What if bringing nature back to our gray cities could help us contain urban flooding? When architect Kongjian Yu first pitched this concept, he was celebrated in the West, but ignored in his native China. Until a devastating flood in 2012 hit Beijing and forced policymakers to give his green idea a chance. Today, the so-called sponge cities have revolutionised landscape architecture in China and serve as inspiration to some Western architects. In this video, we explore the genesis of Kongjian Yu's sponge cities, some of the architects applying this model on a global scale, and how efficient sponge cities are in the face of climate change.