Sea-level rises are inevitable – and cities must prepare. Image: Reuters

The world’s coastal cities are going under. Here’s how some are fighting back

The warning signs are increasingly hard to ignore. Sea-level rise is real, displacing thousands of people, destroying millions of acres of land and generating billions of dollars in losses. Due to competing predictions of future global temperatures, scientists are unsure exactly how fast or high sea levels will rise.

But they all agree on its principle impacts: submergence and flooding of coastal land, saltwater intrusion into surface waters and groundwater, increased erosion and overwhelmingly negative social and economic repercussions. They are also emphatic that these effects will be widespread and will accelerate with time.

Rising temperatures, rising seas

The conservative scientific consensus is that a 1.5°C increase in global temperature will generate a global sea-level rise of between 1.7 and 3.2 feet by 2100. Even if we collectively manage to keep global temperatures from rising to 2°C, by 2050 at least 570 cities and some 800 million people will be exposed to rising seas and storm surges. And it is not just people and real estate that are at risk, but roads, railways, ports, underwater internet cables, farmland, sanitation and drinking water pipelines and reservoirs, and even mass transit systems. While some coastal cities and nations will literally disappear, the rest will need to adapt, and quickly.

A sizeable number of coastal cities have yet to adequately prepare for rising sea levels. This is dangerous. As the World Economic Forum's Global Risk Report 2019 shows, around 90% of all coastal areas will be affected to varying degrees. Some cities will experience sea-level rises as high as 30% above the global mean. Making matters worse, sprawling cities are sinking at the same time as sea waters seep in. This is due to the sheer weight of growing cities, combined with the groundwater extracted by their residents. In parts of Jakarta, a city of 9.6 million people, the ground has sunk 2.5 metres in less than a decade. Sea levels have simultaneously risen by 10 feet over the past 30 years.

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