From China to Germany, floods expose climate vulnerability


The deadly floods that changed life in China and Germany were a stark reminder that climate change is making weather conditions more extreme around the world.

At least 25 people in central China’s Henan Province died Tuesday, including a dozen trapped in a city subway as waters ripped through the regional capital of Zhengzhou after days of torrential rain.

Coming after flooding killed at least 160 people in Germany and 31 others in Belgium last week, the disaster reinforced the message that significant changes must be made to prepare for similar events in the future.

“Governments must first realize that the infrastructure they have built in the past, or even recent ones, are vulnerable to these extreme weather events,” said Eduardo Araral, associate professor and co-director of the Institute. of Water Policy, to Lee Kuan Yew School of Public Policy.

In Europe, climate change is likely to increase the number of large, slow storms that can persist longer in an area and cause downpours of the type seen in Germany and Belgium, according to a study published on June 30 in the journal. Geophysical Research Letters. .

As the atmosphere warms with climate change, it also retains more moisture. This means that more rain is released when the rain clouds break.

By the end of the century, such slow storms could be 14 times more frequent, the researchers found in the study using computer simulations.

While the flooding that devastated vast swathes of western and southern Germany occurred thousands of miles from the events in Henan, both cases highlighted the vulnerability of densely populated areas to the catastrophic floods and other natural disasters.

“We need technical measures – strengthening dikes and flood barriers. But we also need to reshape cities, ”said Fred Hattermann of the Potsdam Institute for Climate Impact Research. He said the focus was increasingly on so-called “green adaptation” measures, such as polders and plains that can be flooded, to prevent water from flowing too quickly.

“But when there is really heavy rain, all of that may not help, so we have to learn to live with it,” he said.

Strengthening dikes and climate protection for housing, roads and urban infrastructure will cost billions. But dramatic cellphone footage of people struggling in subways submerged in chest-deep water in Zhengzhou, or crying in fear as mud and debris swept through medieval German cities, clearly showed the cost of do nothing.

“It’s shocking and I have to say it’s scary,” said John Butschkowski, a Red Cross driver who took part in rescue operations in western Germany this week. “It’s ghostly; no one anywhere, just garbage. And it is inconceivable that this will happen in Germany.

Koh Tieh-Yong, a meteorologist and climatologist at the University of Social Sciences of Singapore, said a comprehensive assessment of rivers and hydraulic systems would be needed in areas vulnerable to climate change, including cities and farmland.

“Flooding usually occurs due to two factors combined: one, more rainfall than normal and two, insufficient capacity of rivers to carry the extra rainwater collected,” he said.

In China and northwestern Europe, disasters followed a period of unusually heavy rains – equivalent in the Chinese case to a year of rain dumped in just three days – which completely overwhelmed flood defenses.

After several severe floods in recent decades, the buffer zones have been reinforced along major German rivers such as the Rhine or the Elbe. But last week’s extreme rainfall has also turned minor tributaries, like the Ahr or the Swist, into fearsome torrents.

In China, built-up urban areas with inadequate water drainage and large dams that altered the natural flow of the Yellow River basin may also have contributed to the disaster, scientists said.

But measures such as improving the resilience of buildings, raising banks and improving drainage are unlikely to be enough on their own to prevent the effects of severe flooding. As a last resort, warning systems – which have been heavily criticized in Germany for not allowing enough time to react – will need to be improved.

“It really has to be grounded in people’s working knowledge so that they know what to do,” said Christian Kuhlicke, head of a working group on environmental hazards and extreme events at the Helmholtz Center for Environmental Research.

“If you can’t hold the water, if you can’t save your buildings, at least make sure all the vulnerable people are moved out of these places.”

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