They are the worst floods that Pakistan has ever known. Tens of millions of people have already been evacuated, without any resources, and more than 1,200 people have died, while a third of the country is under water. The death toll is set to rise in the coming days, as for the moment the entire country is under water and the extent of the damage is still difficult to assess. But what caused such flooding ? According to researchers, it's a combination of climatic events that have set off a chain reaction, starting with global warming.
An extraordinary drought from April and May onwards
From April onwards, the temperature in Pakistan was well above the seasonal norm of around 30-35°C, and for several days exceeded 40°C in many places. Worse still, in the city of Jacobabad, the mercury a rose to 51°Cthe first of its kind in theNorthern hemisphere until this year! "These were not waves of heat normal, it was the worst in the world. We had the hottest place on Earth in Pakistan.explains Malik Amin Aslam in a press release from Natureformer Minister for Climate Change, based in Islamabad.
And these extreme heat waves do not bode well. L'air warmer, less dense air than cold air, can therefore retain more moisture. This stored water can then be released into the air.atmosphere once the rainy season had begun. As a result, above-normal rainfall levels were already forecast. What's more, the dryness of the air will naturally lead to a soil drought. These then become more compact, absorbing much less water than when they are inactive. weather soil. As a result, the water that reaches these soils tends to run off instead of infiltrating deep into the earth.
But the drought has also had other consequences. Visit high mountain glaciers in the north of the country melted, much more than usual due to the heat waves. Water was already flowing from the mountains into the Indus, the country's largest river, which crosses it from north to south, when the floods came. This river supplies towns and agricultural installations throughout Pakistan. And according to Zia Hashmi, a water resources engineer at Global Change Impact Studies Centreand flow rates high levels of muddy water in the Hunza river, which feeds the Indus, were observed in July. An observation that suggests a cast iron rapid and more intense than usual, and the possibility that some glacial lakes may have broken their dams.
Flooding so bad that a new lake has been created!
But that's not all! These floods also coincide with the arrival of an area of intense low-pressure in the Arabian Sea to the south of the country, causing heavy rainfall. heavy rains in Pakistan from June. "We rarely have large-scale depression systems happening out there".explains Athar Hussain, climatologist at the University of Islamabad. All these events, combined with a monsoon which started at the end of June helped to produce twice as much rainfall than average during the rainy season. Five times, in the southern provinces. So much so that a new lake has been created, even though the rains are now over!
This lake will recede once the weather dries up, but could well remain for a few days to a few weeks. Just like the water flowing across the country, which has already destroyed 240 bridges, 5,000 kilometres of roads and millions of homes. For this country, the worst is not yet over. Particularly representative of the effects of the global warmingIn a few years' time, such events could become the norm in Pakistan.
Text by futura-sciences.com
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