A third of the country is under water due to a severe heat wave and prolonged monsoon that has wasted record amounts of rain.


With rivers breaking their banks, flash floods and glacial lakes bursting, Pakistan is facing its worst floods of the century. At least one-third of the country is under water. Scientists say many factors contributed to the extreme event, which displaced nearly 33 million people and killed more than 1,200.

Researchers say the catastrophe was probably triggered by unusual heat waves. In April and May, temperatures reached above 40 °C for extended periods at many places. On a hot day in May, the temperature in Jacobabad city reached 51 degrees Celsius. "These were no ordinary heat waves - these were the world's worst.  Pakistan was the hottest place we had on Earth," says Malik Amin Aslam, the country's former climate change minister based in Islamabad.

Warm air can hold more moisture. Zia Hashmi, a water resources engineer at the Global Change Impact Studies Center in Islamabad, says that earlier this year, meteorologists warned that extreme temperatures could result in the country's monsoon season, starting in July. There could be "above normal" levels of rainfall by September. , speaking in his personal capacity.

Snow melting

Athar Hussain, a climate scientist at COMSATS University Islamabad, says the intense heat also melted glaciers in the northern highlands, increasing the amount of water flowing into tributaries that eventually flow into the Indus River. The Indus River is Pakistan's largest river, and runs the length of the country from north to south, consuming large swaths of cities, towns and agricultural land along the way. It's not clear exactly how much snowmelt has flowed into the rivers this year, but Hashmi visited some high-altitude snowfields in July and noticed high flows and muddy water in the Hunza River, which flows into Sindh. Bridges. They say the mud indicates rapid melting, as fast water picks up sediment as it moves downstream.


The heat waves also coincided with another unusual event - a depression, or a system of severe low pressure in the Arabian Sea, that brought heavy rains to Pakistan's coastal provinces in early June. "We rarely have large-scale depression systems," Hussain says.

The unusual features were then compounded by the early arrival of the monsoon on June 30, which was "generally wet over a large area for a very long period," says Andrew King, a climate scientist at the University of Melbourne in Australia.

The effect is that Pakistan has so far received an average of three times the annual rainfall during the monsoon period. The southern provinces of Sindh and Balochistan have recovered five times more than the average. "The flood is over," says Hashmi.

Once on land, most of this water has nowhere to go. More than 12 lakh houses, 5 thousand km of roads and 240 bridges have been destroyed. Aslam says that in Sindh, a long lake has formed, tens of kilometers wide, and more water will continue to flow into it. "The worst is not over."

Other factors

King says some weather agencies also predict that the ongoing La Nina weather event — a phenomenon typically associated with strong monsoon conditions in India and Pakistan — will continue through the end of the year. . "It's not a very strong link, but it's probably contributing to increased precipitation."

Human-induced global warming can also intensify rainfall. Hussain says climate models suggest a warmer world will contribute to more intense rainfall. Between 1986 and 2015, temperatures in Pakistan increased by 0.3 °C per decade, which is higher than the global average.

Researchers and government officials also say other factors likely contributed to the disaster, including an ineffective early warning system for floods, poor disaster management, political instability and unplanned urban development. Lack of drainage and storage infrastructure, as well as the large number of people living in flood-prone areas, are also implicated. "These are governance issues, but they are very minor compared to the level of tragedy that we are seeing unfold," says Aslam.