With rivers bursting, flash floods and glacial lakes bursting, Pakistan is experiencing its worst floods this century. At least one third of the earth is under water. Scientists say several factors contributed to the extreme event, which displaced about 33 million people and killed more than 1,200. Scientists say the disaster probably started with phenomenal heat waves. In April and May, temperatures in many places reached above 40 °C for a long time. On a steamy day in May, the city of Jacobabad reached 51°C. “These were not normal heat waves – they were the worst in the world. We had the hottest place on Earth in Pakistan,” says Malik Amin Aslam, the country’s former climate change minister, who is based in Islamabad.
Warmer air holds more moisture. So meteorologists warned earlier this year that extreme temperatures were likely to lead to “above normal” levels of rainfall during the country’s monsoon season, from July to September, says Zia Hashmi, a water resources engineer at the Global Change Impact Studies Center in Islamabad. , speaking for himself.
Melting glaciers
The intense heat also melted glaciers in the northern highlands, increasing the amount of water flowing into tributaries that eventually reached the Indus River, says Athar Hussain, a climate scientist at COMSATS University Islamabad. The Indus is Pakistan’s largest river and flows across the country from north to south, supplying cities, towns and large tracts of farmland along the way. It’s not clear exactly how much excess glacier melt has flowed into rivers this year, but Hashmi visited some high-altitude glaciated areas in July and noted high flows and muddy water in the Hunza River, which flows into the Indus. He says the silt indicates there was a rapid meltdown because fast water picks up sediment as it moves downstream. Several glacial lakes have broken through the dams of ice that normally hold them back, releasing a dangerous rush of water.
The heat waves also coincided with another extraordinary event – a depression, or system of intense low pressure, in the Arabian Sea, which already brought heavy rains to Pakistan’s coastal provinces in June. “Rarely do large-scale depression systems reach us,” says Hussain. These unusual features were then amplified by the early arrival of the monsoon on June 30, which “was generally wetter over a larger area for a very long time,” says Andrew King, a climate scientist at the University of Melbourne in Australia.
As a result, Pakistan has so far received almost three times its annual average monsoon rainfall. The southern provinces of Sindh and Balochistan received more than five times the average. “Floods are over,” says Hashmi. Once water is on land, it has nowhere to go. More than 1.2 million houses, 5,000 kilometers of roads and 240 bridges were destroyed. An elongated lake tens of kilometers wide has formed in Sindh and more water will continue to pour into it, Aslam says. “The worst is yet to come.
Other factors
•Some weather agencies have also predicted that the ongoing La Niña climate event a phenomenon typically associated with stronger monsoon conditions in India and Pakistan will continue through the end of the year, King says. “It’s not a super strong link, but it probably plays a role in increasing the rainfall.”
•Human-caused global warming could also be intensifying downpours. Climate models suggest that a warmer world will contribute to more intense rainfall, Hussain says. Between 1986 and 2015, temperatures in Pakistan rose by 0.3°C per decade, more than the global average.
•Researchers and public officials also say other factors likely added to the devastation, including an ineffective flood early warning system, poor disaster management, political instability and unregulated urban development. This is also related to the lack of sewage and storage infrastructure, as well as the large number of people living in floodplains. “These are governance issues, but they are minor in relation to the level of tragedy we are experiencing,” Aslam says.
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