Millions of homes across London, Essex, and Kent face a growing risk of sinking into the ground, a phenomenon known as shrink-swell subsidence, according to new warnings from scientists at the British Geological Survey (BGS).
The BGS projects that if the world continues on its current emissions trajectory, over 1.8 million properties in the UK could be impacted by 2070. In London, which faces the most severe risk, up to 26 percent of homes could be affected within 45 years. Densely populated areas such as Camden, Islington, and Barnet are identified as particularly vulnerable.
Even under scenarios consistent with the Paris Agreement's green targets, the BGS predicts that 500,000 homes could still be affected by climate-related subsidence by 2070. A high-emissions scenario could see as many as 4.2 million properties nationwide and 54 percent of London homes affected.
Shrink-swell subsidence occurs when specific soil types expand as they absorb water during wet periods and contract when they dry out. This cyclical expansion and contraction causes the ground beneath buildings to shift, potentially dragging foundations downward. The South of England is especially susceptible due to its houses being built on young clay formations that readily absorb and release moisture in response to weather changes.
Anna Harrison, a scientist at the BGS, explained that combining geotechnical data on soil volume change potential with projected rainfall and temperature scenarios for the next century allowed researchers to pinpoint areas most at risk. "Dry weather and high temperatures are a major factor in the emergence of shrink-swell subsidence," Harrison stated. "Looking ahead, these increases in hotter, drier summers and warmer, wetter winters are projected to continue."
London is expected to experience significant changes in temperature and precipitation, presenting a "double whammy" of risks to the capital, according to Harrison. The BGS analysis highlights that while the overall number of affected homes may increase over the coming decades, many homeowners are already experiencing the impacts.
In the first six months of a recent year, subsidence-related insurance claims in the UK totaled £153 million, coinciding with the driest spring in over 50 years and the warmest recorded. Climate-related subsidence can diminish a property's value, and lenders may refuse mortgages on affected homes until issues are resolved. Repairs often involve expensive engineering work to stabilize the land or underpin the structure, and in extreme cases, may require replacing utility pipes or removing nearby trees.
Signs of subsidence can include diagonal cracks around doors and windows, and sloping floors. The BGS advises preventative action for homeowners whose properties are built on shrink-swell-prone clay. Recommended measures include installing impermeable drives or paths to limit water reaching the soil beneath the home, and exercising extreme caution with planting or removing trees near properties. Experts recommend consulting with specialists before undertaking significant building work or planting trees close to a house, and advise against removing mature trees that predate the building's construction without expert guidance.
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