Warming, other factors worsened the floods in Pakistan, the study found

Warming, other factors worsened the floods in Pakistan, the study found

Climate change likely pushed rainfall as high as 50% late last month in two provinces in southern Pakistan, but global warming was not the main cause of the country’s catastrophic floods that killed more than 1,500 people, a new one finds. scientific analysis.

Pakistan’s overall vulnerability, including people living in danger, is the main factor in the disaster that at one point submerged a third of the country under water, but “man-made climate change also plays a very important role. here, “said study senior author Friederike Otto, a climate scientist at Imperial College London.

There are many ingredients for the ongoing humanitarian crisis: some meteorological, some economic, some social, some historical and building-oriented. Add to those weather records that don’t go far enough back in time.

With such complications and limitations, the team of international scientists looking into the disaster were unable to quantify how much climate change had increased the likelihood and frequency of flooding, the study authors said. He was released Thursday but not yet peer-reviewed.

What happened “would have been a disastrously high rainfall event without climate change, but it’s worse because of climate change,” Otto said. “And especially in this highly vulnerable region, small changes matter a lot.”

But other human factors that put people in danger and were not adequate to control water were even greater influences.

“This disaster was the result of a vulnerability that was built up over many, many years,” said study team member Ayesha Siddiqi of the University of Cambridge.

The August rainfall in the Sindh and Balochistan provinces – together nearly the size of Spain – was eight and nearly seven times the normal amount, while the country as a whole had three and a half times the normal rainfall, according to the report. World Weather Attribution, a collection of mostly volunteer scientists from around the world who carry out real-time studies of extreme weather conditions to look for the fingerprints of climate change.

The team only surveyed the two provinces in five days and saw an increase in rainfall intensity of up to 50%, likely due to climate change. They also surveyed the entire Indus region for two months and saw an increase in rainfall of up to 30%.

Scientists not only looked at records of past rains, which only date back to 1961, but used computer simulations to compare what happened last month with what would have happened in a world without heat-trapping gases from burning coal, oil. and natural gas. gas – and this difference is what they could attribute to climate change. This is a scientifically sound technique, according to the US National Academy of Sciences.

Study co-author Fahad Saeed, a climate scientist at climate analysis and the Center for Climate Change and Sustainable Development in Islamabad, Pakistan, said numerous factors have made this monsoon season much wetter than normal, including a La Nina, the natural cooling of part of the Pacific that alters the weather around the world.

But other factors were the signature of climate change, Saeed said. A bad heatwave in the region in early summer, made 30 times more likely due to climate change, increased the differential between land and water temperatures. That differential determines how much humidity goes from the ocean to the monsoon and means more of it drops.

And climate change seemed to change the jet stream, storm tracks and where the low pressure is slightly, bringing more rainfall to the southern provinces than they normally get, Saeed said.

“Pakistan hasn’t contributed much in terms of causing global climate change, but it certainly faces an enormous amount of climate change impacts,” said Jonathan Overpeck, dean of the environment at the University of Michigan, who was not a member. of study.

Overpeck and three other external climate scientists said the study makes sense and is adequately nuanced to include all risk factors.

Nuances help “avoid over-interpretation,” said Chris Field, a climate scientist at Stanford University. “But we also want to avoid missing the main message: man-made climate change is increasing the risks of extreme events around the world, including the devastating floods of 2022 in Pakistan.”


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