Indonesian President Joko Widodo's announcement that he wants to move the central government headquarters from Jakarta to the rainforest of Borneo sounds like a megalomaniac's fantasy. Widodo's justifications — easing the city's chronic congestion and better spreading the wealth among the country — make sense, however. Jakarta's greatest problem is not the overcrowding, though, but a rising sea level — and it is only one of many Asian cities experiencing this problem. Asian leaders, and their publics, and indeed coastal residents around the world, must begin preparing for a future marked by inundation.

Jakarta was founded in the 4th century in a marsh in Java as a key trading port and political center, and as Indonesia's capital ever since independence following the end of World War II. Today, it is a megacity of 10 million people; the population rises to 30 million when the entire metropolitan area is counted. (If current trends continue, it will surpass greater Tokyo as the world's most populous city by 2030, with an estimated population of 35.6 million people.)

The city's congestion is legion: Traffic jams absorb hours each day, robbing the country of productivity — losses are estimated at $7 billion annually — and contribute to a level of air pollution that is among the worst in Asia at times. The expanding population has led to the accelerated withdrawal of ground water, and as a result the city is sinking. Some 40 percent of the city is below sea level and experts believe that parts of the city are sinking 20 centimeters a year.