Interview: practitioners on Nature-based solutions — what they wish they knew earlier

The European Union committed €8 billion to nature-based solutions (NbS) between 2021 and 2027 under its biodiversity strategy, yet practitioners report that fewer than 35% of projects achieve their stated climate adaptation targets within the first five years. This gap between ambition and execution has prompted a new generation of sustainability leaders to rethink how they measure success, structure investments, and communicate value to stakeholders.

We spoke with project managers, urban planners, corporate sustainability officers, and investment analysts across the EU to understand what separates high-performing NbS initiatives from those that struggle. Their insights reveal that success hinges not on the scale of investment, but on selecting the right KPIs, establishing realistic benchmark ranges, and maintaining adaptive management frameworks throughout project lifecycles.

Why It Matters

Nature-based solutions represent one of the most cost-effective strategies for addressing the interconnected crises of climate change, biodiversity loss, and urban heat stress. The European Environment Agency estimates that NbS interventions deliver ecosystem services valued at €26 billion annually across the EU, including flood mitigation, carbon sequestration, air quality improvement, and temperature regulation.

The urgency has intensified dramatically. In 2024, Europe experienced its hottest summer on record, with heat-related mortality exceeding 70,000 deaths across the continent. Urban areas bore the brunt, with surface temperatures in cities like Madrid, Rome, and Athens exceeding 50°C during peak events. Municipal governments are now accelerating NbS deployment, with the European Green Deal allocating €25 billion specifically for urban greening and ecosystem restoration through 2030.

From a regulatory perspective, the EU Taxonomy now classifies certain NbS investments as sustainable economic activities, creating new compliance pathways for financial institutions and corporates seeking to meet disclosure requirements under the Corporate Sustainability Reporting Directive (CSRD). By 2025, an estimated 50,000 European companies will need to report on climate adaptation measures, making NbS tracking and verification a mainstream business concern.

The economic case has become compelling. Research published in Nature Climate Change (2024) demonstrates that every €1 invested in urban green infrastructure generates €4.20 in avoided healthcare costs, reduced energy consumption, and property value appreciation. For corporate real estate portfolios, NbS implementations have shown 12-18% reductions in cooling CAPEX over 10-year horizons.

Key Concepts

Understanding nature-based solutions requires familiarity with several technical terms that practitioners use daily:

CAPEX (Capital Expenditure): The upfront investment required to design, construct, and establish NbS interventions. For urban forestry projects, CAPEX typically ranges from €150-400 per tree installed, including soil preparation, irrigation systems, and three-year establishment care. Practitioners emphasize that underestimating CAPEX leads to inadequate maintenance budgets and higher long-term failure rates.

Heat Stress Mitigation: The capacity of vegetated systems to reduce ambient and surface temperatures through evapotranspiration and shading. A well-designed urban park can lower surrounding air temperatures by 2-4°C during peak summer conditions. The benchmark for "good" performance is achieving >3°C reduction within a 200-meter radius of the intervention.

Critical Infrastructure Protection: NbS applications that safeguard essential systems—transportation networks, energy grids, water treatment facilities—from climate hazards. Coastal wetland restoration, for example, can reduce wave energy by 60-80%, protecting infrastructure that would otherwise require €2-5 million per kilometer in engineered seawalls.

Scope 3 Emissions: Indirect greenhouse gas emissions occurring across a company's value chain. NbS projects increasingly factor into Scope 3 accounting when organizations invest in watershed protection, sustainable forestry, or agricultural landscape restoration. The Science Based Targets initiative (SBTi) now provides guidance on incorporating high-quality NbS into corporate net-zero pathways.

Standards and Certification: Frameworks ensuring NbS projects deliver verified outcomes. The IUCN Global Standard for Nature-based Solutions provides a quality assurance framework, while emerging EU-level certification under the Nature Restoration Law will mandate third-party verification for projects receiving public funding.

What's Working and What Isn't

What's Working

Integrated urban water management combining grey and green infrastructure: Cities like Copenhagen and Rotterdam have demonstrated that hybrid systems—where constructed wetlands, bioswales, and permeable surfaces work alongside conventional drainage—outperform either approach alone. Copenhagen's Cloudburst Management Plan has reduced flood damage costs by 40% since 2012, with NbS components delivering €1.80 in benefits for every €1 invested. The key success factor is treating stormwater as a resource rather than a waste stream.

