Mountains, which are symbolized as water towers of the world and hotspots for biological diversity, cover about 25% of the earth’s surface. Mountains provide direct life support to one tenth of world population’s and support the habitats downstream through the ecosystem services. Mountains are one of the sensitive ecosystems, which will and is greatly being impacted by the ongoing phenomenon of climate change.
Mountains supply fresh water to half of the world’s population. Mountain water is crucial for livelihood sustenance, hydropower production and environmental services on earth. But, the change in precipitation and temperature pattern is showing the impact on the hydrological pattern of the mountains. According to Solomon et al. 2007, Intergovernmental Panel on Climate Change Fourth Assessment Report (IPCC AR4) projections suggest that there is an increase in global average precipitation, but a decrease in precipitation. In such situation, the subtropical zone which relies on mountain for water will be impacted with short of water. Also, the IPCC Technical Paper on Climate Change and Water, 2008, outlines with high confidence that global warming will cause changes in the seasonality of river flows where much precipitation currently fall as snow in winter. Various scientists have stated ongoing impact of climate change on the mountain has been increased runoff from rapid ice melt in the basin at high elevation but over the next few decades decrease in water yield is to be expected due to global warming. So, it is the time we have to hold a question, of future availability of water from the mountains.
Glaciers, which are the huge mass of water stored as ice in the mountains and studies have shown that the impact of warming on glaciers vary according to altitude. Glaciers at the high and mid- altitude are impacted by climate change in the form ice warming only. Whereas those located at lower altitude, are directly impacted by mass loss and a change in geometry. There are many studies being done on glacier melting and shrinking around the mountain ranges of the globe. Glacier inventory using the satellite imagery has shown that even if the global warming be limited to 2°C, it will put many small to medium size glaciers on the verge of disappearance in within decades. Scientists have been assessing the loss of thickness of glaciers around the world and their studies indicate that there is peak loss in thickness of glacier over the period of 1980 to 2006.Such melting down of glaciers will result in the release of loose rocks and soil and can cause rockfall, debris flow, and mud flow. It does bring the risk of formation of glacier lake and along comes the threat of lake outburst which can cause casualties in the downstream community.
A study in the Venezeulan Andes by Schubert in 1992, using photographs from 1885 till his study year showed that the snowline has risen from 4100 meters to 4700 meters. Numerous study on past trend analysis on mountain runoff using series of data of Western United States has shown that precipitation is falling as rain instead of snow in winter and snowmelt occurs earlier resulting in changed in the timing of runoff. Such a reduction of snow cover will have series of implications; such as an increase in early seasonal runoff, leading to drier soil and vegetation, shift of vegetation belt, and greater risk of the hazard of fire and landslide.
Those are the implications on mountain water resources by our human activities. In gist, water availability from mountain in future will decline, with increasing threats of glacier lake burst and melting down of snow.
A thought came to my mind that, how would our earth be like if all the snow up in the mountains melt and the mountains go bare and dry. To me, that would be the end of the life on earth. But then, the only difference to my thought from reality is time. Such a nightmare might be at our door tomorrow if we don’t act now to preserve our mountains and mitigate climate change