Megacities and Subsidence: Why 48 Cities Are Sinking Faster Than the Sea Is Rising

A danger that once felt remote is now compounding a quieter emergency: beneath many of the world’s megacities, the land surface is dropping year after year-centimetre by centimetre-shrinking the timeline for millions of people.

What scientists are warning about

A new paper in Nature Sustainability analysed 48 large cities where subsidence-slow, progressive ground lowering-is already under way. Together, these urban areas account for about one fifth of the global urban population. The findings are sobering: in certain neighbourhoods, the land is descending more quickly than sea levels are climbing.

In many coastal megacities, the land is sinking several times faster than the ocean is climbing, creating a double hit of risk.

This is not the sudden drama of a sinkhole or the shock of a major earthquake. Subsidence is typically gradual and uneven, arising from human pressures layered on top of local geology. Most urban systems-buildings, roads, buried utilities-assume the ground will remain largely stable. When that premise breaks down, whole districts begin to buckle and distort.

The cities sinking fastest

The study points to several urban hotspots where the problem is especially severe, either because the sinking is rapid or because vast populations are in harm’s way.

• Jakarta, Indonesia – up to 26 mm per year in some areas
• Ahmedabad, India – up to 23 mm per year
• Istanbul, Turkey – up to 19 mm per year
• Houston, Texas, USA – up to 17 mm per year
• Lagos, Nigeria – up to 17 mm per year
• Manila, Philippines – up to 17 mm per year

A few millimetres a year can look trivial on a chart. Project it across 30 or 40 years, factor in faster sea-level rise, stronger storms and swelling urban populations, and the risk profile escalates rapidly.

Jakarta: a sinking capital that gave up

Jakarta is the best-known case. In parts of the Indonesian capital, subsidence exceeds 26 mm a year, driven largely by unregulated groundwater pumping and the load of intensive development on soft, waterlogged ground.

In response, Indonesia has already made an extraordinary call: relocating the national capital roughly 1,000 kilometres away to a new location on the island of Borneo. That decision does not “save” the tens of millions who will still live in and around Jakarta, but it underlines how officials are judging the long-term prospects.

Relocating a capital city is less an act of ambition than an admission that some coastal risks can no longer be managed in place.

Mexico City: sinking far from the sea

Subsidence is not confined to the coastline. Mexico City-built over the sediments of an ancient lake-has long been sinking as clay-rich layers compact. For decades, groundwater extraction to supply a huge metropolitan population has effectively emptied those underground layers like a sponge, after which the structure collapses.

In some areas, roads deform, water pipes rupture and buildings lean at different angles. Engineers caution that even a total halt to pumping is unlikely to restore many zones, because the soils have already compressed into a near-permanent state.

Why these cities are going down

The immediate causes vary by location, but several recurring drivers appear across the study.

Main driver	How it makes cities sink	Typical examples
Groundwater extraction	Drawing water from underground aquifers leads the overlying soils to compact and settle.	Jakarta, Mexico City, Manila, parts of Houston
Weight of urban development	Dense buildings, roads and services push down on soft ground or reclaimed land.	Coastal districts of Jakarta, Lagos, Asian port cities
Sand mining and land reclamation	Removing or reworking sediments alters how the ground carries loads and supports structures.	Lagos, rapidly growing ports in West Africa and Asia
Oil and gas extraction	Extracting hydrocarbons can cause deeper layers to slump gradually over time.	Houston and parts of the Gulf Coast

How a city grows also matters. Where urban expansion is fast and informal, controls on well drilling, building loads and ground-movement monitoring are often weak or ignored. Under those conditions, subsidence rates can jump markedly within just 10 to 20 years.

Houston, Lagos, Manila: different cities, same direction

Houston’s petrochemical footprint

In Houston, subsidence is tied partly to oil and gas extraction, and also to heavy groundwater demand and industrial build-out along the Gulf Coast. Some low-lying suburban areas already depend on levees and drainage to keep tidal flooding out. As the land continues to sink, that buffer is undermined and the price of keeping infrastructure functional rises.

Lagos and the price of sand

Lagos-among the fastest-growing cities on the planet-faces a different trigger: widespread sand extraction. Sand is central to concrete production and to land-reclamation schemes. Removing it from coastal and lagoon systems can destabilise the terrain, leaving structures increasingly reliant on weak, shifting foundations.

With millions settling in informal communities on flood-prone ground, even modest additional sinking can turn seasonal high tides into frequent household crises.

Manila and the groundwater squeeze

In Manila, a mix of groundwater pumping, soft deltaic soils and rapid outward growth is contributing to subsidence reaching up to 17 mm a year in some districts. The Philippine capital already lies in the path of intense typhoons. When storm surges run over higher seas and meet a city that is physically lower, flood depths and repair bills climb sharply.

Subsidence doesn’t act alone; it amplifies every other coastal hazard that cities already struggle to manage.

Europe and France: slower, but not exempt

The research also flags parts of Europe-including France-as affected, although average rates are typically lower than those seen in many Asian or African megacities. Certain port areas and delta landscapes show measurable sinking, often associated with past land reclamation and groundwater use.

Slower movement does not automatically equal safety. Many European cities have extensive underground rail networks, ageing sewer systems and tightly packed historic centres. Even relatively small, uneven subsidence can distort tunnels, fracture masonry and compromise flood defences that were designed around very different expectations of ground stability and sea level.

Can anything actually stop this?

The authors’ message is clear: without major shifts, many of these cities are on track for partial or widespread inundation within decades. There is no universal solution, but there are practical steps that can reduce the pace of sinking or limit its consequences.

• Restricting or prohibiting unregulated groundwater pumping in high-risk areas
• Switching to lighter construction approaches and curbing ultra-heavy high-rises on soft soils
• Steering new development away from subsidence hotspots and flood-exposed coastlines
• Strengthening or redesigning sea walls, levees and drainage with ongoing ground lowering built into the calculations
• Tracking land motion via satellites so dangerous trajectories are detected early

Some interventions merely extend the window. A sea wall that works today may perform well for 20 years, then falter as sea level rises while the land surface drops. This tension is one reason some governments are weighing managed retreat from particular districts, even as they reinforce defences elsewhere.

What “inevitable disappearance” actually means

When researchers describe a city’s “disappearance” as inevitable, they are rarely predicting a single, cinematic moment when everything ends up underwater. More often, decline is uneven and prolonged.

Low-lying areas may first become difficult or impossible to insure. The cost of repairs and upgrades can exceed local finances. Better-off households may move to higher ground, while poorer communities are left in places that flood multiple times each year. Over decades, parts of a city can stop functioning in practice, even if the skyline still stands.

Disappearance often begins as a quiet retreat: bus routes cut, schools closed, maintenance skipped in streets that flood just a bit too often.

Key terms worth knowing

Subsidence is the slow lowering of the ground surface. It may happen naturally through geological processes, or be triggered by human activities such as pumping water, oil or gas from underground.

Managed retreat means a planned, deliberate move of people and infrastructure away from high-risk zones, rather than waiting for repeated disasters to drive hurried, uncoordinated evacuations.

A simple future scenario

Consider a coastal neighbourhood that currently sits 1 metre above high tide. If the land sinks by 15 mm per year and local sea level rises by 4 mm per year due to climate change, the combined relative shift is 19 mm annually. Over 30 years, the area’s effective elevation falls by more than half a metre.

Storm surges that were once considered “once in a century” could then occur every decade, or even every few years. Drainage built for rare floods would back up frequently. Buildings never intended to sit in salty water would begin to corrode from the ground up. Even without a single headline-grabbing disaster, daily life becomes steadily more difficult-and more expensive.

For many of the 48 cities assessed, that basic arithmetic leaves little room to wait. The ground is already moving, and it is moving in the wrong direction.