Not London, Tokyo or Istanbul – world’s largest mega-city has 42m people
- Jakarta, the capital of Indonesia, has been identified as the world's largest city, surpassing Tokyo in population size.
- The city's rapid growth has solidified its status as a global mega-city, but this expansion coincides with severe environmental threats.
- The sinking of Jakarta is driven by a combination of rising sea levels and land subsidence.
Jakarta, the capital of Indonesia, has been identified as the world’s largest city, surpassing Tokyo in population size. According to a United Nations report, the metropolitan area is now home to 41.9 million people, placing it ahead of Dhaka, Bangladesh, which has 36.6 million residents.
The city’s rapid growth has solidified its status as a global mega-city, but this expansion coincides with severe environmental threats. Jakarta is widely described as one of the fastest-sinking cities in the world, with large sections of the urban center facing the risk of being submerged.
Environmental and Infrastructure Challenges
The sinking of Jakarta is driven by a combination of rising sea levels and land subsidence. This subsidence is largely attributed to the excessive extraction of groundwater, which causes the land to compress and sink.
In coastal areas such as North Jakarta, the vulnerability to flooding has become acute. In some neighborhoods, concrete coastal walls are the only remaining barrier between residential and commercial properties and the encroaching sea.
The scale of the population growth has placed immense pressure on the city’s existing infrastructure, complicating efforts to implement large-scale flood mitigation and water management systems.
Regional Urbanization Trends
The rise of Jakarta reflects a broader demographic shift toward Asia. Data from the United Nations indicates that Asia is home to nine of the 10 most populous cities globally as of 2025.
While Tokyo previously held the title of the world’s largest city for an extended period, it has now fallen to third place in the global rankings. Jakarta’s ascent to the top spot underscores the acceleration of urbanization within the Indonesian archipelago and the wider Southeast Asian region.
The city is one of 19 megacities located across Asia, highlighting the concentration of human population in the region and the subsequent challenges regarding sustainable urban planning and climate resilience.