Historic rainfall causes chaotic flooding on four continents

Heavy rains have lashed Central Europe, Africa, Shanghai and the US Carolinas this week, underscoring the extreme ways climate change is altering the weather.

Different weather phenomena are behind the series of storms, according to climate scientists, although they agree that a primary driver for the supercharged rainfall is global warming in general. Research has shown that hotter air is able to carry more moisture and is more likely to cause heavy precipitation.

And it’s not just the amount of rain that falls, it’s also where it lands. Emergency preparedness, infrastructure and access to aid funds have led to very different outcomes – a reminder that the effects of climate change are not felt equally in a warming world. At least 1,000 people have died in Africa and millions have been displaced. In Europe, meanwhile, the balance sheet is considerably smaller, and government officials have already pledged large amounts of public funding for reconstruction.

“There are these signatures of climate change in these heavy rainfalls that lead to these large floods,” said Hannah Cloke, professor of hydrology at the University of Reading. “But we have to recognize that humans have changed the landscape, they’ve made it more likely that humans will be in the path of these floods.”

Storm Boris, a slow-moving system, began unleashing torrential rain across Poland, the Czech Republic, Romania, Slovakia, Austria, Hungary and Germany last week. St Poelten, the capital of Lower Austria, recorded 409 millimeters (16 inches) of rain in five days, almost double the previous five-day record. More than 20 people died.

As rains recede in some areas, towns and villages are bracing for peak flooding in the coming days as the river swells. Several countries have already invested in control systems and holding tanks that help reduce some damage.

Heavy rainfall in the region can be traced back to the jet stream, a narrow, fast ribbon of winds in Earth’s upper atmosphere that travels from west to east. The jet stream is more orderly in the winter months, when cold air keeps its winds from moving away from the road. However, in the summer and early fall, the system tends to meander and “buckle,” sometimes becoming locked in masses or warm air.

Current radar and satellite images show that “the jet stream is clearly warped into large, sharp meanders, causing stagnant weather systems around the Northern Hemisphere,” said Jennifer Francis, a senior scientist at the Woodwell Climate Research Center with headquarters in Massachusetts. It’s not clear exactly what caused the jet stream to warp this season, she said, but “violent ocean heat waves” due to global warming were one culprit. Average sea surface temperatures were 0.96 C (1.73 F) above normal in August, the second warmest month on record.

Scientists also concluded that human-caused climate change exacerbated the heavy rains in Germany and Belgium that caused catastrophic flooding in 2021. A low that broke off from the jet stream dragged moisture from Mediterranean and slowly tore it into central Europe. . This resulted in Germany’s costliest disaster on record, racking up a bill of $40 billion. This time, Europe was better prepared, with forecasters predicting historic rainfall days in advance and giving communities time to prepare.

That was not the case in the US, where a historic storm – which Francis also attributed to the buckled jet stream – took Atlantic coastal communities by surprise on Monday evening. It unleashed record rainfall and tropical storm force winds of 50 miles per hour in North Carolina and South Carolina. Volunteers with rain gauges reported up to 18 inches of rainfall in 12 hours, according to the US National Weather Service, which would make it a once-in-a-millennium rain event.

The showers came from a weather system that formed over the Atlantic basin, but it ran out of track and failed to coalesce into a full hurricane or even a named storm before reaching the Carolina coast. Meteorologists at the National Hurricane Center were still referring to the system as “Potential Tropical Cyclone Eight” until it made landfall.

Despite historic rainfall, flooding was mostly confined to low-lying and coastal areas. “In many areas of the U.S., we’re seeing a clear trend toward more frequent and more intense heavy rain events, but we’re not seeing a commensurate increase in flooding,” said Ben Cook, a climatologist at the Goddard Institute for NASA. Space studies. “This is probably due to infrastructure development,” he said, and how vegetation changes or land surfaces dry out.

In West and Central Africa, the rains were driven by a distinct set of circumstances, with particularly deadly effects.

At least 2.9 million people have been displaced from the western and central Sahel and neighboring countries since record rainfall arrived in early September. The rains came during what is traditionally the monsoon season. But it was far too far too fast, with one forecaster predicting the region would see 500 percent of its average annual precipitation in September.

Friederike Otto, senior lecturer in climate science at Imperial College London, said the type of heavy rainfall experienced in Africa was “more likely due to fossil fuel-driven warming”. Earth’s average temperature is currently about 1.3 degrees Celsius higher than pre-industrial levels. This is consistent with warming trends in the Sahel, a semi-arid region that touches the southern Sahara desert and stretches across the continent from east to west.

Flooding has now affected at least 14 countries in the region, some of which were already struggling with food shortages and political instability. Heavy rainfall has destroyed cocoa plantations in Cameroon and disrupted grain production in Chad, where officials say thousands of animals have also drowned.

“We fear it will get worse, every year for the last four years the rains have become heavier, more violent,” said Mamane Hadi, a 36-year-old farmer from Zinder region in southern Niger, who is supposed to harvest crops, including dates. lettuce and squash this time of year. “Everything disappeared in the floods, there’s nothing left,” he said.

Meanwhile, China is bracing for another round of heavy rain in and around Shanghai after Typhoon Bebinca hit the city on Monday. It was the strongest storm to hit the financial center in more than 70 years, with winds so strong it would have qualified as a Category 1 hurricane.

Authorities have shut down transport links in the metropolis of 25 million and suspended food delivery services to keep drivers safe. Flights from Shanghai have been cancelled. Two people died, according to state media.

Bebinca was the latest in a parade of storms to hit China, Vietnam and Japan this year. On September 6, Super Typhoon Yagi slammed into the Chinese island of Hainan with winds of 144 miles per hour and caused flooding in Vietnam’s Mekong Delta, a significant rice-growing region.

The impacts were significant, even though this year’s western Pacific typhoon season could be considered milder than usual, according to AccuWeather meteorologist Jason Nicholls. Of 14 named storms this year, only six have reached typhoon strength.

Where the storms originate is more problematic for Pacific nations than the total number of storms. The Pacific Ocean is struggling to transition into its cooler La Niña phase, which pushes the starting point for typhoons and tropical storms farther west along the basin — and closer to population centers in Japan, the Philippines, China and Taiwan. Instead of turning poleward, several storm systems hit land before drifting out to sea.

Tropical Storm Pulasan has now emerged on much the same track as Bebinca, meaning more flooding in the waterlogged area around Shanghai, Nicholls said. Fortunately, Bebinca has stirred up cold water in the Pacific that will rob Pulasan of the fuel it needs to produce stronger winds. To the south, Tropical Depression 16 has developed in the South China Sea and will threaten Vietnam.

Many extreme weather events the world has seen in recent years have been worse than climate scientists predicted, according to Asher Minns, executive director of the Tyndall Center for Climate Change Research at the University of East Anglia. This trend is likely to continue as greenhouse gas emissions continue to rise and the planet continues to warm.

These catastrophic events are “kind of ahead of what global climate models and regional climate models would expect us to see,” Minns said. “It should be a little further in the future, but it’s happening now.”

Photo: Typhoon Yagi approaches on September 5, 2024 in Huizhou, China’s Guangdong Province. Photo credit: VCG/Getty Images

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