World Resources Institute: “We’re seeing NBS projects in Sub-Saharan Africa gaining traction and being put from concept into implementation”

Exclusive interview with Lizzie Marsters, Senior Manager Environmental Finance, Natural Infrastructure & Cities4Forest Initiatives, World Resources Institute

Q: Thank you for joining us. Tell us a bit about your background and your current role at the WRI.

Hi, thank you so much for having me. I’m Lizzie Marsters, the Senior Environmental Finance Manager for the Cities4Forests and Natural Infrastructure Initiative at the World Resources Institute. My role focuses on bringing finance in as a tool to catalyze greater restoration and protection of nature. I’m really passionate about valuing nature for its holistic contributions to communities and ecosystems—how we account for its disaster risk protection benefits, support for community cohesion, and ecosystem services. My job is to help mobilize funding and finance as one of the key tools to drive greater restoration and protection efforts.

One of my favorite aspects of the job is working with communities, utilities, governments, nonprofits, and other stakeholders to evaluate and tailor local solutions that strengthen their disaster risk resilience. I work both in the U.S. and in Africa. In the U.S., where the financial enabling environment is often more developed, we work to pilot and test innovative approaches. For example, in Utah—where there’s high catastrophic wildfire risk—we launched a Resilience Fund in partnership with national and local governments and water utilities. Together, we pooled $8.3 million to reduce wildfire risk and protect the watersheds that supply water to communities, agriculture, and the downstream Great Salt Lake. This includes treating over 15,000 acres in the watershed to protect a total of 60,000 acres.

In Africa, I work on the Green-Gray Infrastructure Accelerator, which we’ll talk more about. In essence, it’s a facility that helps cities move along the arc of project development for nature-based solutions—getting them investment-ready and enabling them to deliver climate resilience at scale.

I’ve been with WRI for five years. Prior to that, I worked at a nonprofit focused on creating demand for carbon-smart wood. We partnered with industries that buy and build with wood to encourage purchases of wood grown on longer rotations using improved management practices—aiming to store more carbon in the process. Before that, I was in the private sector as a portfolio manager in investor relations for a timberland investment management organization (TIMO), where I worked on business strategy for large-scale timberlands in Latin America.

 

Q: You were part of a report on the potential of nature-based solutions for climate resilience in Sub-Saharan Africa that surveyed nearly 300 projects. What were the main take-aways.
Yes, this report has truly been a labor of love over the past three years. It’s called Growing Resilience, Unlocking the Potential of Nature-Based Solutions for Climate Resilience in Sub-Saharan Africa. It was a collaboration between WRI and the World Bank, with contributions from the African Development Bank.

Through this study, we examined the status and trends of nature-based solution (NBS) projects that were specifically designed to address climate resilience in Sub-Saharan Africa between 2012 and 2023. We identified nearly 300 projects in total. Some were solely nature-based or green projects using nature to deliver climate resilience benefits. For example, a common concern in the region is landslides and erosion on steep hillsides following heavy rain. An NBS intervention would be to revegetate those slopes to prevent sediment from harming downstream communities.

Of the projects we found, some were purely green infrastructure, and others were green-gray—blending natural systems with traditional infrastructure. Together, these projects secured over $21 billion in funding, of which $12.5 billion went specifically toward the nature-based components. We also found a 15% average annual increase in the number of NBS projects from 2012 to 2021, along with a 23% average annual increase in new funding. That’s a significant signal that nature-based solutions are gaining traction and moving from concept to implementation in the region.

The scope of these projects also reflected a growing understanding—especially among national and local governments—that NBS can address multiple climate-related challenges. Most projects were designed to deliver a mix of outcomes, with improving water quality, expanding water supply, and mitigating flood risks among the top three goals. At the same time, they provided critical co-benefits like job creation, biodiversity enhancement, and food security. So these projects are truly win-win solutions—strengthening climate resilience while delivering important social and economic outcomes.