Corporate adoption of NbS for real estate climate-proofing: Leading European companies including Unilever, Nestlé, and Iberdrola have integrated NbS into facility management strategies. Unilever's manufacturing sites in the Netherlands have achieved 15% reductions in cooling energy through strategic tree planting and green roof installations, with payback periods averaging 6.2 years. Practitioners report that success depends on securing facility management buy-in early and embedding NbS maintenance into operational budgets.

Multi-stakeholder financing mechanisms: The EU's Natural Capital Financing Facility has catalyzed €300 million in NbS investments since 2019 by de-risking projects through blended finance structures. Projects that combine public grants (covering 20-40% of CAPEX), private equity, and revenue-generating ecosystem services consistently outperform those relying on single funding sources. The Landscape Finance Lab reports that projects with three or more funding partners achieve 73% higher survival rates over ten years.

Peatland restoration at scale: The Netherlands, Germany, and Ireland have launched ambitious peatland rewetting programs that deliver exceptional carbon returns. Restored peatlands sequester 2-5 tonnes of CO2 equivalent per hectare annually while eliminating emissions from degraded peat that can exceed 15 tonnes CO2e/ha/year. The German government's Peatland Protection Strategy targets 50,000 hectares of restoration by 2030, with verified carbon credits now trading at €45-80 per tonne.

What Isn't Working

Short project timelines misaligned with ecological reality: NbS interventions require 5-15 years to mature and deliver full ecosystem services. However, EU funding cycles typically span 3-5 years, creating pressure to demonstrate impact before systems have established. Practitioners consistently cite this mismatch as the primary cause of project abandonment. A 2024 assessment by the European Court of Auditors found that 28% of NbS projects funded under LIFE+ showed declining performance after initial funding ended.

Inadequate monitoring, reporting, and verification (MRV) systems: Many NbS projects lack baseline data, standardized indicators, and ongoing monitoring protocols. Without robust MRV, it becomes impossible to demonstrate additionality, justify continued investment, or learn from failures. The EU Nature Restoration Law will require member states to establish monitoring frameworks by 2026, but current capacity remains limited. Practitioners estimate that <15% of municipal NbS projects have adequate monitoring budgets.

Failure to account for maintenance costs in project planning: Establishment-phase CAPEX receives attention, but long-term operational expenditure (OPEX) is frequently underestimated by 40-60%. Urban trees require pruning, irrigation, and replacement; constructed wetlands need sediment removal and vegetation management. When maintenance budgets are cut during fiscal pressures, NbS assets deteriorate rapidly. The International Society of Arboriculture recommends budgeting €50-150 per tree annually for adequate urban forestry maintenance.

Greenwashing concerns undermining credibility: High-profile failures—including carbon offset projects that did not deliver promised sequestration—have created skepticism among investors and regulators. The voluntary carbon market's credibility crisis in 2023-2024 has spilled over into NbS more broadly, with institutional investors now demanding third-party verification for all nature-related claims. Projects without rigorous certification face increasing difficulty accessing capital.

Key Players

Established Leaders

European Investment Bank (EIB): The EU's climate bank has committed €1 billion annually to NbS through its Natural Capital Financing Facility and Climate Adaptation Platform. EIB provides technical assistance alongside financing, helping project developers meet rigorous due diligence requirements.

Arcadis: This Dutch-headquartered consultancy leads European NbS design and implementation, with over 200 completed projects across urban resilience, coastal protection, and watershed management. Their integrated approach combines engineering expertise with ecological restoration science.

IUCN (International Union for Conservation of Nature): The IUCN developed the Global Standard for NbS and provides technical guidance to governments, corporations, and project developers. Their European Regional Office coordinates policy advocacy and capacity building across member states.

Suez Environment: This French utility has pioneered NbS integration into water and waste management, deploying constructed wetlands, biofilters, and ecological corridors across municipal contracts. Their Lyon facility processes 300,000 m³ of wastewater daily using hybrid grey-green systems.

Rewilding Europe: This nonprofit organization has catalyzed landscape-scale restoration across 9 million hectares, developing innovative business models that generate revenue from ecotourism, sustainable forestry, and carbon credits.

Emerging Startups

Treeconomy (UK/EU): Develops digital MRV platforms for forest carbon projects, using satellite imagery and machine learning to verify sequestration claims. Recently raised €12 million Series A to expand across European markets.

