A new study led by the University of Graz indicates that climate change is likely to increase the frequency and intensity of persistent heavy rainfalls, particularly in northern Europe, Canada and East Asia, underscoring the urgent need for enhanced flood protection measures.
Extreme weather events are on the rise, driven by the mounting impacts of climate change. A pioneering study led by scientists at the Wegener Center for Climate and Global Change, University of Graz, has provided critical insights into how persistent heavy rainfall, known as cut-off lows, is expected to change as global temperatures continue to climb.
The study, published in the journal Communications Earth & Environment, underscores the increasing risk of flood events in regions north of 40 degrees latitude and in East Asia.
“We expect that persistent cut-off lows north of 40 degrees latitude and in East Asia will occur earlier in the year. Canada, northern Europe, Siberia and China in particular will have to prepare for more heavy and prolonged heavy rainfall in spring,” project leader Douglas Maraun, a professor of regional climate change at the Wegener Center for Climate and Global Change and leader of the Regional Climate Research Group, said in a news release.
A cut-off low is a type of low-pressure system that separates from the main polar front and often remains stationary for several days. This prolonged stasis can result in extended periods of intense precipitation, which has already been linked to devastating floods like those in the Ahr and Meuse valleys in 2021 and the recent deluge in Valencia, Spain.
Despite their potential for significant destruction, the behavior of cut-off lows under climate change has received limited scientific attention until now.
Working in collaboration with researchers from the University of Reading in the UK and the Institute of Atmospheric and Climate Sciences in Bologna, Italy, the team at the University of Graz embarked on the first in-depth analysis of these storms.
First author Aditya Mishra, who conducted the research as a doctoral candidate at the University of Graz and is now a postdoctoral researcher at Uppsala University in Sweden, explained their method.
“We analyzed 18 different climate models with regard to such storms,” he said in the news release. “To do this, we essentially read out weather maps from the models every six hours and used them to analyze the paths and intensity of such storms.”
The study’s findings reveal a troubling trend: these storms are likely to shift further north, with their season extending from summer and autumn into the spring. This expanded timeframe and geographical spread mean that regions unaccustomed to such climatic extremes may face an increased risk of severe flooding.
Environmental and infrastructural preparedness, such as flood protection, will be key to mitigating these risks.
“With targeted measures, such as renaturation and a functioning early warning system, we can at least partially protect ourselves from extreme weather and the impacts of climate change,” Maraun added.
This study represents a significant advancement in climate research, offering a clearer picture of how one aspect of extreme weather is expected to evolve. The insights provided by Maraun, Mishra and their colleagues could inform more effective flood mitigation strategies, enhancing resilience against the threats posed by a warming planet.