Nature’s Warren Buffett
Luke Leslie is building a global investment vehicle backing nature
Pension funds and institutional investors want to put serious capital into carbon markets. What they’ve lacked is somewhere credible to put it. The voluntary carbon market has long been plagued by low-quality credits, inconsistent standards, and projects that don’t deliver - making it effectively uninvestable for institutions that need their capital protected and their returns predictable.
Luke Leslie, co-founder and CEO of Key Carbon, solves that directly. He raises capital onto his own balance sheet and deploys it into businesses - generating high-integrity carbon credits; not as a broker, but as a co-owner. A Nairobi-based cookstove manufacturer distributing 7.5 million stoves across sub-Saharan Africa. 3.75 million mangrove trees planted on Myanmar’s coastline. €100 million committed to regenerative farming across nearly a million European hectares. Each investment is structured to institutional standards, with governance and verified credits that can withstand scrutiny.
The model comes from mining’s royalty and streaming structure, where you finance a project upfront and take a share of what it produces. Applied to carbon, it creates something the market has desperately needed: a permanent capital vehicle institutional investors can actually trust. That conviction ran through our latest conversation on The Impact Equation, and through our recent roundtable with Allister Furey of Sylvera, Shannon Smith of Chestnut Carbon, and Erica Vertefeuille of Terra Natural Capital.
A Financial Model, Not a Technology
Luke’s path to carbon finance winds through management consulting at Accenture, investment banking at UBS, and gold mining in East Africa. He has lived and worked in China, Hong Kong, outer Mongolia, Myanmar, and Mauritius. Each experience added a layer to his understanding of how capital moves through emerging markets and how to get things done in places where the rulebook hasn’t been written yet.
But it was in Mauritius, during COVID, that something became apparent. Swimming in seas where the coral reefs were dying, one of the early visible tipping points of climate change, Luke began to think about how to channel serious money into restoring natural carbon sinks. His insight was this: take a financial model that had worked brilliantly in mining and apply it to carbon.
In mining, a structure called the royalty and streaming model had been enormously successful. You provide upfront financing for a project and in return take a share of the underlying commodity it produces. Luke saw that the same logic could work for carbon: finance high-integrity projects upfront, then take a share of the future credits those projects generate. Key Carbon is not a fund with a fixed life and a mandate to return capital. It is a permanent capital vehicle — an investment company with its own balance sheet, raising money from pension funds, strategic investors like New York–listed Marex, private equity firms, and banks.
“Carbon project finance must be professionalised for net zero to happen,” Luke told us. It’s a line that could serve as a manifesto for his entire operation.
Why the Capital Markets Matter
To understand why this financial architecture matters so much, we need to understand the problem it solves. The voluntary carbon market, the part of the market where companies buy credits to offset emissions they can’t yet eliminate, had been funded in what Luke diplomatically described as a “haphazard” way. There are over two hundred different ways to generate a carbon credit. Capital was being deployed without rigour, without a clear way to compare one project to another, and the result was enormous capital destruction.
This echoed what we heard in our roundtable. Allister Furey, whose company Sylvera rates carbon projects using geospatial data and AI, described how he originally set out to be a project developer but got stuck at square one: there was no reliable way to tell whether a tonne of carbon was really a tonne. The market lacked the information to direct investment to the activities genuinely delivering climate benefits. That realisation pushed him to build Sylvera and the ratings infrastructure the market desperately needed.
Erica Vertefeuille of Terra Natural Capital framed the challenge through four lenses: scale, risk, return, and precedent. Two years ago, the voluntary carbon market was worth roughly two billion dollars. Today, the conversation has shifted to the forward market, where contracted future purchases have reached around seven billion dollars and the growth curve is steepening. But scale alone isn’t enough. You need structures that pension funds and banks recognise - structures with proper governance, risk-sharing, and contractual protections.
And that’s precisely what makes Key Carbon different. Luke isn’t brokering trades or acting as a middleman. He raises funds, deploys them into ventures he co-owns, appoints best-in-breed operators, and builds the governance frameworks that allow institutional money to enter a market it would otherwise consider too risky.
Three Bets on the Future
Key Carbon has built its portfolio around three flagship partnerships, each tackling a different dimension of the climate crisis - and each chosen with the same rigorous, bottom-up analysis that Luke brought from the mining world.
