Over the past decade, there has been a growing push to address the threat of climate change. Consumers are increasingly opting for sustainable alternatives – electric cars, shoes made out of recycled materials, metal straws, reusable grocery bags – all of which have become widely available.

Despite these changes, CO2 levels are rising steadily, causing many to look to innovative solutions to counteract climate change. 

Carbon capture – the process of drawing carbon dioxide out of the atmosphere – is one solution that shows promise. 

>>>READ: The Climate Importance of Carbon Capture

Each year, we produce billions of tons of carbon dioxide (38 billion tons in 2020) by burning fossil fuels. While the Earth’s carbon cycle would naturally pull down some of this CO2, the process can take hundreds to thousands of years. Carbon capture technologies are looking for ways to speed up this process.  

Lithos and The Power of Basalt

Lithos Carbon, a start-up out of Seattle, is using Enhanced Rock Weathering (ERW) to sequester carbon from the atmosphere. ERW involves spreading crushed basalt (a common type of volcanic rock) over farmlands. The basalt mixes with rainwater to convert CO2 to dissolved bicarbonate. Lithos estimates that 3 tons of basalt can capture up to 1 ton of carbon dioxide.

ERW has a number of upsides. For one, the process is beneficial to plants, providing nutrients to the soil like iron and magnesium, as well as working to reverse acidification from fertilizers. Limestone is already being used for this purpose and could be replaced by basalt as a carbon-negative substitute. 

Similarly, dissolved bicarbonate can help neutralize ocean acidity. Bicarbonate from ERW moves from runoff to streams and rivers until finally ending up in the ocean. There, it reacts to form calcium carbonate minerals that are stable for thousands of years. 

Finally, ERW provides farmers with a new way to monetize their land. As pressures from climate change continue to push companies and governments towards carbon neutrality, the demand for sequestered carbon will continue to rise. Through companies like Lithos, farmers will be able to use their land to provide an increasingly valuable service: the ability to pull down carbon dioxide. 

Challenges and Risks of Enhanced Weathering

A full risk assessment and testing of ERW at scale has yet to be done to determine the potential risks to local ecosystems. Interfering with natural cycles is inherently risky, and it remains unclear whether ERW, if widely implemented, would have some negative effect on soil, streams, or oceans.

Ultimately, the success of Lithos depends on its ability to validate the amount of carbon sequestered through ERW. Other methods of carbon capture, like direct air capture, involve closed systems where carbon can be measured directly.

ERW, on the other hand, involves an open-system, meaning the carbon drawn from the atmosphere ends up in the earth and eventually the ocean floor. Lithos claims to have a rigorous method for verifying the amount of carbon dioxide sequestered, a method they are currently guarding as proprietary. Nonetheless, the start-up’s ability to win over investors signals that its solution has substance. 

>>>READ: Largest U.S. Industrial-Scale Direct Air Capture Plant to be Built by 2023

Lithos received its first carbon purchase this year from Frontier, a financial collective consisting of Stripe, Shopify, Meta, Alphabet, and McKinsey Sustainability. The purchase was for 640 tons of carbon offsets and was part of an investment from Stripe totaling $2.4M across 6 different companies. 

Although Lithos’ technology is new and somewhat unproven, it shows great promise to meaningfully reduce emissions. Our output of carbon dioxide is increasing every year and the amount that has already accumulated is dangerously high. Sequestering carbon from the atmosphere may be our best chance to combat climate change, achieve carbon neutrality, and start to remove the build-up of atmospheric CO2.

Luke Brennan is a writer and software developer originally from Pittsburgh. 

The views and opinions expressed are those of the author’s and do not necessarily reflect the official policy or position of C3.