The intensity and extent of flooding in Germany this week shocked climatologists, who did not expect records to be broken so much, over such a large area or so soon.
After the deadly heat wave in the United States and Canada, where temperatures exceeded 49.6 ° C two weeks ago, the deluge in central Europe raised fears that man-made climatic disruptions could make conditions extreme weather even worse than expected.
Precipitation records were broken across a large area of the Rhine basin on Wednesday, with devastating consequences. At least 58 people have been killed, tens of thousands of homes flooded and the power supply cut off.
Parts of Rhineland-Palatinate and North Rhine-Westphalia were inundated with 148 liters of rain per square meter in 48 hours in a part of Germany that typically receives around 80 liters throughout the month of July.
The city of Hagen declared a state of emergency after the Volme overflowed and its waters reached unprecedented levels more than four times a century.
The most striking of more than a dozen records was fixed at Cologne-Stammheim station, which was inundated with 154mm of rain in 24 hours, erasing the city’s previous record of daily precipitation of 95mm.
Climatologists have long predicted that human emissions would cause more flooding, heat waves, droughts, storms and other forms of extreme weather, but the latest peaks have exceeded many expectations.
“I am surprised at how much above the previous record it is,” said Dieter Gerten, professor of climatology and hydrology of climate change at the Potsdam Institute for Climate Impact Research. “We appear to be not only above normal, but in areas we didn’t expect in terms of spatial extent and speed of development. “
Gerten, who grew up in a village in the affected area, said it was sometimes flooded, but not like this week. Previous summer showers have been just as heavy, but affected a smaller area, and previous winter storms have not raised rivers to such dangerous levels. “This week’s event is totally atypical for this region. It lasted a long time and affected a large area, ”he said.
Scientists will need more time to assess how much human emissions have made this storm more likely, but the record downpour is in line with broader global trends.
“With climate change, we expect all hydrometeorological extremes to become more extreme. What we have seen in Germany is broadly in line with this trend. said Carlo Buontempo, director of the Copernicus climate change service at the European Center for Medium-Range Weather Forecasts.
The hottest seven years in recorded history have occurred since 2014, in large part due to global warming, caused by engine exhaust, wildfires and other human activities. Computer models predict this will lead to more extreme weather conditions, which means records will be broken more frequently in more places.
The Americas have been the center of attention in recent weeks. The Canadian national daily heat record was surpassed by more than 5 ° C two weeks ago, as were several local records in Oregon and Washington. Scientists have said that these extremes at such latitudes are virtually impossible without human-induced warming. Last weekend, the Death Valley monitoring station in California recorded 54.4 ° C, which could turn out to be the highest temperature reliably recorded on Earth.
Daniel Swain, climatologist at the University of California at Los Angeles, said that so many records were set in the United States this summer that they were no longer in the news: “The extremes that would have been newsworthy there A few years are not, as they pale in comparison to the astonishing increases of a few weeks ago. It was happening in other countries as well, he said, but with less media attention. “The United States is often in the spotlight, but we have also seen episodes of extraordinary heat in Northern Europe and Siberia. It is not a localized abnormal event, it is definitely part of a coherent global model.
Lapland and parts of Siberia were also suffocated by record heat in June, and cities in India, Pakistan and Libya have experienced unusually high temperatures in recent weeks. The Tokyo suburbs were inundated with the heaviest rainfall since measurements began, and a usual month of July rain fell on London in one day. Events that have taken place every 100 years are becoming commonplace. The abnormal weather is more and more normal.
Some experts fear that the recent tremors indicate that the climate system may have crossed a dangerous threshold. Instead of a steady rise in temperatures and a steady rise in extremes, they examine whether the trend may be increasingly ‘non-linear’ or irregular due to the spillover effects of drought or melting. ice in the arctic. This theory is controversial, but recent events have sparked more discussion about this possibility and the reliability of models based on past observations.
“We need to better model nonlinear events,” Gerten said. “We scientists have been surprised in recent years by certain events which have occurred earlier and which have been more frequent and intense than expected. “