Melting of Major Glaciers in Himalayas: Role of Desert Dust and Anthropogenic Aerosols

Abstract

The Himalayan and Tibet Glaciers, that are among the largest bodies of ice and fresh water resource outside of the polar ice caps, face a significant threat of accelerated meltdown in coming decades due to climate variability and change (Hasnain et al., 2002; Lau et al., 2010; Shrestha et al., 2011; Scherler et al., 2011). The rate of retreat of these glaciers and changes in their terminus (frontal dynamics) is highly variable across the Himalayan range (Raina, 2010; Scherler et al., 2011). These large freshwater sources are critical to human activities for food production, human consumption and a whole host of other applications, especially over the Indo-Gangetic (IG) plains. They are also situated in a geo-politically sensitive area surrounded by China, India, Pakistan, Nepal and Bhutan where more than a billion people depend on them. The major rivers of the Asian continent such as the Ganga (also known as Ganges), Brahmaputra, Indus, Yamuna, Sutluj etc., originate and pass through these regions (Kulkarni et al., 2010; Kehrwald et al., 2008; Bookhagen & Burbank, 2010; Immerzeel et al., 2009, 2010) and they have greater importance due to their multi-use downstream: hydro power, agriculture, aquaculture, flood control, and as a freshwater resource. Recent studies over the Himalayan Glaciers using ground-based and space-based observations, and computer models indicate a long-term trend of climate variability and change that may accelerate melting of the Himalayan Glaciers (Lau et al., 2010; Prasad et al., 2009). Other studies also suggest a decreasing trend in snowfall, which has historically served as a main source of precipitation for maintaining the glaciers and fresh water resources in this region. Short-term studies of terminus and mass balance of the Himalayan Glaciers, based on in situ observations, show an accelerated rate of melting (Berthier et al., 2007; Das et al, 2010; Raina, 2010). However, several studies report the rate of melting and the corresponding change in temperature is found to vary across the entire Himalayan range (Naz et al., 2011a; Raina, 2010; UNEP, 2008). Observations from space-based lasers altimeters (such as GLASS/ICESat), show glacial thickening in certain areas such as the Karakoram (Naz et al., 2011b, personal communication) but increased melting in its surrounding regions. The