(Bloomberg) -- South Pole, the world’s top seller of carbon offsets, said its chief executive is stepping down following months of allegations that the company overstated the climate impact of products that it sold.

Renat Heuberger, the CEO and co-founder of South Pole, will step down with immediate effect, the Zurich-based company said in a statement on Friday. He will be replaced by John Davis, commercial director, Asia Pacific, who becomes interim CEO until a permanent successor is found, it said.

The news comes just a fortnight after South Pole said it had terminated its contract with Carbon Green Investments, which owns and develops a mega carbon-offset project in Zimbabwe, known as Kariba. South Pole was the carbon asset developer for the project, which became its biggest moneymaker.

The Kariba project has been the subject of regular scrutiny amid repeated allegations of greenwashing from climate activists. South Pole opted to sever ties with the Kariba project’s developer in October, following “careful consideration of the project, issues involved and allegations that have been raised publicly,” it said at the time.

In its statement on Friday, South Pole said it’s “determined to learn from the experience” of Kariba.

At the “core of this commitment is a focus on enhancing its group-wide quality and risk controls, and due diligence processes,” it said.

The board of South Pole said it “believes this exercise will be best delivered by new senior leadership, with the required experience to design and implement a comprehensive program of review, change and governance and process improvements, while also improving stakeholder engagement, trust and communication.”

Heuberger, 46, will remain at South Pole in a non-executive and advisory role “to support the interim and incoming leadership,” according to Friday’s statement. Christoph Grobbel, another founding partner of the company, will step back from his executive roles “to fully focus as a non-executive chairman on supporting the company through the transition.”

Heuberger started South Pole with a group of college friends from Zurich’s ETH university. They rode an initial wave of euphoria for carbon trading after the ratification of Kyoto Protocol in the mid-2000s, which established a global market for carbon. A decade later, they responded to the collapse that hit carbon prices by branching out into climate consulting services.

At its peak, South Pole’s valuation topped $1 billion, making it one of the world’s first carbon unicorns.

Davis, the newly appointed interim CEO, said South Pole “recognizes its responsibility not only to meet industry standards but also to lead in the development of world-class risk and quality assurance systems, particularly within the emerging carbon market.”

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