Nature-based solutions are designed to use ecological processes to address urban problems. A restored wetland can temporarily store stormwater, vegetation can cool overheated streets through shade and evapotranspiration, and permeable landscapes can help rainfall infiltrate soil rather than overwhelm drainage systems. In principle, these approaches offer multiple benefits at once: climate adaptation, improved public space, habitat creation, and better air quality. In practice, however, urban land is contested, infrastructure is fragmented, and investments must compete with housing, transport, commercial development, and other public priorities.

The researchers—Sofia Khromova, Svenja Busse, Giulia Benati, and colleagues—focused on a central question: how can cities identify locations where nature-based solutions are both urgently needed and realistically deliverable? Their cross-city approach examines Barcelona, Boston, and Rotterdam, three cities with distinct climates, landscapes, planning traditions, and exposure to environmental hazards. Comparing them allows the study to move beyond a single-city case study and explore whether a common planning logic can be applied across different urban contexts without ignoring local conditions.

The concept of risk in this framework includes the hazards that nature-based solutions are intended to reduce. These may include extreme heat, surface-water flooding, coastal or river flooding, drought stress, and other climate-related pressures. Risk can be mapped spatially by combining information about the probability or intensity of a hazard with the people, buildings, infrastructure, and services exposed to it. A neighborhood with frequent flooding and a high concentration of residents, schools, or critical facilities would therefore be treated differently from an undeveloped area facing the same rainfall pattern.

Feasibility introduces a second layer of analysis. A site may face severe climate risk but still be difficult to transform because land ownership is divided, underground utilities limit construction, soil conditions are unsuitable, or regulations restrict changes to the public realm. Maintenance capacity, available funding, public acceptance, and competition for land can also determine whether a proposed intervention moves beyond a map and becomes a functioning urban project. By bringing these constraints into the same spatial assessment as environmental risk, the study addresses a common weakness in climate planning: identifying places that need action without determining whether action is possible.

This distinction is particularly important because nature-based solutions are not interchangeable. A street tree system requires sufficient soil volume, irrigation or water access during establishment, and protection from compaction. A rain garden needs a design that can receive runoff while allowing water to infiltrate safely. A green roof depends on the structural capacity of a building, appropriate waterproofing, and long-term maintenance. A wetland or floodable park requires space, hydrological connectivity, and governance arrangements capable of managing changing water levels. Spatial planning must therefore connect the type of intervention with the physical and institutional characteristics of each location.

Barcelona, Boston, and Rotterdam provide a revealing comparison because their urban risks and opportunities differ sharply. Barcelona faces intense heat and water stress within a dense Mediterranean setting where open land is limited. Boston must consider heat, precipitation, coastal exposure, and the legacy of highly developed waterfront areas. Rotterdam, shaped by its low-lying geography and extensive relationship with water, presents a different combination of flood risk, drainage needs, and opportunities for water-sensitive urban design. The study’s cross-city perspective emphasizes that a method developed in one location cannot simply be copied elsewhere without recalibrating its risk indicators, land-use assumptions, and implementation conditions.

The research also highlights a deeper planning challenge: high-risk areas are not always high-feasibility areas. The places most exposed to climate hazards may be the most densely built, socially vulnerable, or economically valuable parts of a city. These areas can have the greatest need for cooling, stormwater management, or flood protection, while simultaneously offering the least available space and the most complicated construction conditions. Conversely, sites that are easy to convert may be located where risks are lower or where fewer people would benefit. A useful planning strategy must therefore identify trade-offs rather than treating feasibility as a simple yes-or-no filter.

By integrating the two dimensions, the analysis can support more targeted decisions. Locations with high risk and high feasibility may represent near-term priorities, where a city can deliver measurable benefits with comparatively fewer obstacles. High-risk but low-feasibility areas may require long-term redevelopment strategies, regulatory changes, land acquisition, or coordination with infrastructure upgrades. Lower-risk sites with strong feasibility could still serve as demonstration projects, ecological corridors, or components of a wider network. This type of prioritization can help planners move from broad ambitions—such as increasing urban greenery—to a sequence of actions connected to risk reduction and implementation capacity.

The study’s significance extends beyond the three cities examined. As extreme weather intensifies and urban populations grow, municipalities are under pressure to make climate investments that are effective, equitable, and defensible. Mapping risk alone can produce plans that look compelling but stall during implementation. Mapping feasibility alone can favor convenient projects while leaving vulnerable communities underserved. The research instead presents nature-based urban planning as a multi-criteria problem requiring environmental data, engineering knowledge, land-use analysis, governance information, and public decision-making to work together.

