The Dutch are the acknowledged masters at living under the sea. About a third of the Netherlands lies below sea level. An elaborate set of dikes and pumps keeps the North Sea from rushing in.
But they’re not alone. A more accurate measurement of sea levels worldwide now shows some 110 million people live in areas below where normal high tides reach. The new study published this week in Nature Communications estimates that number could grow to between 190 million and 340 million by the end of the century, depending on how successfully carbon emissions can be curtailed.
The threat of sea-level rise will have ramifications around the world. Coastal farmers whose land disappears under the waves will have to migrate somewhere, probably to cities, to seek work.
Many urban areas already have begun bracing themselves for higher waters. But adaptation strategies such as building sea walls or gates often come with staggering costs. National governments may be reluctant or simply unable to finance these giant, long-term public works projects.
One financial strategy showing promise involves private investment. In some affluent areas, pushing back the sea using barriers could yield new land so valuable that it could be sold to pay for the project. In Copenhagen, Denmark, for example, a planned island reclaimed from the sea will include beaches and parks and, on its higher ground, some 35,000 homes as well as business areas. The government claims the cost will be entirely covered by charging to accept waste soil used in the project and by selling the new land.
In Singapore the prime minister has talked of similar land-creation plans that would be paid for, at least in part, by the value of the new property.
New York City is still recovering from being inundated by Superstorm Sandy in 2012. Earlier this year Mayor Bill de Blasio promoted the idea of extending the shoreline of lower Manhattan by as much as 500 feet into the East River – not only protecting Wall Street and other high-priced real estate but creating more of it.
If federal funding to help pay for the estimated $10 billion plan isn’t forthcoming, the mayor said he’s willing to seek out private developers.
Other less-costly and less-dramatic steps to mitigate rising seas are underway too. In some regions replanting mangrove forests can create an effective barrier against storm surges, along with providing other benefits.
As with other megacities, much of New York’s 580 miles of shoreline borders poorer neighborhoods where creating and selling land isn’t likely to make fiscal sense.
Create-and-sell schemes ought to be considered in places where they might work. But urban areas are still going to have to be creative and resourceful in finding other solutions to protect them against rising waters.