Why are Pakistan’s floods so extreme this year?

 

If you do not make a continuing effort to reduce your use of energy and material (whose creating and transportation use energy), and/or you vote for politicians who are blocking action on dealing with climate disruption, you are helping to create horrible situations like this.

 

https://www.nature.com/articles/d41586-022-02813-6

 

 One-third of the country is under water, following an intense heatwave and a long monsoon that has dumped a record amount of rain.

Smriti Mallapaty

02 September 2022

 

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

Researchers say the catastrophe probably started with phenomenal heatwaves. In April and May, temperatures reached above 40 °C [104F] for prolonged periods in many places. On one sweltering day in May, the city of Jacobabad topped 51 °C [124F]. “These were not normal heatwaves — they were the worst in the world. We had the hottest place on Earth in Pakistan,” says Malik Amin Aslam, the country’s former minister for climate change, who is based in Islamabad.

Warmer air can hold more moisture. So meteorologists warned earlier this year that the extreme temperatures would probably result in “above normal” levels of rain during the country’s monsoon season, from July to September, says Zia Hashmi, a water-resources engineer at the Global Change Impact Studies Centre in Islamabad, speaking in his personal capacity.

Glacial melt

The intense heat also melted glaciers in the northern mountainous regions, increasing the amount of water flowing into tributaries that eventually make their way into the Indus river, says Athar Hussain, a climate scientist at COMSATS University Islamabad. The Indus is Pakistan’s largest river, and runs the length of the country from north to south, feeding towns, cities and large swathes of agricultural land along the way. It isn’t clear exactly how much excess glacial melt has flowed into rivers this year, but Hashmi visited some high-altitude glaciated regions in July and noticed high flows and muddy water in the Hunza River, which feeds into the Indus. He says the mud suggests that there has been rapid melting, because fast water picks up sediment as it moves downstream. Several glacial lakes have burst through the dams of ice that normally restrain them, releasing a dangerous rush of water.

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 Human-induced global warming could also be intensifying downpours. Climate models suggest that a warmer world will contribute to more frequent and more intense rainfall, says Hussain. Between 1952 and 2009, temperatures in Pakistan rose by 0.3 °C per decade — higher than the global average.

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