Jakarta, the centuries-old Indonesian capital, has one of the world’s highest rates of land subsidence, with some parts of the city sinking nearly 10 inches per year. Climate change is slowly leading to rising sea levels. It is a problem beyond the control of the city government. The more immediate threat is that much of Jakarta is sinking as the water table beneath the city is depleted. About 40 percent of Jakarta, including nearly all of the northern part of the city, is below sea level and that percentage will only continue to grow.
In response, the Indonesian government has introduced a “national coastal development” strategy, which includes plans to build a $30-billion, 300-mile-long seawall that would enclose Jakarta Bay. This is a quasi-temporary barrier to withstand rising sea levels and compensate for subsidence. It would be built extra high because, like other areas of north Jakarta, it is also expected to sink. At current levels, however, the coastal walls themselves may