Melting of major Glaciers in the western Himalayas: evidence of climatic changes from long term MSU derived tropospheric temperature trend (1979–2008)

Abstract

Abstract. Global warming or the increase of the surface and atmospheric temperatures of the Earth, is increasingly discernible in the polar, sub-polar and major land glacial areas. The Himalayan and Tibetan Plateau Glaciers, which are the largest glaciers outside of the Polar Regions, are showing a large-scale decrease of snow cover and an extensive glacial retreat. These glaciers such as Siachen and Gangotri are a major water resource for Asia as they feed major rivers such as the Indus, Ganga and Brahmaputra. Due to scarcity of ground measuring stations, the long-term observations of atmospheric temperatures acquired from the Microwave Sounding Unit (MSU) since 1979-2008 is highly useful. The lower and middle tropospheric temperature trend based on 30 years of MSU data shows warming of the Northern Hemisphere's midlatitude regions. The mean month-to-month warming (up to 0.048±0.026 • K/year or 1.44 • K over 30 years) of the mid troposphere (near surface over the high altitude Himalayas and Tibetan Plateau) is prominent and statistically significant at a 95% confidence interval. Though the mean annual warming trend over the Himalayas (0.016±0.005 • K/year), and Tibetan Plateau (0.008±0.006 • K/year) is positive, the month to month warming trend is higher (by 2-3 times, positive and significant) only over a period of six months (December to May). The factors responsible for the reversal of this trend from June to November are discussed here. The inequality in the magnitude of the warming trends of the troposphere between the western and easternCorrespondence to: A. K. Prasad (aprasad@chapman.edu) Himalayas and the IG (Indo-Gangetic) plains is attributed to the differences in increased aerosol loading (due to dust storms) over these regions. The monthly mean lowertropospheric MSU-derived temperature trend over the IG plains (dust sink region; up to 0.032±0.027 • K/year) and dust source regions (Sahara desert, Middle East, Arabian region, Afghanistan-Iran-Pakistan and Thar Desert regions; up to 0.068±0.033 • K/year) also shows a similar pattern of month-to-month oscillation and six months of enhanced and a statistically significant warming trend. The enhanced warming trend during the winter and pre-monsoon months (December-May) may accelerate glacial melt. The unequal distribution of the warming trend over the year is discussed in this study and is partially attributed to a number of controlling factors such as sunlight duration, CO 2 trends over the region (2003)(2004)(2005)(2006)(2007)(2008), water vapor and aerosol distribution.

Spatio-temporal variability of dust aerosols over the Sistan region in Iran based on satellite observations

“…Rosenfeld et al, 2001;Gautam et al, 2009a;Prasad et al, 2009;Anton et al, 2011;Christopher et al, 2011;Valenzuela et al, 2012).…”

Influence of continental advection on aerosol characteristics over Bay of Bengal (BoB) in winter: results from W-ICARB cruise experiment

“…The ABC can be even 3-km thick and can be transported several kilometers downwind, affecting south India and the adjoining oceanic regions (Ramanathan et al, 2005). Furthermore, they absorb the solar radiation heating the atmosphere, thus causing a temperature anomaly over northern India (Gautam et al, 2010) able to cause the melting of the Himalayan glaciers (Prasad et al, 2009;Menon et al, 2010).…”

Change in snow cover area of Brahmaputra river basin and its sensitivity to temperature

“…Lal and Singh (2001) and Lal (2001) have reported that the average annual mean surface temperature over Indian sub-continent is likely to increase by about 2.7 and 3.8 °C during the decades of 2050 and 2080 s, respectively. Dyurgerov and Meier (2005) and Prasad et al (2009) mentioned that in recent years, the glaciers and snowfields of the Himalaya-KarakoramHindu Kush (HKH) mountain belts and Tibetan plateau are found to be amongst the fastest receding glacial and snow covers in the world. Again, Kulkarni et al (2007) and Raina (2009) said that the simultaneous fragmentation of the glaciers along with glacial retreats has also degraded the total areal coverage of perennial snow and ice in the HKH region.…”