Warmer air is thinning most of the vast mountain range’s glaciers, known as the Third Pole because they contain so much ice. The melting could have far-reaching consequences for flood risk and for water security for a billion people who rely on meltwater for their survival.
Vaishnavi Chandrashekhar at the Yale Environment360: Spring came early this year in the high mountains of Gilgit-Baltistan, a remote border region of Pakistan. Record temperatures in March and April hastened melting of the Shisper Glacier, creating a lake that swelled and, on May 7, burst through an ice dam. A torrent of water and debris flooded the valley below, damaging fields and houses, wrecking two power plants, and washing away parts of the main highway and a bridge connecting Pakistan and China.
Pakistan’s climate change minister, Sherry Rehman, tweeted videos of the destruction and highlighted the vulnerability of a region with the largest number of glaciers outside the Earth’s poles. Why were these glaciers losing mass so quickly? Rehman put it succinctly. “High global temperatures,” she said.
Just over a decade ago, relatively little was known about glaciers in the Hindu Kush Himalayas, the vast ice mountains that run across Central and South Asia, from Afghanistan in the west to Myanmar in the east. But a step-up in research in the past 10 years — spurred in part by an embarrassing error in the Intergovernmental Panel on Climate Change’s 2007 Fourth Assessment Report, which predicted that Himalayan glaciers could melt away by 2035 — has led to enormous strides in understanding.
Scientists now have data on almost every glacier in high mountain Asia. They know “how these glaciers have changed not only in area but in mass during the last 20 years,” says Tobias Bolch, a glaciologist with the University of St Andrews in Scotland. He adds, “We also know much more about the processes which govern glacial melt. This information will give policymakers some instruments to really plan for the future.”
That future is daunting. New research suggests that the area of Himalayan glaciers has shrunk by 40 percent since the Little Ice Age maximum between 400-700 years ago, and that in the past few decades ice melt has accelerated faster than in other mountainous parts of the world. Retreat seems to have also recently initiated in Pakistan’s Karakoram range, one of the few areas where glaciers had been stable. Depending on the level of global warming, studies project that at least another third, and as much as two-thirds, of the region’s glaciers could vanish by the end of the century. Correspondingly, meltwater is expected to increase until around the 2050s and then begin to decline.
These changes could have far-reaching consequences for hazard risk and food and water security in a heavily populated region. More than a billion people depend on the Indus, Ganges, and Brahmaputra river systems, which are fed by snow and glacial melt from the Hindu Kush Himalaya region, known as the world’s “Third Pole” because it contains so much ice. Peaking in summer, meltwater can be a lifesaver at a time when other water sources are much diminished.
But increased melt may also trigger landslides or glacial lake outburst floods, known as GLOFs, scientists warn. Or it could aggravate the impact of extreme rainfall, like the deluge that caused recent massive flooding in Pakistan. Changes in melt could also affect the safety and productivity of the region’s expanding hydropower industry. Countries like Nepal already get most of their electricity from hydropower; others, like India, are planning to increase capacity of this low-carbon energy source. Around 650 hydro projects are planned or underway in high-altitude locations across the region, many of them close to glaciers or glacial lakes.
The Indus basin, which largely falls in Pakistan and northwest India, is particularly vulnerable to long-term changes in runoff, scientists say. That’s because snow and ice melt comprise as much as 72 percent of river runoff in the upper Indus, compared with between 20 and 25 percent in the Ganges and Brahmaputra rivers (the latter two depend on monsoon rain).
Farmers in Gilgit-Baltistan are already affected, according to Aisha Khan, CEO of the Mountain and Glacier Protection Organization in Islamabad, who has been visiting the region regularly for two decades. In one village, Khan says, unpredictable changes in the timing of snowmelt, which supplies water for irrigation, have led local men to abandon their fields and migrate to cities. In another settlement, increased velocity and volume of river flow have eroded banks and swept away land. “These communities can’t afford to invest in flood and erosion protections,” she says. More here.
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Honorary contributors to DesPardes: Adil Khan, Ajaz Ahmed, Anwar Abbas, Arif Mirza, Aziz Ahmed, Bawar Tawfik, Dr. Razzak Ladha, Dr. Syed M. Ali, G. R. Baloch, Haseeb Warsi, Hasham Saddique, Jamil Usman, Jawed Ahmed, Ishaq Saqi, Khalid Sharif, Majid Ahmed, Masroor Ali, Md. Ahmed, Md. Najibullah, Mushtaq Siddiqui,, Mustafa Jivanjee, Nusrat Jamshed, Shahbaz Ali, Shahid Hamza, Shahid Nayeem, Shareer Alam, Syed Ali Ammaar Jafrey, Syed Hamza Gilani, Shaheer Alam, Syed Hasan Javed, Syed M. Ali, Tahir Sohail, Tariq Chaudhry, Usman Nazir