As the planet warms, thermal expansion of oceans and melting ice sheets are pushing global sea levels higher. In many coastal regions, sinking land from groundwater extraction and rapid development adds to the threat. But a new study in Nature Climate Change finds that in China, policy choices about where and how to develop coastal land may matter even more than climate change itself. The authors warn that policy uncertainties—whether cities expand into risky zones or adopt protective land-use strategies—could determine how many millions of people and how much infrastructure face flooding by 2100.

“Coastal populations and economies are expanding worldwide. With climate change and global politics so uncertain, it’s no surprise that future development policies remain highly unpredictable,” says WANG Yafei, associate professor at the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences and lead author of the study. “Understanding how these uncertainties interact with subsidence and rising seas to shape flood risk is a pressing scientific challenge.” 

For the first time, the researchers developed an integrated framework that combines three critical drivers of coastal flood risk: land-use policies (urbanisation, agriculture, ecosystem protection), climate factors (sea-level rise, storms, tides), and land subsidence. By linking high-resolution land-use data with policy scenarios and IPCC climate projections, the method provides a novel way to identify how policy decisions amplify—or reduce—future exposure. This integrated approach allows scientists to distinguish the physical extent of inundation from the social and political choices that determine who and what is most at risk.

The results highlight four hotspots of vulnerability: the Pearl, Yangtze, and Liaohe River deltas, and Bohai Bay—regions that are both low-lying and heavily urbanised. “These findings show that today’s choices on development, land management, and adaptation will shape the resilience of China’s coasts through 2100 and beyond,” WANG says. He cautions that seawalls and levees alone can create a false sense of security, encouraging riskier development—a “levee effect.” 

“Governments and local authorities have many tools to protect cities and communities from flooding. For example, by creating urban landscapes like parks that can be periodically flooded without harmful consequences and used for recreation when water levels are low. More broadly, spatial planning to avoid development in high-risk zones is important; and generally reducing carbon emissions is necessary to avoid accelerating sea-level rise, which could become the dominant risk factor beyond 2100, not just in China, but globally.” says Murray Scown, associate senior lecturer at Lund University Centre for Sustainability Studies, LUCSUS, and one of the authors of the study. 

This research is the product of a broad international collaboration between China and Europe. The study was led by WANG Yafei and Murray Scown, with important contributions from Ye Yuxuan, Robert J. Nicholls, Detlef P. van Vuuren, Lennart Olsson, Garry Peterson, He Yao, LI Manchun, and FAN Jie—spanning institutions in China, Sweden, the UK, and the Netherlands. The team hopes that the study can encourage the widespread use of integrated assessment models to analyse future flood exposure. This approach can identify which drivers are most important for managing risk, and how they interrelate. They can also help identify where power and agency to mitigate and manage risks lies.

Reference:

Wang, Y.F., Ye, Y., Nicholls, R. J., Olsson, L., van Vuuren, D., Peterson, G., He, Y., Li, M., Fan, J., Scown, M. (2025). Development policy affects coastal flood exposure in China more than sea-level rise, Nature Climate Change, 15. https://www.nature.com/articles/s41558-025-02439-2.

Policy brief:

Wang, Y.F., Ye, Y., Nicholls, R. J., Olsson, L., van Vuuren, D., Peterson, G., He, Y., Li, M., Fan, J., Scown, M. (2025). Managing development choices is essential to reduce coastal flood risk in China, Nature Climate Change, 15. https://doi.org/10.1038/s41558-025-02418-7.