Glacial lakes spell disaster

Glacier melting over a 47-year period has led to formation of seven new glacial lakes in Chandra-Bagha Basin of western Himalayas. According to Farjana Sikandar Birajdar, lead author of the study by IIT Mumbai, the melting of glaciers would reduce the ice mass balance even as it resulted in formation of new lakes with loose moraine. This in turn could lead to a sudden breach of the unstable moraine dams and the phenomenon of glacial lake outburst floods (GLOF), posing a serious hazard to settlements downstream.

Many previous studies in the Himayalan region revealed that the rate of melting was increasing, according to a news report in The Hindu. If the same trend continued, glaciers would vanish in the long-term, adversely impacting the storage of freshwater resources as also hydro-power generation.

Preliminary findings of an ongoing study by researchers from IIT, Bombay, showed that glacier lakes underwent continuous changes between 1963 and 2010. Geographical Information System tools and high resolution remote sensing technology were used to delineate glacier lakes situated in inaccessible Himalayan terrain. In all, 15 large glacier lakes situated at an elevation between 4069 meters to 5252 meters were chosen for monitoring the changes that occurred.

Continuous ice-melting due to glacier recession (loss of ice due to excess melting) caused the formation of seven new lakes near the mouth of the glaciers. These were formed as moraine-dammed lakes and the glacier-lake area was estimated to have increased approximately by 2591 sq.meters during the 47-year period. Moraine is a depositional feature of glacier. As the glacier starts moving, it accumulates small rocks, debris, ice fragments and soil.

Foundations of such moraine-dammed lakes should be strengthened. Besides by studying the rate of glacier melting, it could be predicted when a lake would burst and the people living downstream could be forewarned, the researchers said.

Of things to come...

Some glaciers of the Himalayas will continue shrinking for many years to come, despite anything! This forecast by Brigham Young University geology professor Summer Rupper comes after her research on Bhutan.

Published in Geophysical Research Letters, Rupper's most conservative findings indicate that even if climate remained steady, almost 10 percent of Bhutan's glaciers would vanish within the next few decades. What's more, the amount of melt water coming off these glaciers could drop by 30 percent.

Rupper says increasing temperatures are just one culprit behind glacier retreat. A number of climate factors such as wind, humidity, precipitation and evaporation can affect how glaciers behave. With some Bhutanese glaciers as long as 13 miles, an imbalance in any of these areas can take them decades to completely respond.

Snowfall rates in Bhutan would need to almost double to avoid glacier retreat, but it's not a likely scenario because warmer temperatures lead to rainfall instead of snow. If glaciers continue to lose more water than they gain, the combination of more rain and more glacial melt will increase the probability of flooding -- which can be devastating to neighboring villages.

"Much of the world's population is just downstream of the Himalayas," Rupper points out. "A lot of culture and history could be lost, not just for Bhutan but for neighboring nations facing the same risks." To illustrate the likelihood of such an outcome, Rupper took her research one moderate step further. Her results show if temperatures were to rise just 1 degree Celsius, the Bhutanese glaciers would shrink by 25 percent and the annual melt water would drop by as much as 65 percent

They are melting fast

After all the noise about the IPCC mis-quote, it still turns out glacier melting could pose a big danger to the Indian sub-continent.

Melting glaciers in the Himalayas and the Tibetan Plateau will decrease river flows and possibly cause food shortages in some regions of South Asia, but will not severely impact other river basins farther east, according to a study by Dutch scientists. Using satellite observations of glacial retreat, data on river flows, and computer modeling, the researchers from Utrecht University projected that rivers whose flow depends heavily on melting glaciers — including the Ganges, Brahmaputra, and, to a lesser extent, the Indus — could see water supplies decline by 20 percent by 2050.

That could threaten the food security of an estimated 60 million people in Pakistan and India, according to the study, published in the journal Science.

But rivers whose flows are more dependent on monsoon rains than glacial melt, such as China’s Yangtze and Yellow rivers, could actually see an increase in water supplies as monsoon patterns change this century due to rising temperatures. The study projected that the Yellow River basin could see a 9.5 percent increase in precipitation.

High time we started to manage water more effectively.