That integrated perspective could also influence how cities evaluate success. A park or green corridor should not be judged only by its area, visual appeal, or contribution to urban biodiversity. Its performance may depend on whether it reduces peak runoff, lowers local temperatures, protects vulnerable residents, connects fragmented habitats, or remains functional during extreme events. At the same time, benefits can be unevenly distributed, and improvements in one neighborhood can produce unintended consequences elsewhere if they increase land values or accelerate displacement. Risk and feasibility assessments therefore need to be linked with questions of access, social vulnerability, maintenance responsibility, and long-term accountability.

The cross-city analysis ultimately turns a popular climate solution into a more demanding planning question: where can nature do the most work, and where can cities realistically support it? Barcelona, Boston, and Rotterdam show why the answer cannot be reduced to a universal formula. Nature-based solutions perform best when their ecological functions are matched to local hazards, urban form, available land, technical requirements, and institutional capacity. As the findings enter the growing debate over climate-resilient cities, their central message is clear: the future of urban nature will depend not only on how much green infrastructure cities plan, but on how intelligently they connect risk, place, and the practical conditions required to make those plans endure.

Subject of Research: Spatial planning of nature-based solutions, integrating urban environmental risk and implementation feasibility across Barcelona, Boston, and Rotterdam.

Article Title: Integrating risk and feasibility in the spatial planning of nature-based solutions: a cross-city analysis of Barcelona, Boston, and Rotterdam

Article References: Khromova, S., Busse, S., Benati, G. et al. “Integrating risk and feasibility in the spatial planning of nature-based solutions: a cross-city analysis of Barcelona, Boston, and Rotterdam.” npj Urban Sustainability (2026). https://doi.org/10.1038/s42949-026-00461-7

Image Credits: AI Generated

DOI: 10.1038/s42949-026-00461-7

Urban soil rehabilitation entails restoring the physical, chemical, and biological properties of soil to revive its capacity to support ecosystem services such as climate regulation, water infiltration, and biodiversity habitat. The research underlines that these services underpin urban resilience, helping cities mitigate prevalent challenges such as flooding and urban heat islands. Compacted soils, which lose their porosity and permeability, lead to increased runoff and flooding risks during heavy rains, while sealed soils—surfaces covered by impermeable materials like asphalt or concrete—disconnect soil from natural cycles entirely. Polluted soils further complicate urban sustainability by introducing contaminants that impair ecosystem and human health alike.

The French study quantifies median rehabilitation costs, revealing striking financial disparities depending on soil conditions and contamination levels. For soils affected solely by compaction or sealing, costs range between €50 and €310 per square meter. However, when pollution remediation becomes necessary, expenses surge dramatically to exceed €800 per square meter. These figures emphasize that urban soil rehabilitation is not a uniform or straightforward process. Instead, it involves multiple phases and varied techniques tailored to the specific degradation type and local context, which inevitably impacts cost structures.

At the core of urban soil rehabilitation is a systematic sequence of up to ten distinct steps, each critical to achieving successful restoration outcomes. These sequential phases begin with preliminary analyses — extensive pre-intervention diagnostics that evaluate soil conditions through chemical, physical, and biological assessments. Though these diagnostics represent the least expensive step in the rehabilitation process, they are indispensable. Such analyses inform technical choices, ensuring that resource allocation targets soil challenges effectively. Skipping or minimizing this phase risks ineffective interventions that inflate costs and diminish ecological benefits.

On the other end of the cost spectrum are construction deconstruction and pollution remediation. Deconstruction involves the careful dismantling of built infrastructure to access underlying soils. This phase is labor-intensive and technically demanding, especially in densely built urban centers, contributing significantly to overall expenses. Pollution remediation adds further complexity and cost, as it requires specialized techniques to remove or neutralize chemical contaminants. The financial escalation linked to contaminated soils demonstrates the intricate nature of environmental restoration within urban environments, where legacy pollutants often linger in layers beneath the surface.

This comprehensive financial overview not only frames the economic hurdles of urban soil rehabilitation but also serves as a strategic tool to prioritize intervention areas. By understanding where costs spike, city planners can weigh the ecological benefits against economic inputs, directing funding toward projects with the greatest impact on resilience and sustainability. Moreover, these insights can inform the design of economic incentives, such as subsidies or tax relief for developers and stakeholders engaged in soil rehabilitation — fostering a market environment where healthy urban soils are valued alongside built infrastructure.

