Copenhagen is becoming the world's first fully-fledged 'sponge city'

Hundreds of flood mitigation projects are being built across the city to protect against rising seas and heavy rains for the next 100 years. The sponge city concept originated in China. It deploys natural flood-protection measures such as parks, lakes and green roofs so urban areas can absorb excess water rather than succumb to flooding. These measures also boost biodiversity, improve air quality and help to keep temperatures down.