According to a 2021 OECD report, two-thirds of African cities are at “extreme” risk of climate and water-related shocks. Violent climate events, heat waves and droughts are thus at the top of the risks incurred by urban areas. Rapid urbanization, unsustainable development and degradation of natural ecosystems exacerbate these risks. 

Nature-based solutions (NBS), which rely on natural ecosystems and the services they provide to human activities, address these urban challenges, while simultaneously providing benefits in terms of human well-being and biodiversity. However, they are still little integrated into urban planning processes and decision support tools available to planners. The lack of knowledge, data and experimentation on nature-based solutions therefore hampers their adoption and deployment. 

The objective of this research project is to enable, through the construction of a strategic framework, the deployment and scaling of nature-based solutions, in particular to address water and heat risks. The challenge is to improve the ecological resilience of cities by helping them identify the risks they must prepare for, to assess the potential of NBS to address them and to develop implementation and funding strategies for these NBS as part of the urban planning process. 

A fast, effective and practical methodology for assessing the potential of nature-based solutions will be made available to the cities of Addis Ababa and Kigali, which are the two pilot cities of this research project. The project is led by WRI, in partnership with the Addis Ababa Urban Development Department, the Ethiopian Institute of Architecture and the Rwanda Young Water Professionals Association. This methodology is intended to be adopted by other urban centers to allow a broader appropriation and mobilization of NBS in cities. 

At the methodological level, the construction of a strategic framework for nature-based solutions is interesting for two reasons:

• Identification of flood risks, heat islands, water supply and biodiversity potential of cities through the production of composite maps and the mobilization of satellite data;
• Participatory construction of the strategic framework through workshops with stakeholders of both cities to validate the priority areas of intervention and identify the NBS most adapted to the issues of each area.  

Developed by the WRI research team with the cities of Addis Ababa and Kigali, the Strategic NbS Framework can support cities in selecting and implementing appropriate nature-based solutions (NbS). 

By integrating globally available data sets with local data, it helps identify areas of a given city that are susceptible to extreme flooding and heat, as well as opportunities to expand urban green spaces and create ecological corridors. 

To ensure successful implementation, collaboration between public authorities, technical experts, and community leaders is essential. Using this framework, citywide maps can be quickly generated to identify priority areas. After a validation by city stakeholders, field experts then play a key role in designing effective NbS, tailored to local conditions. 

Although it has limitations in data detail, the Framework provides a solid starting point to build sustainable cities. Additional guidelines provide technical information on usable NbS, as well as case studies. These guidelines are available for download below: 

Download the guidelines

A webinar from the Research Conversations series was held to present the project's findings, and these research findings are summarized in a policy brief available for download below.

The research project identified a series of lessons to facilitate the deployment of nature-based solutions (NbS), taking into account the specific needs of cities. These lessons highlight the potential of nature in urban resilience planning and climate action:

• To increase awareness and institutional integration:

1. Set up multi-stakeholder processes to support dialogue and the prioritization of identified NbS.
2. Rely on case studies to facilitate understanding and engagement.

• To enhance data availability for more effective planning:

1. Combine local and global datasets to carry out multi-hazard assessments (flooding, urban heat islands, etc.).
2. Encourage citizen science initiatives for data collection, and ensure it is considered in decision-making.

• To strengthen planning and implementation linkages:

1. Establish dedicated governance structures (such as a mayoral committee) to coordinate various technical services involved and mobilize funding.
2. Develop common reference frameworks (design standards, guidelines, etc.) to strengthen political and public support.

• To secure long-term financing:

1. Integrate NbS into existing city investment programs.
2. Include strategies for public-private partnerships and use a multi-benefit assessment framework to demonstrate their long-term value.

• To adapt solutions to the local context and ensure monitoring:

1. Launch NbS pilot projects with monitoring systems to track their performance.
2. Integrate gender, equity, and inclusion considerations from the selection phase of each NbS.

Public actors need to monitor the state of the environment in order to assess the effectiveness of their actions, prioritize management policies and measures, and thus objectively establish their contribution to the conservation of natural capital. To do so, they must be able to rely on science-based standards to identify the thresholds at which environmental functions can be considered sustainable.

