from development and land reclamation can exacerbate subsidence in risk zones.79 Inadequate urban planning – for example, road developments that block natural groundwater recharge – can also contribute to land subsidence. Globally, it is estimated that 12% of soil compaction is attributed to urbanization.80 With nearly 58% of the world’s population currently living in cities – projected to rise to 68% by 2050 – the long-term implications of urban expansion on land stability warrant attention. Urbanization also drives increased water consumption for domestic purposes and across sectors. For example, the technology and manufacturing sectors use water for cooling and other uses. In areas prone to subsidence, heightened pressure on groundwater aquifers can intensify risks. Addressing these interconnected challenges requires coordinated approaches that consider both the physical environment, patterns of urban development and natural resource use. Climate change is a critical compounding factor driving land subsidence. While thermal expansion contributes to sea-level rise, the majority is driven by the melting of glaciers and ice sheets, linked to rising global temperatures from human action. Climate change also disrupts weather patterns, increasing the frequency and severity of tropical cyclones, extreme rainfall and storms, all of which amplify flooding in areas already experiencing land subsidence. Importantly, prolonged heatwaves and droughts can worsen subsidence. This can be due to a lack of rain to replenish underwater aquifers, overextraction of water to compensate for water storage and land erosion that occurs due to climate disruptions. Additional drivers include underground mining of other resources, other than water, hydrocarbon and geothermal extraction, hydro compaction and thawing permafrost. Each of these activities can destabilize subsurface layers, leading to ground instability and increased subsidence risk. Cities that fail to proactively manage these interconnected risks face escalating costs for drainage systems, infrastructure maintenance, urban planning and disaster response. Areas built on soft soils, reclaimed land or with excessive groundwater use, especially those also facing sea- level rise and extreme weather, are most at risk. While the specifics of subsidence vary by location, land and water use, and governance practices, the overarching trend is clear. Without sustainable management, cities, communities and economies will confront compounding challenges from sinking land and associated threats.12% of soil compaction is attributed to urbanization. Global land subsidence drivers FIGURE 3 GroundwaterUrbanization12%Tectonic9%Natural compaction 8%Mining 6%Geothermal 5%Oil and gas 55%4% Source: Huning, L. S., Love, C. A., Anjileli, H., et al. (2024). Global Land Subsidence: Impact of Climate Extremes and Human Activities. Reviews of Geophysics. https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2023RG000817. Resilient Economies: Strategies for Sinking Cities and Flood Risks 14

Resilient Economies Strategies for Sinking Cities and Flood Risks 2025