Pakistan is experiencing its worst flooding this century as rivers burst, flash floods and glacial lakes burst. At least one-third of the country is underwater. Several factors contributed to the extreme event, which displaced some 33 million people and killed more than 1,200, scientists said.
The disaster may have started with an alarming heatwave, researchers say. In April and May, the temperature in many places continued to exceed 40 ℃. On a muggy day in May, the temperature in Jakobabad reached 51°C. “These are not normal heatwaves – they are the worst in the world. We have the hottest place on earth in Pakistan,” said Malik Amin Aslam, the country’s former climate change minister and based in Islamabad.
Warm air can hold more moisture. That’s why meteorologists warned earlier this year that extreme temperatures could lead to “higher-than-normal” rainfall during the country’s July-September monsoon season, said Zia Hashmi, a water engineer at the Center for Global Change Impact Research in Islamabad. , speak in a personal capacity.
The heat also melted glaciers in the northern mountains, increasing the flow of water into tributaries that eventually flow into the Indus, said Athar Hussain, a climate scientist at COMSATS University in Islamabad. The Indus River, Pakistan’s largest river, runs through the country from north to south, providing water to towns and swathes of farmland along the way. It’s unclear how much excess glacier melt has flowed into the river this year, but Hashmi visited some high-altitude glacier areas in July and noticed high flow and muddy water in the Hunza River, which flows into the Indus. The mud indicates rapid thawing, he said, because the fast water picks up the sediment as it moves downstream. Several glacial lakes have breached the ice dams that normally confine them, releasing dangerous currents.
The heatwave also coincided with another extraordinary event – a depression or strong low pressure system in the Arabian Sea that brought heavy rains to Pakistan’s coastal provinces as early as June. “We rarely have large-scale depression systems get there,” Hussain said.
These unusual features were exacerbated by the early arrival of the June 30 monsoon, which “was generally wetter over a larger area for a long time,” said Andrew King, a climate scientist at the University of Melbourne in Australia.
As a result, Pakistan has so far received almost three times the average annual rainfall during the monsoon. The southern provinces of Sindh and Balochistan earn more than five times the average. “The flood is over,” Hashmi said.
Once on land, most of the water has nowhere to go. More than 1.2 million houses, 5,000 kilometers of roads and 240 bridges were destroyed. In Sindh, a slender lake tens of kilometers long has formed, and more water will flow into it, Aslam said. “The worst is not over yet.”
Some weather agencies are also predicting that the ongoing La Niña climate event — a phenomenon often associated with stronger monsoon conditions in India and Pakistan — will continue through the end of the year, King said. “It’s not a super strong link, but it may have played a role in enhancing rainfall.”
Human-caused global warming could also exacerbate downpours. Hussein said climate models suggest a warmer world would lead to more intense rainfall. Temperatures in Pakistan increased by 0.3 °C per decade between 1986 and 2015, above the global average.
The researchers and government officials also said other factors may have exacerbated the damage, including ineffective flood warning systems, poor disaster management, political instability and unregulated urban development. Lack of drainage and storage infrastructure, as well as large numbers of people living in flood zones, are also affected. “These are governance issues, but they’re trivial compared to the level of tragedy we’ve seen,” Aslam said.
This article is reproduced with permission, first published September 2, 2022.