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.”
The Gilgit-Baltistan Disaster Management said Authority the lake discharged around 10,000 cubic feet per second, enough to sweep away scaffolding on a portion of the Hassanabad bridge. Authorities created an alternate route around the region. The National Highway Authority announced it will install a temporary bridge within a month, while construction of a new bridge will be completed in six to eight months.
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.”
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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 Nations33 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.
Ice-dammed lakes are typically unstable, but most slowly drain over the course of a season without creating major problems. However, sometimes ice dams can suddenly collapse, or lake water spills over the dam, causing floods. In 2019, the lake reached its maximum area and breached the dam, damaging part of the Karakoram Highway.
Hunza Deputy Commissioner Muhammad Usman Ali said his region has routinely been hit by floods caused by glacial melt since 2018.
“Luckily we don’t have that many residents in the areas surrounding the glacial lake,” and they had time to move to avoid the most recent flooding and avoid any loss of life, he said. However, he added the waters destroyed agricultural land, power projects and some houses.
“This glacier melting is worrisome because it’s now happening on an almost annual basis,” he said, noting that many regions of the country are affected. “All of this is related to climate change.”
More flooding is feared when temperatures are expected to spike again later this week. Extremely hot weather is predicted for Pakistan this week, with maximum temperatures as high as 122 degrees Fahrenheit (50 Celsius). The highest temperatures are anticipated Wednesday and Thursday.
Irfan Rashid, a professor at the University of Kashmir, said glaciologists cannot draw a direct link between global warming and the surging of an individual glacier, like Shishpar. However, the warm temperatures that led to rapid snowmelt are exacerbated by climate change.
As greenhouse gas emissions from fossil fuel burning increase global temperatures, Pakistan has warmed around 2.1 degrees Fahrenheit (1.2 Celsius) since the preindustrial era. Projections from Berkeley Earth show the country could warm 6.3 degrees Fahrenheit (3.5 Celsius of warming) by 2100, assuming carbon emissions are stabilized in the near future and then slowly decline.
“Pakistan has the highest number of glaciers outside the polar region and many are losing mass due to high global temperatures,” tweeted Sherry Rehman, Pakistan’s climate change minister. “We need global leaders to reduce emissions.”
Shaiq Hussain in Islamabad, Pakistan, contributed to this report.