Some technologies use accelerated natural processes to capture carbon – but can they store it durably? |
Natural geological processes have been regulating Earth’s climate for millions of years.
Accelerated versions of these processes are now being promoted as technologies to draw down carbon from the atmosphere – and some are rapidly moving from concept to real-world deployments.
Two such technologies are known as enhanced weathering, which speeds up the chemical breakdown of certain rocks, and ocean alkalinity enhancement, which increases the ocean’s natural ability to remove carbon dioxide from the air.
Startups backed by tech companies including Google and Microsoft are already applying these technologies in field trials. Investment in the sector is rising rapidly, with large-scale trials underway and carbon credits beginning to appear on voluntary markets.
But as our new assessment published in Science highlights, some estimates of carbon removal through these technologies may be too optimistic.
Current models assume carbon captured on land or in coastal waters will reliably make its way into long-term storage in the ocean. However, these models don’t replicate all Earth processes.
In reality, part of the engineered capture of carbon can be reversed as water moves through soils, rivers, estuaries and coastal environments. Dissolved elements can become trapped again in new minerals such as clays, reducing how much carbon ultimately remains stored over long........