For many years, Jakarta appeared on demographic lists as a big city, but not at the top of the list. Its “official” population figures placed it somewhere around 30th place, among other fast-growing Asian metropolises. Suddenly, however, it found itself in first place. Not because it added millions of new residents overnight, but because the way we measure cities has changed.
Jakarta, a large metropolis with 42 million inhabitants
The latest UN estimates are no longer limited to narrow administrative boundaries, but consider the entire metropolitan area, the continuous urban body that extends beyond municipal and provincial boundaries. And they even include data on so-called “slums,” informal or semi-formal settlements that emerge near registered homes and administrative structures that have electricity, water, and sanitation.

Thus, Jakarta is no longer just a big city, but a large urban mass that includes suburbs such as Bogor, Depok, Tangerang and Bekasi. The result is impressive: about 42 million people live and move in this single urban system. And just like that, Jakarta “climbed” from 33rd place to first, more like a statistical discovery than a demographic miracle.
Paradoxical primacy and "weight"
Jakarta is not only the most populous city in the world. It is also a sinking city, literally. In some areas, the land is sinking at rates of up to 10, even 20 centimeters per year. Some neighborhoods, which two decades ago were comfortably above sea level, now regularly flood. Houses have sunk, streets have been “broken” into levels, walls have tilted. This is not a figment of the imagination or the alarmism of environmental organizations. It is a geological reality.

The main reason lies beneath the city’s feet. Jakarta is built on loose soil, the product of centuries of sediment deposition. Into this fragile substrate, the city has pumped vast amounts of groundwater for decades, mostly for industrial and domestic use. Uncontrolled pumping has depleted aquifers, the ground has been “disturbed,” and subsidence has become permanent. In a metropolis where many millions of residents have no reliable access to a drinking water network, private wells have acted as a slow self-destruction mechanism.
Adding to this geological instability is climate change. Jakarta is located in an area where heavy rainfall has always been a part of life. Today, however, the phenomena are more frequent and more extreme. Monsoons bring large volumes of water in a short time, rivers overflow, and the drainage system, already strained by urbanization, is unable to cope. When the land has already subsided and the sea is rising, any heavy rain becomes a threat.
Overpopulation makes everything worse
Its 42 million inhabitants are squeezed and built on every available piece of land, often without proper urban planning. What does this mean? Congested roads, rivers that have been “narrowed” by arbitrary construction, natural water outlets that have been lost. Jakarta grew quickly, unevenly and often haphazardly, following the logic of survival rather than a long-term plan.

Nusantara, the city under construction on the island of Borneo, is designed to replace Jakarta. The goal is to be fully functional as a center of government by 2028.
The Indonesian government is not ignoring the problem. In recent years, major flood protection projects have been launched, including dams, embankments, and a giant coastal project aimed at protecting the northern coastline from the sea. At the same time, efforts are being made to limit groundwater extraction and expand the water supply network so that residents do not have to “suck” the ground under their homes. However, the most radical solution is even more symbolic: moving the capital. Indonesia has already announced the construction of a new administrative capital on the island of Borneo, away from the sinking Jakarta. The new ultramodern capital, called Nusantara, has already begun construction, some services have been relocated, but it has by no means “replaced” Jakarta. This will take several years.

The goal is not only to save the country from a future catastrophe, but also to “relieve” the old capital of the millions of residents, civil servants and functions that currently suffocate it. Jakarta will not cease to be an economic and cultural center, but it will cease, in theory, to be the administrative nervous system of a country of 280 million people.
The question is whether time is enough. Jakarta continues to sink, floods continue to come, and its population, even if it stabilizes, remains large.
Its story, from “33rd place” to the top of the world list, is less a success story and more a wake-up call. A reminder that cities are not just numbers on the UN table, but living organisms, connected to their land, water and borders.