Altenahr, a town in Altenburg, Germany, was almost completely submerged by flooding caused by the July 2021 storm. Credit: Martin Seifert
Climate change gets all the attention when it comes to extreme weather. According to a study from The University of Texas at Austin and two universities in China, the unique effects of cities need to be accounted for.
The effects of urbanization are part of the solution, according to a professor in the UT Jackson School of Geosciences.
Niyogi is a co-author on a study that used computer models to investigate how cities and climate change influenced the rainstorm that struck the Rotterdam-Brussels-Cologne metropolitan region on July 14, 2021.
The model found that the interplay of large-scale climate and local-scale urbanization made the storm more severe.
In the summer of 2021, a storm system that included a severe weather system and heavy rain caused flooding that killed at least 241 people, making it one of the deadliest floods in European history.
Scientists from Tsinghua University were on the research team.
Local climate and storms can be impacted by urbanization. Storm systems can stall because of the taller and closer buildings in the city. Higher levels of pollution and warmer temperatures can increase the amount of water in the clouds.
The interplay between a warmer climate and city environment led to a 50% increase in the amount of rain in suburban areas. Three inches of the 6 inches of rain that fell on the metropolitan region on July 14 can be attributed to these interactions.
The scientists created a storm computer model that included the effects of the environment, city and climate. The model was representative of the actual event. The simulation shows the storm centered over eastern Belgium and western Germany and unfolded over the same time period with the most rain falling on July 14. The total amount of rain that fell was overstated by 7.2 inches by the model.
The researchers created simulation models that replaced cities with land and lowered the temperatures to pre-industrial levels. The researchers were able to determine how cities and climate influenced the storm by doing this.
The influence of the climate and the city together had the greatest impact, but the influence of the city alone is more significant than the change in climate, according to the lead author.
The impacts of land-atmosphere interactions on extreme rainfall are comparable to those of climate-scale processes.
One extreme storm is applied to the models. Niyogi said that the results conform with different urban rainfall studies and show the importance of incorporating the influence of urbanization and regional landscapes into climate models in general.
He said that adapting to climate change gives an opportunity to plan more resilient communities that can help shape desired climate outcomes, such as cities that can send storms away from flood-prone regions.
Niyogi said that there are immediate ways to develop climate resilience at local scales. "It's something you can do at the city scale."
The study's additional co-authors are professors from Tsinghua University in China.
Long Yang et al., urbanization exaggerated rain over European suburbs under a warming climate, was published in a research letter. The DOI is 10.1029/2021GL095987.
The journal contains information about research.
Cities boosted rain, sent storms to the suburbs during Europe's deadly summer floods.
The document is copyrighted. Any fair dealing for the purpose of private study or research cannot be reproduced without written permission. The content is not intended to be used for anything other than information purposes.