Land Life Company (Netherlands): Deploys technology-enabled reforestation solutions, achieving 90%+ survival rates in degraded landscapes through precision planting and smart irrigation. Has restored over 5 million trees across Spain, the Netherlands, and Portugal.

Biome Makers (Spain): Provides soil microbiome analysis that optimizes NbS performance by matching intervention designs to site-specific biological conditions. Their platform serves agricultural and restoration applications across 50 countries.

Seawater Solutions (UK): Develops coastal restoration projects using saltmarsh and seagrass systems, creating revenue streams through carbon credits and aquaculture integration. Operating pilot sites in Scotland and Portugal.

Reforestum (Spain): Operates a corporate platform connecting businesses with verified reforestation projects, providing transparent impact tracking and carbon accounting integration. Partners include Santander and Telefónica.

Key Investors & Funders

European Commission (Horizon Europe): Provides €1.8 billion for NbS research and demonstration through the Biodiversity and Nature-based Solutions cluster, funding projects that advance scientific understanding and scalability.

Mirova Natural Capital: This Natixis subsidiary manages €1.5 billion in natural capital strategies, including the Land Degradation Neutrality Fund that finances sustainable land management across emerging and developed markets.

Finance for Biodiversity Foundation: Coordinates 150+ financial institutions with €18 trillion in assets committed to biodiversity-positive investment, including NbS allocation targets. Provides guidance on nature-related financial disclosures.

Climate Asset Management: A joint venture between HSBC and Pollination that manages natural capital investments exceeding €500 million, focusing on forest restoration, sustainable agriculture, and blue carbon projects.

Lombard Odier Investment Managers: Launched dedicated natural capital strategies with €300 million in committed capital, targeting NbS projects that deliver measurable environmental and financial returns.

Examples

1. Barcelona's Superblocks Program (Spain)

Barcelona's transformation of urban neighborhoods into pedestrian-priority "superilles" has become a global model for integrating NbS into urban planning. Since 2016, the city has implemented 21 superblocks, increasing green space by 300,000 m², planting 3,400 trees, and reducing vehicle traffic by 25%. Measured outcomes include 2.4°C reductions in peak summer temperatures within intervention zones, 12% decreases in respiratory illness hospitalizations, and 17% increases in property values. The program's €38 million investment has generated an estimated €150 million in health and economic co-benefits. Success factors include strong political leadership, extensive community engagement, and integration with public transit improvements.

2. Room for the River Program (Netherlands)

This €2.3 billion initiative has protected 4 million Dutch residents from flooding by reconnecting rivers with their floodplains rather than building higher dikes. Completed in 2019, the program lowered flood risk across 30 locations along the Rhine, Meuse, and IJssel rivers. The Nijmegen floodplain restoration alone created 250 hectares of new wetland habitat while reducing flood levels by 35 centimeters—sufficient to prevent €1.2 billion in potential damage during the 2021 European floods. The project demonstrates that NbS can outperform conventional infrastructure when designed at landscape scale. Monitoring indicates biodiversity has increased 40% across intervention sites.

3. Milan's ForestaMi Initiative (Italy)

Milan has committed to planting 3 million trees by 2030, representing the most ambitious urban forestry program in European history. Through 2024, the city had established 750,000 trees, reducing urban heat island intensity by 1.8°C in targeted neighborhoods and sequestering an estimated 45,000 tonnes of CO2 annually. The program integrates public lands, private properties, and peri-urban agricultural areas. Corporate partners including Gucci and Pirelli have contributed €25 million, while EU Green Deal funding provides an additional €40 million. The initiative's "Tree Registry" app enables citizens to track individual trees, fostering community stewardship and providing granular performance data.

Action Checklist

• Establish baseline measurements for all intervention sites before construction begins, including temperature profiles, biodiversity inventories, and hydrology assessments
• Design projects with 15-year time horizons minimum, securing maintenance funding commitments that extend beyond initial CAPEX periods
• Allocate 15-25% of total project budget to monitoring, reporting, and verification systems with standardized indicators aligned to IUCN Global Standard
• Engage local communities in design and governance from project inception, ensuring interventions address priority concerns and build social license
• Structure blended finance arrangements combining public grants, private investment, and revenue-generating ecosystem services to diversify risk
• Obtain third-party certification (IUCN, Verra, Gold Standard) to ensure credibility with investors and regulators
• Integrate NbS performance metrics into corporate Scope 3 reporting and CSRD disclosures where applicable
• Build adaptive management protocols that allow intervention adjustments based on monitoring data and changing climate conditions
• Document and share lessons learned—both successes and failures—to advance sector-wide knowledge and avoid repeated mistakes
• Connect with established networks (Finance for Biodiversity, NetworkNature) to access technical resources and peer learning opportunities

