What is the world’s most vulnerable city?

What is the world's most vulnerable city?
Malé, capital of the Maldives, stands only four feet above sea level // © Reinhard Krause

From the Maldives to Mauritania, some cities are engaged in a constant battle for survival against nature’s relentless forces. But which of these metropolises is closest to being overwhelmed by sea, sand or other natural threat?

Setting aside epic disaster-movie moments such as volcanoes, hurricanes and earthquakes, there are two key natural factors that can make a city vulnerable to gradual disintegration, or even total disappearance – water and sand.

Were climate change making the planet colder rather than hotter, we could add ice to the list – for nothing obliterates a city like a billion-tonne glacier grinding its way down a valley. The impact of a rare “ice tsunami” in 2013 on the Canadian municipality of Ochre Beach was just a taster: a wall of melting iceberg on Dauphin Lake was blown by winds on to the shore, splintering every house in its path.

But Ochre Beach was an anomaly. Elsewhere the planet’s melting ice is making cities vulnerable by the less dramatic route of raising sea levels. A century ago Venice – one of the most beautiful and low-lying cities in the world – used to flood around 10 times a year. Nowadays its lowest point, Piazza San Marco (only three feet above sea level) is inundated with water approximately 100 times annually.

But rising sea levels are not entirely to blame. In many parts of the world, the land is also sinking – in Venice’s case, subsoil compaction (a result of industrial exploitation of the surrounding area) lowered the city by 20cm between 1950 and 1970. []