SIRI Career Series: A Conversation with John Fennebresque on Nature Finance and Carbon Markets

This online event brought together students, researchers, and sustainability professionals for a candid discussion on the intersection of finance, forestry, carbon credits, and blended finance.

From Project Finance to Forests

John Fennebresque, a Columbia Business School alumnus (Class of 2000), began by tracing his career path—from early work in project and structured finance to founding his own advisory firm. While his background is firmly rooted in traditional finance and infrastructure, John explained how those same skills—structuring long‑term cash flows, managing capital stacks, and underwriting risk—translate directly to large‑scale natural assets such as forests.

What initially drew him into the space was not ecology, but finance. Over time, however, his work with remote sensing technologies, carbon registries, and forestry projects deepened his appreciation for ecological restoration and biodiversity as long‑duration, multi‑value assets.

The Greentrees Project: A Flagship Case Study

Much of the conversation focused on GreenTrees, the largest afforestation and reforestation (ARR) carbon projects in the United States, where John has served in several executive roles for ACRE Investment Management, the developer GreenTrees and other nature-based projects. Established over two decades ago through a collaboration involving landowners, nonprofits, the USDA, carbon registries, and the Clinton Climate Initiative, GreenTrees is widely regarded as a pioneering example of public–private partnership in nature finance.

Today, the GreenTrees project spans approximately 141,000 acres across Arkansas, Louisiana, and Mississippi, working with more than 570 landowners. It accounts for the vast majority of Afforestation, Reforestation, and Revegetation (ARR) credits issued in the U.S. voluntary carbon market and expects to cross the ten million tons of verified CO₂ sequestered later this year, with further growth expected as the forests mature.

Crucially, the project was designed to convert marginal agricultural land—often unprofitable yet heavily subsidized—back into ecologically valuable forestland. Carbon finance, paired with USDA conservation programs, provided the missing economic incentive to make reforestation viable for landowners.

Why Blended Finance Matters

A central theme of the discussion was blended finance. John emphasized that neither public funding nor private capital alone is sufficient to support large‑scale ecological restoration. Long biological timelines, delayed cash flows, and significant upfront costs make reforestation fundamentally different from conventional investments.

At GreenTrees, this challenge was addressed through a carefully structured blend of:

• Public support (e.g., USDA planting assistance),
• Private capital,
• Long‑term carbon credit revenues, and
• Revenue sharing with landowners.

This model, while complex, demonstrates that nature‑based projects can be financially viable over the long term—provided they are structured with institutional rigor.

Carbon Markets: Challenges and Opportunities

John offered a candid assessment of the voluntary carbon market, noting that recent years have been marked by volatility, changing standards, rating agency confusion, and fluctuating corporate demand. While these dynamics have created uncertainty, he remains cautiously optimistic.

Key challenges include:

• Inconsistent assumptions across carbon standards,
• Demand‑side hesitation linked to policy uncertainty and corporate net‑zero scrutiny,
• A shortage of professionals who understand both ecology and finance.

Yet, he stressed that high‑quality, verifiable nature‑based projects remain fundamentally supply‑constrained—and that demand is likely to recover as market confidence improves.

Technology, AI, and the Future of MRV

The conversation also explored the growing role of technology and AI in measurement, reporting, and verification (MRV). John discussed the development of advanced tools—such as remote sensing, LiDAR, digital twins, bioacoustics, and long‑term field data—to improve accuracy, reduce risk, and potentially lower the capital drag caused by conservative buffer requirements.

With over two decades of empirical forest growth data, John and his team are working toward platforms that could be scaled globally and shared with other project developers, enabling more transparent, data‑driven nature finance.

Advice for Students and Practitioners

The event closed with an active Q&A, touching on carbon pricing, forward contracts versus spot markets, biodiversity credits, and career pathways into the space. One of the most resonant messages for students was clear:

You don’t need to start your career in “nature finance” to end up there—but strong fundamentals in finance, data, and systems thinking are invaluable. What nature finance needs are experts who are fluent in both finance and ecology—and who can effectively bridge these two fields. As nature finance continues to evolve, the session underscored both the complexity and opportunity of the field—and the critical role that the next generation of professionals will play in scaling credible, high‑impact solutions.