Microsoft has signed a carbon removal deal with Brazilian enhanced rock weathering (ERW) firm InPlanet for more than 28,500 tons of carbon credits.

The carbon removals are expected to be delivered between 2026 and 2028. The removals will be generated through InPlanet’s ERW program in Brazil, which is the largest in the country, spanning more than 12,000 hectares of farmland.

According to the company, the deal will support further scientific research into the process to further validate the process under real-world conditions.

ERW works by speeding up the natural process of carbon removal when rainwater interacts with silicate rocks. This is done by crushing tons of silicate rock into a powder and spreading it on farmland to accelerate rock dissolution. Subsequently, when it rains, the rocks react, generating alkalinity, which pulls CO2 out of the atmosphere and into water as a bicarbonate byproduct.

“As part of this agreement with Microsoft, we can deepen our scientific research and further validate ERW under real-world conditions,” said Felix Harteneck, founder and CEO of InPlanet.

“Our team is monitoring every aspect, from soil chemistry to local water systems, to ensure each tonne of CO₂ is rigorously accounted for. The insights we gain from these deployments will improve our measurement and verification methods, setting an even higher bar for transparency in carbon removal. Ultimately, this is about building trust: we want every stakeholder to know that each credit we deliver is grounded in solid science and delivers permanent climate benefits.”

All of the credits delivered to Microsoft under the agreement will be issued under Isometric’s Enhanced Weathering Protocol and publicly listed on the Isometric Registry. The anonymized project data will also be shared through Cascade Climate’s ERW Data Quarry to improve transparency and industry-wide scientific research.

Founded in 2022, InPlanet operates across Brazil and Germany. It delivered what it said were the world’s first independently verified ERW carbon-removal credits in December 2024.

Microsoft has signed several carbon removal deals with ERW firms. In October, it announced an expanded deal with ERW company Undo to purchase 28,900 tons of carbon removal credits. The agreement was Microsoft’s third with Undo, following the purchase of 5,000 carbon credits in 2023, followed by a 15,000-ton commitment in 2024, while also committing to fund crucial scientific research.

Microsoft has also backed several other ERW firms to support its carbon removal portfolio. These include a 12,000-ton deal with US firm Terradot, an 8,000-ton deal with Eion, and an 11,400-ton deal with Lithos Carbon.