Brown Clouds over South Asia causing high warming - studies
Jaipur, Nov 4 (UNI) Atmospheric Brown Clouds(ABC) above Indian Ocean and South Asia are causing higher atmospheric warming in southern flank of Hindu-Kush Himalaya and tipped as the probable cause for accelerated recession in Himalayan glaciers, studies have pointed out.
''The studies found that Atmospheric Brown Clouds in the above region is contributing as much as recent increase by humans and their green house gases,'' said noted environmentalist Syed Iqbal Husnain of Centre for Policy Research, New Delhi, quoting the recent studies by Ramanathan et al(2007).
Mr Husnain was presenting a paper on Impact of Climatic Change on Himalayan Glaciers and Glacier Lakes at the 12th World Lake Conference which concluded here on November 2.
''The total warming on the south flank of Hindu-Kush Himalaya is already around 1.2 degree Celsius which perhaps is the main cause of accelerated recession in Himalayan glaciers,'' Mr Hasnain added.
Elaborating at length the impact of ABC on glaciers, he said snow cover dynamics varied from Western to Eastern Himalaya and did determine the hydrological regimes of rivers.
In Western Himalaya, the monsoon component of rainfall was less as compared to the snow melt component. Therefore, deglaciation had profound impact on water resources of Western Himalayan rivers.
However, in Central and Eastern Himalayas, the seasoned snow melt peaked by last week of June, where monsoon rains between July and mid-September did sustain the flow of rivers.
''The direct implication of green house gas emissions and resulted global warming on the glacier environment is melting.
Moreover, deglaciation has far reaching implications on both biological and ecological systems,'' he said.
There were different reasons for ice melting. Thus, repercussions were also different depending up on regional and climatic variables, the paper stated.
Flood, sea level rise, fresh water scarcity threat to fauna and flora were major security implications of deglaciation, he pointed out.
The Himalayan glaciers did feed seven of the great rivers of Asia -- Ganga, Indus, Brahmputra, Salween, Mekong, Yangtze, Huang Hu -- and did ensure a year-round water supply to one billion people.
''In today's time, rivers had showed 3-4 per cent surplus water due to ten per cent rise in melting of glaciers of Western Himalaya and the 30 per cent increase in the Eastern Himalayan glaciers.
Mr Husnain further pointed out one more threat which did arise from creation of glacier lake -- Moraines at the terminus of glaciers.
Since Moraines were remarkably unstable, they could easily be destroyed by some disturbance and might lead to glacier lake outburst floods in down steam regions, warned Mr Husnain.