“People don’t want to hear it. If they get put in the flood zone, they think the maps are wrong”

Flooding will become the new normal during the 21st century, as sea levels rise and rainfall becomes more intense due to global warming, and cities sprawl along coasts and rivers.

Half a billion people are affected every year, and this could quadruple by 2050, according to the EU’s Global Flood Observatory. Reinsurance broker Aon Benfield has calculated that flooding was responsible for $27bn of economic losses in 2015, often in areas that never used to flood. That was a good year – the annual average loss over the last decade has been $48bn.

In this brilliantly illustrated cover feature for Modus, the magazine of the Royal Institution of Chartered Surveyors, I looked at how the economics of property will have to adapt to a much wetter world. By 2070, Kolkata and Mumbai will be the two cities whose populations will be most at risk, while Miami, Guangzhou, New York and Kolkata will have the most to lose in terms of assets.

Spending on flood protection is often targeted at the highest value land or assets, while the poorer the community, the less able it will be to recover from a disaster. One contributor warned of the creation of “flood ghettos”: “It’s not just the immediate flood area, it affects the surrounding areas, and the wider community drifts down the economic scale. It becomes a self-fulfilling prophecy of less investment and fewer opportunities.” Meanwhile, another flood surveyor is going back to college, to do a master’s degree in a rather different field: how adults learn. “Getting people to understand flood risk means changing their perceptions and logic,” he explains. “I’m intrigued by why people make choices that are not in their best interest.”

Set design by Hattie Newman, photography by John Ross