting the global ocean circulation and marine ecosystems. The warming trend has been reported in the vertical profiles of temperature measured through the entire thickness of mountain glaciers, or through ice sheets climate over recent decades (Lüthi and Funk, 2001; Hoelzle et al., 2011). The loss of glaciers and snow cover near populated areas have direct impacts on the livelihood of the local communities in terms of water resources for drinking, agriculture, hydropower etc.

Over the last few decades, changes in climate and local weather conditions have impacted the world’s glaciers both in terms of structure and characteristics, reflected in the form of advancement or retreat of glacial snouts (IPCC, 2007; UNEP, 2007). The changes in the length, width, area, volume and mass balance of the glaciers are among the most directly visible signals of global warming and these changes are the primary reasons why glacial observations have been used for climate system monitoring for many years (Haeberli, 1990; Wood, 1990), especially in areas where time series data on climate (mainly temperature and precipitation) is difficult to get and where climate change signals are not yet clear (Yadav et al., 2004; Roy and Balling, 2005). Thirty reference glaciers that have been studied in detail since 1975 show an average annual mass loss of 0.58 metres (m) water equivalent in the past decade, which is four times the rate for the period 1976-85 (UNEP, 2007).The IPCC, 2013 report (The physical science basis) clearly reflects the warming trend on the planet and state that “The last three decades has been successively warmer at the Earth’s surface than any preceding decade since 1850 while in the Northern Hemisphere, 1983–2012 was likely the warmest 30-year period of the last 1400 years (medium confidence)”. Unnatural rates of glacial melting, related to the changing climate, can have serious implications on the hydrology of the associated river systems and consequently on the livelihoods of millions of people who are dependent on these rivers and their ecosystems.(Stern,2007). Overexploitation of water resources and changes in hydrological cycle could be vital to future developmental strategies of the fertile belt of Northern India where agricultural productivity, irrigation etc.is to a large extent dependent on availability of freshwater resources (Mall et al, 2006).

The right approach, thus, in addressing these impacts is to have a better scientific understanding through long-term observations and analysis of the interactions of the different components of the mountain ecosystems with their climate. Then the lager data can be helpful in predicting the future scenarios and utilizing the information to formulate effective adaptation and management strategies. There is also a pressing need for disaster management and rehabilitation policies in areas affected by the glacial retreat, particularly focusing on agriculture, meadows and other livelihood support structures of the local people.