However, the report also revealed some gaps. These interventions aren’t being applied evenly across landscapes. More than 70% of the projects were located in rural areas—primarily upper watersheds or areas outside of cities. In contrast, only 16% were located in or around urban areas. Given the broad benefits of NBS, it’s clear we need to increase the pace and scale of investment in urban NBS opportunities—including green, gray, and hybrid solutions. With Africa’s future increasingly urban, scaling up urban NBS infrastructure is critical.

Let me share one example of what this looks like in practice. One key finding from our research was the need for more demonstration projects—examples that show the climate resilience benefits, economic outcomes, and how people are positively impacted. One standout project is led by the Guma Valley Water Company in Sierra Leone. What makes this unique is that it’s a utility—an actual infrastructure operator—leading, managing, and executing the NBS project. This is the kind of leadership we need to see more of in the region, because utilities and infrastructure operators are often the ones with the greatest financial incentives to invest in NBS.

Most of the projects we found—over 60%—were led by national governments. Less than 1% were run by infrastructure operators, which shows the potential for growth in this space.

This particular project, funded by the African Development Bank, is part of the Freetown WASH and Aquatic Environment Revamping Project. It addresses water security by combining upstream watershed restoration and reforestation (green infrastructure) with traditional gray infrastructure like new water tanks. It’s expected to provide clean water access for an estimated 1.4 million people and improve sanitation for at least 200,000 residents in vulnerable communities. It also builds local capacity—training nearly 500 people in plumbing and business management—and is expected to create more than 2,700 new jobs in the region.

This is just one of many exciting projects we documented. We’re encouraged by what we found and hopeful we’ll see even more of these kinds of investments across the continent.

Image source: © John Cole

 

Q: How does the Green-Gray Infrastructure Accelerator work, and which African cities are involved?
In the report, one of the key gaps we identified was the lack of urban green infrastructure projects. So, taking our research into action, we felt it was essential to focus our resources and technical expertise on urban areas. Cities in Sub-Saharan Africa are experiencing rapid population growth, often resulting in unplanned development, loss of biodiversity, and diminished green space. At the same time, urban communities are among the most vulnerable to climate change impacts—they are on the front lines of flood and heat risk.

The question became: How can we design solutions tailored to meet the needs of African cities, while ensuring that communities have stronger climate resilience and more equitable access to resources?

To that end, we created the Green-Gray Infrastructure Accelerator. It’s a program that provides resources, innovative approaches, and strategic engagement with communities, governments, and investors to remove the barriers to designing and implementing gender- and socially-responsive hazard mitigation solutions and green-gray infrastructure.

The Accelerator works with an initial cohort of 11 cities across seven countries. In these cities, local WRI staff are embedded to support governments in establishing the policy frameworks needed to make it easier to design, fund, and finance nature-based solution projects.

We’re also working with cities to develop strong business cases—helping them advocate for domestic resources and unlock international and investor financing. This includes preparing cost-benefit analyses, identifying appropriate financial mechanisms, and making projects investment-ready.

Equally important is community engagement and capacity building. We’re focused on ensuring that these projects are designed with meaningful community and stakeholder input so that their benefits reach the most vulnerable populations and result in real, tangible climate resilience.

This program fosters peer-to-peer learning and provides targeted project development assistance. In addition, we are convening investor roundtables to help bridge the gap between city governments and funders—ensuring projects are eligible for the types of capital available and are structured to deliver their intended social, environmental, and economic outcomes.

 

Q: This is a very nascent sector, and you are the coalface of a lot of groundbreaking initiatives, what have been the main challenges so far? And what has been the most exhilarating or surprising?
This is a very nascent sector, and it’s an exciting place to work. Some of the key challenges we’ve seen so far relate to gaps in policy and social inclusion practices.

One of the key questions is: how do we create an enabling environment that puts nature-based solutions on par with traditional gray infrastructure? Often, when cities evaluate options to deliver infrastructure or address disaster risks, gray infrastructure is the default. We want to encourage policies and practices that elevate nature-based solutions to equal standing—demonstrating their benefits and making them a viable alternative.

Another challenge is the lack of projects that clearly showcase success. We don’t always have the monitoring and evaluation data to quantify the impact—how much resilience was delivered, how much flood risk was reduced, or how much urban heat was avoided thanks to nature-based interventions.

So part of the work ahead is twofold: we need to create bankable projects and invest in robust monitoring and evaluation for the more than 300 NBS projects across the region. This will help prove that these projects deliver real benefits—not only in terms of climate resilience but also in economic savings, job security, and broader social outcomes.

Another major challenge is the limited availability of repayment sources for NBS. For gray infrastructure, funding typically comes from established sources—like ratepayers or city budgets—that provide predictable cash flows. In contrast, NBS projects often depend on less immediate or less predictable revenue sources. For example, cash flows from timber or fruit harvests might be years away, and investors are less likely to take on that kind of risk without a proven track record.

This is why one of our priorities is to improve understanding of the financial viability of NBS—and build investor confidence in these models.

A further barrier is the mismatch between the size of NBS projects and investor expectations. Institutional investors often look for deal sizes of $25 million or more, while many NBS projects are much smaller—often under $5 million. One promising solution is bundling green infrastructure with gray infrastructure into a single package. This creates the scale that investors are looking for and pairs NBS with familiar, more secure repayment structures, which makes the overall investment more attractive.

What’s encouraging is that many of these challenges are starting to be addressed through new research and project implementation. WRI recently published a global review of over 312 nature-based solution projects. It found that for every $1 invested in adaptation, $10 in benefits are generated over a 10-year period. The study also showed that projects in sectors like agriculture, water, health, and infrastructure delivered average returns of 27% annually—with some health-related projects yielding returns over 75%.

This reinforces what we call the triple dividend of NBS: economic benefits from cost savings, social benefits from improved equity and livelihoods, and environmental benefits through stronger ecosystem services and public health outcomes.

It’s exciting to see the evidence base growing and aligning with the projects on the ground. I’m really optimistic about the potential for this region to expand its investment in nature-based solutions.

 

Q: You were involved in issuing the world’s first certified green bond to acquire forests for water quality. What is your vision for what carbon markets can mean for the continent?
This is a really interesting project. In the U.S., we supported a water utility—Central Arkansas Water—in issuing the world’s first certified green bond specifically to protect forests for water quality. It was a classic green-gray infrastructure project, combining forest management and forest acquisition (the green components) with infrastructure efficiency upgrades, such as new pipes and pumps (the gray components).

The bond totaled $31.5 million, and what made it especially important was the way it was structured for repayment. As I mentioned earlier, one of the major challenges with nature-based solutions is identifying reliable repayment streams. In this case, the gray infrastructure components were repaid through traditional ratepayer fees collected by the utility for its services.

The green components—about $10 million of the bond—had two secured sources of repayment and a potential third. First, Central Arkansas Water established a dedicated watershed protection fee. It’s a modest fee—just a dollar or so per bill—but it generates about $2 million annually, which the utility can use to secure financing for large-scale forest acquisition projects. This dedicated funding stream gave them the ability to bond against it.

Second, they’re conducting selective timber harvesting—transitioning lands from plantation forests to native species forests that offer better water protection benefits. Finally, they’re exploring carbon credits as a third potential revenue stream.

One aspect I really appreciate about Central Arkansas Water is how responsibly they’re approaching carbon. They’ve committed to net-zero targets and are actively working to reduce their hardest-to-abate emissions—through energy efficiency, fleet electrification, and operational changes. They will only rely on forest carbon offsets when they’ve exhausted all other mitigation pathways.

This is especially important when thinking about applying similar models in Sub-Saharan Africa. The integrity of carbon markets depends not just on the suppliers of the credits, but on the buyers as well. If the buyer is using carbon credits to avoid meaningful emissions reductions, then the environmental integrity of the system breaks down.

We strongly recommend a thorough evaluation of both the supply and demand sides of the carbon credit market. On the demand side, buyers should be required to demonstrate robust efforts to reduce emissions across their operations. On the supply side, the credits must be rooted in truly additional, high-integrity nature-based practices.

Improving integrity across the board—ensuring that carbon credits represent real, additional climate benefits—is essential. We’re excited to see Central Arkansas Water leading by example and hope to see similar innovations, with strong environmental safeguards, take root in other regions as well.