The ESGAP (Environmental Sustainability Gap) is an innovative tool for assessing the condition of a territory’s environmental functions and how sustainable they are. For all critical components of natural capital in the territory concerned (air or water quality, pollution, forest resources, fisheries, etc.), this indicator calculates the difference between their current state and a state that would be sustainable (i.e., a state compatible with the sustainable functioning of the processes necessary for the preservation of life, human activities and well-being). This allows for the calculation of the “environmental sustainability gap”, which highlights the path to environmental sustainability. This can then serve as a guide for public policies to estimate and preserve the critical functions of the natural capital of a given territory. ESGAP has already been tested in New Caledonia, Kenya and Vietnam.

Within the framework of the ECOPRONAT research programme, AFD aims to develop methodologies for assessing strong sustainability, that is, adopting demanding criteria concerning the non-substituability of natural capital by other forms of capital (physical among others) in a territory or country. AFD also wants to promote their use in international frameworks and contribute to emerging international standards on the good ecological state of ecosystems.

Find out more about ECOPRONAT

Building on the previous work of University College London (UCL) on the application of ESGAP in countries of the Global South, this research project led by UCL aims to implement the ESGAP framework in Colombia and South Africa. It will test its relevance in fostering public policy dialogue in these two countries that already have a regulatory framework and natural resources management, but where not all data on biodiversity is available. 

More specifically, this project has four objectives: 

1. Developing the ESGAP components related to biodiversity and the state of ecosystems that could be used by Colombian and South African governments, and promoting the use of science-based targets for ecosystem maintenance;
2. Promoting reflection on strong sustainability in Colombia and South Africa through the ESGAP framework, by assessing whether the activities carried out in these countries are within the safe operating space for humanity;
3. Clarifying how the ESGAP framework aligns, complements and adds value to other types of existing sustainability indicators that national governments are already using;
4. Strengthening the capacity of partner countries to implement the ESGAP framework beyond this research project. 

The ESGAP framework is based on a dashboard that provides information on changes in the functional state of 23 components of the environment, focusing on the gaps that exist between these changes and the objectives of maintaining or achieving a "good environmental state". These components cover the 4 main categories of critical and essential environmental functions: resource provision, pollution reprocessing, biodiversity and human health. The scores for each of the twenty-three components are then aggregated to form a synthetic indicator and a dynamic indicator.

The research activities in the two pilot countries is carried out by researchers from Stellenbosch University (South Africa) and the National University of Colombia (UNAL). Capacity building will include training four postgraduate students as well as awareness-raising activities targeting policymakers and other stakeholders, in order for them to take ownership of the ESGAP and use it during public policy formulation.

The research teams will produce scientific papers on the relationship between the ESGAP framework and other sustainability indicator initiatives, as well as on the work and calculations of the ESGAP indicators carried out in each country, comparing the cases of Colombia and South Africa. A specific report will be produced on indicators of the state of biodiversity and ecosystems as well as the identification of data sources for the two countries studied.

In addition, an international workshop will be organized to present the complementarities between the ESGAP framework and relevant initiatives of existing sustainability indicators.

Finally, the research team intends to produce several documents for decision-makers and public policy actors:

• A summary of the review of biodiversity indicators and the state of ecosystems, which may be useful for negotiations at the Conferences of the Parties (COPs) to the Convention on Biological Diversity and for the design of national biodiversity strategies and action plans (NBSAPs);
• A webinar with a webinar report on the relationship between the ESGAP framework and other international sustainability reporting initiatives;
• A summary for decision-makers in each partner country on the rationale of the strong sustainability development approach and the methodology and ESGAP indicators that enable it to be implemented.

Download the publications related to the project: 

• The SDGs Provide Limited Evidence That Environmental Policies Are Delivering Multiple Ecological and Social Benefits, Earth's Future vol.12 (May 2024)
• Enhancing Environmental Sustainability Through the Environmental Sustainability Gap (ESGAP) Framework in Colombia, Policy Dialogues n°67, Editions Agence française de développement (October 2024)
• Strong sustainability in the SEEA and the wider indicator landscape, One Ecosystem (May 2025)
• Assessing environmental sustainability in Colombia: Metrics and policy recommendations, Environmental and Sustainability Indicators n°27 (September 2025)

A "Research Conversations" webinar presented the results of the articles to the scientific community in November 2024: