It's a double whammy—vulnerable soil in the place changing fastest
Beneath the streets of London and across the clay-rich soils of southern England, a slow and largely invisible crisis is gathering force. As climate change drives hotter, drier summers, the ground itself is contracting — pulling foundations, cracking walls, and quietly undermining the financial security of millions of homeowners. The British Geological Survey has now mapped the scale of what lies ahead: under current emissions trajectories, more than 1.8 million UK properties could face climate-driven subsidence by 2070, a reckoning that is not a distant warning but an accelerating present.
- Subsidence claims already surpassed £153 million in the first half of 2025 alone — and the underlying conditions are only intensifying.
- London faces a compounding crisis: dense urban development sits atop clay soils uniquely prone to shrink-swell movement, and the capital will experience the sharpest climate shifts of any UK region.
- A property touched by subsidence can become unmortgageable overnight, threatening the single largest financial asset most British families will ever own.
- The gap between a low-emissions future and a business-as-usual trajectory is the difference between 500,000 and 1.8 million affected homes — a gap still being determined by global policy decisions made today.
- Scientists, lenders, and engineers are beginning to reckon with adaptation strategies, but the window for preparation is narrowing as record-dry springs signal that the future is already arriving.
A new British Geological Survey analysis has charted a troubling trajectory for British homeowners: as summers grow hotter and drier, the clay-rich soils beneath millions of homes will shrink, destabilising foundations and cracking the fabric of properties across southern England. The damage is not hypothetical — subsidence claims already exceeded £153 million in the first half of 2025 — but the full scale of the problem lies ahead.
The mechanism is both simple and relentless. Clay soils lose moisture during prolonged dry spells, contract, and pull foundations downward. Diagonal cracks appear around windows and doors, floors begin to slope, and what was solid becomes uncertain. Affected properties can become difficult or impossible to mortgage, and remediation — underpinning, pipe replacement, vegetation removal — is costly.
London carries a particular burden. The capital sits atop clay soils already prone to movement, will experience the most dramatic climate shifts of any UK region, and packs an extraordinary density of buildings into that vulnerable ground. Neighbourhoods including Camden, Islington, and Barnet face the sharpest exposure. Essex, Kent, and a broad corridor stretching northeast toward the Wash are also deeply at risk.
BGS scientist Anna Harrison described how the team layered soil composition data with century-long climate projections to produce a map of risk that darkens with each passing decade. Under a low-emissions scenario aligned with the Paris Agreement, around 500,000 properties could be affected by 2070. Under a medium scenario — closer to where current global trajectories are actually heading — that figure rises to more than 1.8 million, with more than a quarter of all London homes potentially impacted.
The 2025 spring was the UK's warmest on record and its driest in over fifty years. These are not anomalies but early signals of a pattern that climate science says will intensify. For millions of people whose homes represent their greatest financial security, the question is no longer whether subsidence will worsen, but how quickly — and whether adaptation can keep pace.
A new analysis from the British Geological Survey has mapped out a troubling future for millions of British homeowners. As the climate warms and summers grow hotter and drier, the soil beneath houses will shrink, pulling foundations down with it. The damage is already happening—in the first half of 2025 alone, subsidence claims topped £153 million—but the real reckoning lies ahead.
The mechanism is straightforward and relentless. Clay-rich soils, which underpin much of southern England, lose moisture during prolonged dry spells. As they dry out, they contract. Foundations that have sat stable for decades begin to move. Cracks appear diagonally around windows and doors. Floors slope. What was solid becomes uncertain. The property becomes difficult or impossible to mortgage. Fixing it requires expensive interventions: underpinning, utility pipe replacement, sometimes the removal of trees and vegetation that draw water from the soil.
The geography of vulnerability is already clear. London, Essex, Kent, and a broad band of land stretching from Oxford northeast to the Wash on England's east coast face the highest risk. But London bears the particular burden of a double exposure. The capital sits atop clay soils prone to shrink-swell subsidence, and it will also experience the most dramatic shifts in rainfall and temperature as the climate changes. Add to that the sheer density of buildings packed into the city, and the scale of the problem becomes apparent.
Anna Harrison, a scientist at the BGS, explained the convergence of factors: the team combined data on soil composition and its capacity for volume change with climate projections stretching a century forward. What emerged was a map of risk that grows darker with each passing decade. "These properties might have foundations that currently can withstand the changes in moisture," Harrison said, "but you might find in future there's going to be more movement. It's probably going to get worse."
The numbers tell the story. Under a low emissions scenario—one aligned with the Paris climate agreement and requiring dramatic global action—about 500,000 properties could be affected by 2070. But under a medium scenario, closer to where current global emissions trajectories are actually headed, that figure balloons to more than 1.8 million properties. In London itself, the impact could touch more than a quarter of all homes. Neighborhoods like Camden, Islington, and Barnet face particular exposure.
The timing is not distant. In 2025, the UK experienced its warmest spring on record and its driest in more than fifty years. These conditions are not anomalies but harbingers. The climate science is clear: hotter, drier summers will become more frequent over the coming century, interspersed with warmer, wetter winters. The ground will respond as it always has—shrinking when dry, swelling when wet—but the amplitude of those swings will increase, and the damage will accumulate.
For homeowners, the consequences are immediate and material. A property affected by subsidence loses value. Lenders grow cautious or refuse mortgages outright until the problem is resolved. The repairs themselves are not cheap. And for millions of people whose homes represent their largest financial asset, the prospect of that asset becoming unmortgageable or requiring six-figure stabilization work is not abstract. It is a threat to their security and their future. The question now is not whether subsidence will worsen, but how quickly, and what can be done to prepare.
Notable Quotes
These properties might have foundations that currently can withstand the changes in moisture, but you might find in future there's going to be more movement. It's probably going to get worse.— Anna Harrison, British Geological Survey
The Hearth Conversation Another angle on the story
Why does London face this risk more than other parts of the country?
It's a combination of geology and climate. London sits on clay soils that shrink significantly when they dry out. But the real problem is that London will also see the biggest changes in temperature and rainfall as the climate shifts. You're getting the most vulnerable soil in the place that's changing the fastest.
So this isn't just about hotter summers. It's about the pattern of wet and dry.
Exactly. The soil can handle gradual change. What damages it is the cycle—dry enough to shrink, then wet enough to swell, then dry again. As those swings get more extreme and more frequent, the foundation moves more. Eventually it cracks.
The numbers seem to jump dramatically between the low and high scenarios. Why such a difference?
Because emissions matter enormously. In a low scenario, we've cut global emissions sharply and limited warming. The climate still changes, but more slowly. In the medium scenario—which is basically where we're headed now—warming accelerates and the dry periods become more intense. That's the difference between 500,000 homes affected and 1.8 million.
What does it actually cost to fix a house with subsidence?
It varies wildly. You might need to underpin the foundation, which can run into the tens of thousands. You might need to replace pipes, remove trees, install drainage systems. And while you're doing it, the house is essentially unsellable. Banks won't lend on it. So it's not just the repair cost—it's the limbo.
Is there anything that can actually be done to prevent this?
Mitigation, yes. Better drainage around foundations, careful tree management, possibly different building standards going forward. But for the millions of homes already built on vulnerable soil, there's no prevention. Only adaptation and repair.