India-based climate tech startup Alt Carbon announced that it has raised $12 million in a seed financing round, with proceeds aimed at scaling its Enhanced Rock Weathering solution to remove and store carbon across the Global South.

According to the company, the announcement marks the largest seed round to date for climate tech in India.

Founded in 2023 by brothers Shrey and Sparsh Agarwal, Alt Carbon has set a goal to remove 5 million metric tons of CO2 by 2030, with a focus on Carbon Dioxide Removal (CDR) in South Asia, through technology pathways like Enhanced Rock Weathering (ERW). The company’s ERW method sources basalt rock dust from mines, and spreads it across agricultural fields, where it reacts naturally with rainwater through a chemical reaction that converts it into stable bicarbonate ions that are stored in the soil, and over time travel through rivers to the ocean, residing as calcium carbonate for over 10,000 years.

In addition to removing carbon, the process also improves soil health and crop yields, according to Alt Carbon. The company said that its flagship initiative, The Darjeeling Revival Project (DRP), aims to remove CO2 and to “restore livelihoods, revive degraded soils and ecosystems, and preserve India’s most valued export: Darjeeling’s tea.” In the past two months, Alt Carbon has signed a strategic partnership with Mitsubishi Corporation, and a 10,000-tonne carbon removal offtake agreement with MOL Group.

Alt Carbon said that the new capital will help expand Earth Sciences R&D, advance hardware innovations, and scale-up operations for durable climate action in India, accelerating CDR in the Global South.

Alt Carbon Co-founder & President, Sparsh Agarwal, said:

“Our goal is to make India a hub for carbon removal. We plan to remove CO2 at scale from the Global South, for the planet. We thank the partners who have joined us in this ambitious, whirlwind journey, to revive Darjeeling, remove CO2 and undo the clock for this planet.”

The seed round was led by tech investor and AI startup Physical Intelligence co-founder and CEO Lachy Groom, and included participation from existing investors.

Groom said:

“Alt Carbon is tackling a once-in-a-generation challenge. The personal journey of the founders, their technical approach, and ambitious vision will help us remove CO₂ from the atmosphere at gigaton scale — all while adapting agricultural land for climate impact. In just 18 months, the team has built a world-class lab, created proprietary models, and laid the foundation for a new class of carbon removal and agricultural infrastructure. This is a category-defining deep-tech company that will reshape how the world thinks about climate action.”