Abstract

Natural climate solutions (NCS) offer significant mitigation potential, yet adoption is constrained by limited understanding of implementation barriers. Analysing 15,572 constraint observations from 501 studies and projects across 137 countries, the study identifies social-behavioural, knowledge, and government or organisational barriers as most prevalent, with weak policy coordination the most frequent constraint.

Introduction

NCS—land and water management actions that reduce emissions or enhance carbon sequestration—are cost-effective mitigation options with substantial potential. However, implementation remains limited due to diverse constraints across local to national scales. Existing analyses often overlook these constraints, creating a gap between technical and feasible mitigation potential. This study addresses that gap through spatially detailed, pathway-specific analysis.

Results

The dataset combines 347 studies and 154 projects, covering 20 UN subregions. Reforestation, agroforestry, and avoided forest conversion dominate pathways. A total of 15,572 constraint observations reveal no single dominant barrier category, though social-behavioural (19%), knowledge (17%), and government or organisational (16%) constraints are most frequent.

The most common individual constraint is lack of policy coordination or implementation capacity, followed by weak enforcement of environmental laws. Other key barriers include insufficient design information, scepticism towards NCS, and limited funding access. Projects typically face multiple constraints, averaging 7.8 per case across 3.2 categories, indicating systemic complexity.

Constraint patterns are broadly consistent across pathways and regions, though rankings vary. Social-behavioural and knowledge constraints dominate most pathways, while finance is particularly significant in African subregions. Regional differences highlight the need for context-specific interventions.

Discussion

NCS implementation is hindered by diverse and interrelated constraints requiring integrated solutions. While financing is important, non-financial barriers—such as lack of information, social trust, and institutional capacity—are more prevalent. Addressing these requires coordinated actions, including strengthening governance, improving knowledge dissemination, and fostering stakeholder engagement.

The study emphasises targeting “ultimate” constraints that drive others, improving intervention efficiency. Key enabling actions include empowering local communities, enhancing technical capacity, improving policy coherence, and developing markets and financing mechanisms. These interventions also deliver broader socio-economic benefits beyond climate mitigation.

Limitations include uneven geographic and pathway coverage and reliance on researcher and project-reported data, which may not fully capture local perspectives. Constraint frequency does not necessarily reflect importance, and further context-specific analysis is required to assess feasibility and prioritise interventions.

Methods

The study combines a systematic literature review with a global survey of NCS projects conducted between 2022 and 2023. It identifies 46 discrete constraints grouped into eight categories, including finance, markets, knowledge, and social-behavioural factors. Data are geo-referenced to administrative levels and analysed by pathway and subregion.