Integration for greater impact

Nature-based solutions

This section summarizes key findings from the recent IEO evaluation on NbS (GEF IEO forthcoming-i), an area of work that spans multiple focal areas and exemplifies integrated approaches. NbS offer the potential to address biodiversity conservation, climate change adaptation and mitigation, water security, and land degradation, while also delivering broader societal benefits through the sustainable management of ecosystems.

Portfolio and evolution since GEF-5

In the absence of a formal classification system, the NbS portfolio was identified through a tailored three-layered screening and scoring process. This method applied internationally recognized criteria and led to the identification of 933 NbS-aligned projects between GEF-5 and GEF-8. The portfolio includes projects funded through the GEF Trust Fund, the LDCF, the SCCF, the GBFF, or a combination of these funding sources.

Main areas of intervention

The GEF NbS project portfolio encompasses a wide range of approaches, often employing a diverse mix of interventions. Projects commonly combine multiple NbS approaches to tackle issues such as biodiversity loss, climate change, land degradation, and community resilience in a holistic and scalable manner. The most common are ecosystem-based management strategies, including integrated watershed, forest, coastal zone, and landscape management, which typically merge area-based conservation with active restoration efforts such as reforestation and soil rehabilitation. Projects also promote agriculture-centered NbS (such as climate-smart agriculture, agroforestry, and conservation agriculture), ecosystem-based approaches to climate and disaster risk reduction, and nature-infrastructure hybrids (such as green or blue infrastructure and mixed green-gray systems) aimed at enhancing resilience and supporting biodiversity and local livelihoods.

Relevance

The GEF’s NbS portfolio is well aligned with its core mandate and multilateral environmental agreements but remains underused within the overall project pipeline. Drawing on a diverse set of interventions, from capacity building and policy reform to ecosystem restoration and green infrastructure, these projects contribute to multiple multilateral environmental agreements targets and help address complex environmental and development challenges. Despite this strategic fit, NbS initiatives make up only about 30 percent of the total GEF portfolio. The lack of a clear operational definition and systematic tagging constrains strategic coherence and comprehensive relevance assessments.

Despite strong alignment with GEF and national priorities, questions persist regarding the cost-effectiveness of NbS. The relevance of NbS within the GEF stems from their ability to foster integrated approaches that create synergies. NbS also offer ways to balance environmental and social benefits, ensuring fair distribution among stakeholders and across different levels of implementation. However, it is not clear whether certain NbS projects can deliver outcomes more cost effectively than alternatives. The current portfolio contains too few systematic cost-benefit assessments, leaving the economic case underdeveloped and constraining investment decisions by both GEF and private sector stakeholders, who typically favor interventions with shorter payback periods. The lack of rigorous cost-effectiveness studies undermines informed resource allocation and constrains the broader adoption and scaling of NbS within the GEF portfolio.

Performance and effectiveness

The GEF’s NbS-aligned projects perform comparably to the broader portfolio in delivering planned environmental outputs but lower in terms of sustainability. Approximately 80 percent of NbS projects achieved or surpassed key targets, such as improved land management, habitat restoration, and species protection, compared to 78 percent across all GEF-funded projects. However, only 62 percent of NbS initiatives were rated “likely” or “highly likely” to sustain outcomes, in contrast to 68 percent of non-NbS projects. Persistent issues were limited follow-on funding, weak integration of adaptive management practices, and insufficiently embedded local governance systems. Projects with strong stakeholder co-management and clear financing strategies tended to perform better, highlighting the value of inclusive governance and aligned policies in securing long-term NbS impacts.