The urgency of maintaining urban soil health extends beyond rehabilitation efforts. The study accentuates the critical importance of preserving existing healthy soils to minimize the need for costly restoration interventions. Urban expansion often accelerates soil degradation, hence proactive protection strategies could yield significant savings while safeguarding ecosystem services. Integrative urban design practices that incorporate permeable surfaces, green infrastructure, and controlled construction can help achieve this balance, ensuring urban growth does not come at the irreversible expense of soil vitality.

Moreover, urban soil rehabilitation intersects with global climate goals. Healthy urban soils contribute to carbon sequestration, helping cities mitigate greenhouse gas emissions and adapt to climate change impacts. Their ability to regulate microclimates through enhanced evapotranspiration and heat buffering reduces urban heat island effects—an increasingly critical service amid rising global temperatures. Therefore, investing in soil rehabilitation aligns with broader environmental policies targeting climate resilience and sustainable urban living.

It is also noteworthy that urban soils play a pivotal role in supporting biodiversity within cities at multiple scales. From microbial communities in the soil horizon to larger invertebrates and plant systems, healthy soils sustain the urban green spaces that offer habitat connectivity and ecological corridors. Soil rehabilitation efforts thus hold potential co-benefits, aiding urban ecological networks and enhancing citizens’ interactions with nature, which positively influences well-being and livability.

The technical developments underlying urban soil rehabilitation are evolving. Advances in remediation techniques—ranging from phytoremediation using plants to extract contaminants to bioremediation harnessing microbial processes—offer scalable and innovative approaches to pollution management. Modern deconstruction methods now emphasize minimal environmental disturbance coupled with material recovery and reuse, reflecting circular economy principles. Together, these engineering and biotechnological innovations shape the feasibility and efficiency of urban soil restoration projects.

Public and private sector collaboration emerges as a necessary dynamic for advancing urban soil rehabilitation at scale. Given the financial burden outlined by this recent research, partnerships that leverage expertise, shared funding, and policy support can catalyze comprehensive soil recovery programs. Cities might consider integrated management frameworks coupling land use planning with ecological restoration, aligning regulatory incentives with sustainability targets to maximize impact.

Finally, this new economic clarity also influences urban resilience thinking, which traditionally emphasizes infrastructure and emergency response readiness. Soil health, often overlooked, is now illuminated as a foundational resilience element warranting dedicated investment. Future urban resilience strategies should integrate soil rehabilitation with complementary efforts such as stormwater management, green roofing, and urban forestry, creating multifunctional landscapes that simultaneously address environmental, social, and economic challenges.

In summary, the French study not only brings much-needed attention to the costs and complexities of urban soil rehabilitation but also reframes soil as a vital urban resource. Recognizing that healthy soils underpin critical ecosystem services essential for climate adaptation and disaster risk reduction establishes soil rehabilitation as a strategic priority within the urban sustainability agenda. As global urbanization continues unabated, understanding and investing in soil restoration offers a pathway toward greener, more resilient, and economically viable cities.

The findings also highlight significant disparities in rehabilitation expenses depending on soil condition states, guiding targeted intervention prioritization. The delineation of the sequential rehabilitation steps provides a practical framework for future projects and policymaking. Elevating soil health within urban planning discourses facilitates a shift from reactive remediation to proactive preservation, ensuring sustainable urban ecosystems endure and flourish.

In an era when cities are on the frontline of climate impacts and ecological pressures, this research delivers a pivotal message: urban soil rehabilitation is not merely an environmental task but a complex socio-economic undertaking that demands innovative governance and committed investment. Through understanding these costs and mechanisms deeply, stakeholders can forge resilient urban futures where soils regain their fundamental roles, benefiting ecosystems and human societies alike.

As a beacon for future exploration, this comprehensive assessment of costs lays the groundwork for further research integrating social, ecological, and economic dimensions of urban soil health. It encourages multidisciplinary collaboration to develop inclusive strategies addressing equity in soil restoration benefits, ensuring all urban communities share in the advantages of revitalized ecosystems. With such integrative efforts, urban soil rehabilitation can become a cornerstone of sustainable city development worldwide.

Subject of Research: Economic analysis and cost estimation of urban soil rehabilitation, focusing on the restoration of soil ecosystem functions compromised by urbanization impacts such as compaction, sealing, and pollution.

Article Title: Digging into the costs of urban soil rehabilitation

Article References:
Salin, M., Claron, C., Nguyen–Rabot, E. et al. Digging into the costs of urban soil rehabilitation. Nat Cities (2026). https://doi.org/10.1038/s44284-026-00452-w

Image Credits: AI Generated

DOI: https://doi.org/10.1038/s44284-026-00452-w