"Climate change is bringing ever more precipitation and rising seas to low-lying Denmark. In response to troubling predictions, Copenhagen is enacting an ambitious plan to build hundreds of nature-based and engineered projects to soak up, store, and redistribute future floods."
"In just two hours on July 2, 2011, a torrential, once-in-a-millennium storm battered and flooded Copenhagen, pounding parts of Denmark’s capital with more than 5 inches of rain. Critical infrastructure at the city’s largest hospital was swamped, as were major roads, basements, and businesses. The city that had been engaged with advanced sustainability planning for decades, it turned out, was woefully unprepared for the fierce rainfall, which caused $1.8 billion in damages.
Shaken by the calamity, the city and its citizens grasped that such climate disasters — and deluges even more severe — were inevitable and required a rapid and strong response. To that end, Copenhagen brought together its top urban planners, landscapers, consultants, and architects to turn the city, which stretches across two main islands in the Baltic Sea, into the world’s first full-fledged “sponge city.” This state-of-the-art defense system — which combines nature-based surface features, like wetlands and parks, with large underground structures, like storage pipes and retention basins — is expected to fortify the city against cloudbursts and sea level rise for 100 years.
The intricately designed network manages stormwater and rising tides by soaking them up, storing them, and then slowly returning water to the water cycle. The sponge city build-out has been so successful that cities as disparate as Auckland, Nairobi, Singapore, New York, Rotterdam, and Berlin — and many others in the U.S. and Europe — now consider it an example to emulate."
Paul Hockenos reports for Yale Environment 360 July 28, 2025.
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