GEF projects that incorporate NbS deliver important socioeconomic co-benefits that help sustain global environmental benefits. However, their effectiveness is difficult to systematically demonstrate due to measurement challenges, limited adaptive management, and fragmented learning across the portfolio. NbS-aligned projects generate benefits such as improved livelihoods, higher farm incomes, greater resilience, and employment opportunities—all critical for sustaining global environmental benefits. However, demonstrating these results is limited by the uneven inclusion of socioeconomic indicators in project designs, the absence of robust baseline data, and the limited scope of the GEF’s official co-benefit metric (Core Indicator 11). Moreover, learning across the NbS portfolio remains fragmented and largely reactive, due to the lack of dedicated guidance, a shared theory of change within the GEF, and effective mechanisms for integrating evidence-based Indigenous and local knowledge with scientific expertise. These gaps limit the potential for systematic learning, adaptive management, and the realization of transformational impact through NbS.

The engagement of diverse stakeholders in NbS projects has increased under recent GEF policy reforms and the GBFF’s 20 percent funding allocation for IPLCs. Inclusion is central to NbS effectiveness, and GEF-funded projects, particularly more recent ones, show increased effort in engaging marginalized groups. The GEF’s Policy on Gender Equality (2017) and accompanying guidance (2018) have supported gender-responsive project design and planning. Despite this progress, projects continue to face difficulties in managing inherently complex stakeholder dynamics, integrating gender considerations meaningfully, ensuring substantive IPLC participation throughout the project cycle, and navigating sensitivities around traditional knowledge.

Policy and institutional coherence is key for NbS effectiveness. Projects that actively align with national and local policy frameworks, foster cross-sector coordination, and respond to shifting policy landscapes tend to secure stronger government ownership and achieve better outcomes. Conversely, gaps in policy alignment, overlapping mandates, legal inconsistencies, and political or administrative instability often weaken coherence, especially in low-capacity settings where environmental institutions have limited sway over broader development agendas. Addressing these challenges requires bridging domestic institutional and sectoral gaps while also aligning international funding mechanisms and conventions to better support national priorities and enable effective, impactful deployment of NbS.

GEF interventions in innovative finance have shown opportunities, though replicability and long-term viability remain difficult to achieve. Pilot initiatives in blended finance, environmental bonds, and nature-focused impact investing have secured higher levels of cofinancing, yet scaling these models across the portfolio remains limited. Common barriers include challenges in building durable private sector partnerships, reconciling conservation goals with financial return timelines, and ensuring the sustainability of funding. While early results from pilots are encouraging, they have not yet established a consistent path to economic sustainability for NbS. The mismatch between investors’ expectations for short-term returns and the longer-term benefits of NbS continues to hinder broader capital mobilization and sustained engagement.

The overall effectiveness of the GEF’s NbS interventions is often limited by knowledge and capacity gaps among stakeholders, which impede the consistent delivery of robust, resilient, and context-appropriate solutions. Implementing successful NbS projects is frequently challenged by a lack of technical skills and local capacity. Despite the strong interest in NbS, turning this interest into well-designed, site-specific interventions requires solid evidence and understanding. These gaps can result in implementation risks, uncertainty about long-term outcomes, underestimated resource needs, and missed opportunities to incorporate the valuable traditional knowledge of IPLCs. While the GEF’s Principles and Guidelines for Engagement with Indigenous Peoples and the Guidelines on GEF’s Policy on Social and Environmental Safeguards aim to integrate traditional knowledge, evaluations have highlighted that Western approaches dominate, limiting the integration of diverse knowledge systems.

Sustainability

The GEF partnership has supported promising cases of policy change through NbS, yet broader systemic shifts are limited by capacity and financing gaps. Several projects have helped incorporate NbS into national policies, testing innovative solutions, and attracting blended finance. However, many still face difficulties in achieving lasting and widespread impact. Ongoing challenges include insufficient technical and managerial expertise among implementing entities, a lack of clear scaling strategies, and uncertainty about sustained financial support. Where successful scaling has occurred, it has been supported by adaptive implementation, inclusive multistakeholder engagement, and clear financing mechanisms (box 5.8). Conversely, where adoption has faltered, weak economic viability and institutional silos remain key barriers.