ROME — The floods that sent rivers of mud tearing through towns in Italy’s northeast are another drenching dose of climate change’s all-or-nothing weather extremes, something that has been happening around the globe, scientists say.
The coastal region of Emilia-Romagna was twice struck, first by heavy rain two weeks ago on drought-parched ground that could not absorb it, overflowing riverbanks overnight, followed by this week’s deluge that killed 13 and caused billions in damages.
In a changing climate, more rain is coming, but it’s falling on fewer days in less useful and more dangerous downpours.
The hard-hit Emilia-Romagna region was particularly vulnerable. Its location between the Apennine mountains and the Adriatic Sea trapped the weather system this week that dumped half the average annual amount of rain in 36 hours.
Antonello Pasini, a climate scientist at Italy’s National Research Council, said a trend has been establishing itself: “An increase in rainfall overall per year, for example, but a decrease in the number of rainy days and an increase in the intensity of the rain in those few days when it rains,” he said.
Italy’s north has been parched by two years of drought, thanks to less-than-average snowfall during the winter months. The melting snow of the Alps and Dolomites, and the Apennines, normally provide the constant runoff throughout spring and summer, which fills Italy’s lakes and irrigates its agricultural heartland. also keeps the Po, and other important rivers, flowing ..
Without that normal snowfall in the mountains, plains have gone dry and riverbeds, lakes and reservoirs have receded. They cannot recover even when it rains because the ground is essentially “impermeable” and the rain just washes over the topsoil and out to the sea, Pasini said.
” “So, these extreme rains do not compensate for the drought,” he explained, because in northern Italy the drought relies more on the snow that is stored in the Alps rather than rain. And in the last two years, we have had very little snow.”
Civil Protection Minister Nello Musumeci said the new normal of extreme weather events in the Mediterranean requires Italians to adapt and Italy to rethink its flood protections nationwide. He cited a fierce storm-triggered landslide last fall on the southern island of Ischia, off Naples, that left 12 dead.
“We cannot pretend nothing is going on,” said he Thursday. “Everything must change: the programming in hydraulic infrastructures must change, the engineering approach must change.”
He said those changes are necessary to prevent the types of floods that have left entire towns swamped with mud after two dozen rivers burst their banks.
The key going forward is prevention, he said, acknowledging that’s not an easy sell due to costs.
“We do not tend to prevent. We like to rebuild more than to prevent,” he told Sky TG24.
Italy’s experience of a sudden change from drought to flood is not unique. California and the United States West sloshed its way from a record-setting megadrought to at least a dozen atmospheric rivers dousing the state with so much rain that a long-dormant lake reappeared.
“The wettest places are getting drier,” Princeton University Climate Scientist Gabe Vecchi stated Thursday.
In 2021, the United Nations’ Intergovernmental Panel on Climate Change scientific panel said it was “established fact” that humans’ greenhouse gas emissions had made for more frequent and intense weather extremes. Heat waves were the panel’s top priority, but heavy rainfall events have also increased in most parts of the globe.
The U.N. report said “there is robust evidence” that record rainfall and one-in-five, one-in-ten and one-in-twenty year type rainfall “became more common since the 1950s.”
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Borenstein contributed form Kensington, Maryland.
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