City planners defending against future coastal storms will have to contend with increasing rainfall driven by both climate change and urban buildup. But which is the more important factor?
New findings from researchers at Princeton and the South China University of Technology show that climate change and urbanization both play a role in storm-driven rain with the potential to lead to flooding and landslides. But the importance of each factor depends on how close the rain is to the city center.
“In the urban core, they are overall comparable,” said co-lead researcher Gabriele Villarini, a Princeton professor of civil and environmental engineering and the High Meadows Environmental Institute. “But as you go further out, the role of climate change becomes more predominant.”
In a Jan. 28 article in the journal Communications Earth & Environment, the researchers concluded that climate change has generally enhanced rainfall from tropical cyclones in coastal regions. Urbanization has exacerbated heavy rain in central city areas, potentially increasing the threat from surface runoff and flooding.
“For the cores of megacities, the exacerbation of heavy rainfall, and hence floods and inundations, by urbanization alone is likely greater than that by climate change alone,” the researchers write. “Our results of joint impacts of urbanization and climate change suggest that it is critical to quantify the role of both change agents toward a more realistic flood risk management.”
Previous research from Villarini’s group found that during Hurricane Harvey in 2017, Houston’s urban buildup contributed to heavier local rainfall—which caused devastating floods and over 100 deaths. The evidence demonstrates that buildings act as a drag on passing storms, Villarini said. This frictional urban landscape increases the time storms linger over the city. At the same time, tall buildings change the air flow and act like a vertical barrier that increases the amount of rain. Both effects combine over areas with dense building patterns.
“The rainfall footprint is different,” he said.
But were buildings the main cause of increasing rainfall, or was the increase driven by climate change? Villarini said a research team from Lawrence Berkeley National Laboratory also examined Hurricane Harvey and concluded that climate change played a significant role in the hurricane’s impact on Houston. Villarini said he wanted to better understand how each element fits together.
To find out, Villarini collaborated with Zifeng Deng and Zhaoli Wang at the South China University of Technology in analyzing ten major typhoons that hit the Pearl River Delta in China, a highly urbanized region, over the last two decades. Using high-resolution computer models, they simulated storms under different conditions—isolating the effects of climate change and urban development
The researchers concluded that climate change is responsible for changes in rainfall from tropical cyclones, and urbanization can shift the area in which the rain falls. Villarini characterized the study as a broad look at the phenomenon and noted that there are many variables that affect how a particular cyclone may develop and affect a coastal region. But he said the analysis suggests that urban planners should account for both climate change and the impacts of urbanization when adopting storm defenses.
The article, Climate change dominates over urbanization in tropical cyclone rainfall patterns, was published Jan 28 in the journal Communications Earth & Environment. The research was supported in part by the National Key R&D Program of China, the National Natural Science Foundation of China, the Natural Science Foundation of Guangdong Province and the China Scholarship Council. https://doi.org/10.1038/s43247-025-02048-z
