As record-setting heat blasts Pakistan, a glacial lake floods village

Record-high April temperatures over Pakistan melted glaciers faster than normal, triggering a flash flood Saturday in a village in the northern region of the country that wiped out part of a key bridge and damaged homes and buildings.

The event, known as a glacial lake outburst flood, occurs when water is suddenly released from a glacial lake because of a dam failure or breach. Warm temperatures over the past month accelerated snow and ice melt near an ice-dammed lake by Shishpar glacier, near Mount Shishpar, increasing the lake’s volume and likely causing the breach and water to overflow across the top.

Authorities are providing food, winterized tents and other necessities to affected families in Pakistan’s Hunza District.

The flooding that damaged the Karakoram Highway followed Pakistan’s hottest April on record since 1961, intensified by human-caused climate change. Over the past month, heat waves have baked the Indian subcontinent.

Several weather stations set record highs for April: Jacobabad hit its warmest daytime temperature at 120 degrees Fahrenheit (49 Celsius) on April 30; the Karachi airport reached its warmest nighttime temperature at 84.9 degrees Fahrenheit (29.4 Celsius), also on April 30.

While most glacial lakes typically form in May, rapid snowmelt caused the lake near Shishpar to form a month earlier in April. Over the past 20 days, the lake expanded by 40 percent. Pakistan’s climate change minister warned that the country’s vulnerability to flooding is high because of the heat wave hitting the region.

“The surprising element was the timing. It’s too early in the spring,” said Umesh Haritashya, a glaciologist at the University of Dayton. But he said the higher temperatures and rapid snowmelt likely contributed “towards the filling of the lake and that may have caused melting a lot earlier

Two power plants in Hassanabad were also reportedly swept away by the flood.

“The entire lake has drained out. This generally doesn’t happen,” Haritashya said. “Basically all the water that was there in the lake is now drained out. And that’s probably why it caused the devastation downstream.”

Glacial floods pose an increasing hazard in Pakistan’s northern mountainous regions as global temperatures rise. As mountain glaciers rapidly melt, more than 3,000 glacial lakes have developed in the highly glaciated northern areas of Gilgit-Baltistan and Khyber Pakhtunkhwa. According to the United Nations, 33 of those lakes are prone to hazardous flooding.

Researchers have studied the Shishpar lake because of its potential flooding risk. In 2017, the Shishpar glacier began surging, or rapidly moving forward. As it advanced, it blocked a river by the nearby Muchuhar glacier. The meltwater from the Muchuhar glacier began collecting in a pool until water levels rose to form an ice-dammed lake. The lake near Shishpar glacier appeared around November 2018.