Burn Manufacturing and Clean Cooking - When Luke’s team assessed the two hundred-plus categories of carbon credit, clean cooking stood out. So called “clean cooking” replaces traditional open fires - typically three-stone fires burning wood - with highly efficient cookstoves that burn fuel with far less pollution. In many parts of sub-Saharan Africa, families cook indoors on open fires, exposing themselves to toxic smoke. Key Carbon analysed every clean cookstove manufacturer they could find and discovered that most stoves don’t last long. Burn, a Nairobi-based manufacturer with tens of millions invested in R&D, generates four times as many credits as the median producer. So the two companies created a fifty-fifty joint venture - Global Cook Stoves - with Key Carbon investing 47 million dollars. Burn manufactures the stoves at cost and distributes them across eight to ten African countries including Somalia, Nigeria, Kenya, and the DRC.
The numbers tell the story: 7.5 million people are now using those cookstoves. Key Carbon has found a strong correlation between cookstove distribution and school attendance, particularly for girls previously kept home to collect firewood. And the venture recently received the first-ever CCP-labelled clean cooking carbon credits under the Integrity Council’s framework — a stamp of quality that matters enormously as the market matures.
WorldView International Foundation and Blue Carbon - As Luke explained, mangroves can sequester many times more carbon per hectare than a mature tropical rainforest - but there’s a narrow belt around the world where you can grow them cost-effectively, and it tends to be in challenging places. Key Carbon chose Myanmar’s Bokepyin coastline because wet tropical conditions mean trees grow fast and costs stay low. Their partner is WorldView International Foundation, a non-profit founded in 1979 that has planted over 81 million mangroves globally with survival rates above ninety per cent. Together they’ve restored 1,500 hectares of degraded coastal wetland and planted 3.75 million trees, expected to sequester 2.3 million tonnes of CO2 over twenty-five years. WorldView has over 100,000 additional hectares under memorandums of understanding with governments worldwide.
InSoil and Regenerative Agriculture - The newest and potentially largest partnership is with InSoil, a Lithuanian climate finance company connecting European farmers with the financing to transition to regenerative practices. This year, Key Carbon and InSoil announced a landmark €100 million agreement - one of Europe’s biggest commitments to climate-resilient farming. The money flows as zero-interest green loans to small and medium-sized farms across Poland, Lithuania, and beyond, helping them shift from tilling to seeding and rebuild soil health. The target: one million hectares and the sequestration of over 35 million tonnes of CO2. As Luke described it, InSoil’s agronomists tell farmers: not only will you be more productive within a few years, but you’ll also qualify for carbon credits that add real value to your business.
A Co-Owner, Not a Broker
Most carbon market players operate as brokers - connecting buyers and sellers, or purchasing credits cheaply and selling them on. Key Carbon does neither. It raises permanent capital and co-owns the ventures it backs, appointing operators, insisting on minimum credit thresholds, and building in parent guarantees. Critically, it secures the right to repeat its initial investment on the same terms - if the carbon price doubles, Key Carbon keeps deploying at the original basis. In financial terms, they’re buying optionality, and options are most valuable when the underlying commodity is volatile, which carbon emphatically is.
The results are hard to argue with: according to Luke - a net asset value of around two hundred million dollars, a zero loss ratio, and returns that outperform top-quartile private equity. Erica Vertefeuille would recognise the playbook. She drew an analogy to early lithium financing: in 2015, no bank would touch a lithium project; today, they finance them routinely. The same normalisation is beginning with nature. Long-term offtake agreements with buyers like Microsoft and JP Morgan provide the capital protection institutional investors need.
Where the Market is Heading
Luke insists the entire business case must stand on financial fundamentals alone. Every investor in Key Carbon is looking for a financial return. The impact narrative is a bonus, not the basis. If Key Carbon can compete with private equity on a risk-adjusted basis, the taps open and serious capital flows into nature restoration at a scale that actually moves the needle.
During our conversation, Rafi landed on a phrase that stuck with all of us: Luke Leslie is building something that might best be described as an institutional investor in nature. It captures the ambition, the rigour, and the quiet audacity of what Key Carbon is trying to do. In a market still finding its feet, that combination of financial discipline and ecological purpose might be exactly what the planet needs.
*Listen to the full interview with Luke Leslie and our Carbon Markets Roundtable on The Impact Equation podcast, available wherever you get your podcasts.*
On Spotify here and Apple here
Until next time,
Adam and Rafi