FAQ

Q: What KPIs should we prioritize when evaluating NbS project performance? A: Practitioners consistently emphasize three tiers of indicators. Primary KPIs include measurable ecosystem service delivery: temperature reduction (target >2°C within influence zone), carbon sequestration (2-10 tonnes CO2e/ha/year depending on intervention type), and flood risk reduction (expressed as reduced probability of defined return-period events). Secondary KPIs cover biodiversity outcomes, including species richness increases and habitat connectivity improvements. Tertiary KPIs address social co-benefits such as recreational access, community health improvements, and property value changes. The most successful projects track all three tiers and report against established baselines.

Q: How do benchmark ranges differ across NbS intervention types in European contexts? A: Urban forestry projects in temperate European climates should target 85-95% tree survival rates at year five, with mature canopy coverage of 30-40% at year fifteen. Green roof installations typically achieve 5-8°C surface temperature reductions compared to conventional roofing. Constructed wetlands for stormwater management should process 80-95% of design storm volumes, with pollutant removal rates of 70-90% for suspended solids and 40-70% for nitrogen. Coastal wetland restoration should demonstrate wave energy attenuation of 50-80% at maturity. Projects performing below these ranges warrant investigation of design, maintenance, or site selection issues.

Q: What distinguishes high-quality NbS projects from greenwashing? A: Credible projects demonstrate additionality (outcomes would not have occurred without the intervention), permanence (mechanisms ensure long-term protection), and third-party verification (independent assessment of claims). They maintain transparent baseline data, use conservative sequestration estimates, and disclose uncertainty ranges. They also address leakage risks (preventing displacement of harm to other locations) and prioritize local community benefits. Projects lacking these elements—particularly those making aggressive carbon claims without verification—should be viewed skeptically.

Q: How should organizations account for NbS investments under evolving EU sustainability regulations? A: Under CSRD and the EU Taxonomy, NbS investments may qualify as sustainable economic activities when they contribute substantially to climate adaptation or biodiversity objectives without significantly harming other environmental goals. Organizations should document how NbS interventions reduce physical climate risks to assets and operations, apply technical screening criteria for taxonomy alignment, and maintain records sufficient for limited assurance verification. The Taskforce on Nature-related Financial Disclosures (TNFD) framework provides additional guidance on nature-related risk assessment and opportunity identification.

Q: What are realistic payback periods for corporate NbS investments? A: Payback periods vary significantly by intervention type and how benefits are monetized. Green roofs with energy savings typically achieve payback in 8-15 years. Urban forestry investments around commercial properties see returns through property value appreciation and reduced cooling costs over 10-20 year horizons. Projects monetizing carbon credits can accelerate returns, with high-quality forestry credits now trading at €25-60/tonne in compliance markets. However, practitioners caution against over-optimizing for financial returns at the expense of ecological integrity—the most resilient projects prioritize genuine ecosystem restoration.

Sources

• European Environment Agency. (2024). "Nature-based Solutions in Europe: State and Outlook." EEA Report No. 18/2024.
• European Commission. (2024). "EU Biodiversity Strategy for 2030: Progress Report." COM(2024) 582 final.
• IUCN. (2023). "Global Standard for Nature-based Solutions: Implementation Guide." IUCN, Gland, Switzerland.
• Kabisch, N., et al. (2024). "Nature-based solutions for climate adaptation in European cities." Nature Climate Change, 14(3), 245-256.
• European Investment Bank. (2024). "Natural Capital Financing Facility: 2024 Annual Report." Luxembourg: EIB.
• European Court of Auditors. (2024). "Special Report 15/2024: EU funding for biodiversity and climate adaptation through nature-based solutions."
• Seddon, N., et al. (2024). "Getting the message right on nature-based solutions to climate change." Global Change Biology, 30(1), e16123.
• Task Force on Nature-related Financial Disclosures. (2024). "Recommendations of the TNFD: Final Report." TNFD Secretariat.