Miami’s beaches and boardwalks have become waterways. Houston’s highways looked like lakes just two weeks back, while halfway around the world boats were replacing buses as the streets of Mumbai were turned into rivers.

The scientific literature has a clear explanation for these dramatic images: global warming is bringing more rain and more floods, and is bound to leave certain cities — both on the coast and in river basins — particularly vulnerable. Back in June, Berlin, which sits on the Spree river faced a once-in-a-century meteorological event when heavy rains hit. According to the spokesperson of Berlin’s municipal water works, more than a quarter of the city’s average annual rainfall fell in the course of just 18 hours, German daily Die Zeit reported.

Cities have increasingly recognized the necessity of adapting to a wetter climate. Berlin authorities are set to adapt the city’s infrastructure to better handle increased rainfall with new techniques to transform buildings and green spaces into “sponges” with the ability to absorb large quantities of water over a short period of time. This will include planting rooftop gardens, creating more public parks, and installing swales. As another German daily Die Welt reports, the principle behind this movement is to move away from traditional practices of channeling water and toward draining systems.

The so-called “Sponge City” is not a German invention. The Chinese government first conceived the idea in 2013 and is now applying it in some 30 of its cities. Melbourne, Australia has invested heavily in a plan to build thousands of “raingardens” that will absorb excess precipitation and coastal flooding, while New Orleans has made the approach central to its latest rebuilding plans after Hurricane Katrina. “The objective isn’t just to protect yourself but to know the risks, accept them and adapt,” says Isabelle Thomas, an urban studies professor at the University of Montreal, told French daily Le Monde.

If successful, Sponge City practices are just one way to help reduce costs and even casualties as freak storms increasingly become the norm. The multi-billion-dollar investments are necessary to allow the globe’s metropolises to remain productive and profitable in the hope that the entire planet can begin to tackle the bigger challenge of reducing global warming. A sponge, after all, can only hold so much water.


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