Enhanced Rock Weathering as a Climate Solution?
In the quest to address climate change, scientists are exploring innovative solutions beyond reducing greenhouse gas emissions. One promising approach gaining attention is "enhanced rock weathering," which harnesses the natural process of basalt weathering to remove carbon dioxide from the atmosphere and help cool our planet. While reducing emissions remains a priority, experts argue that carbon dioxide removal is also crucial to mitigate the risks of global warming.
The United Nations recognizes that greenhouse gas reductions alone may not be sufficient to curb dangerous temperature increases. Therefore, carbon dioxide removal techniques are needed to actively extract CO2 from the atmosphere. While tree planting is a natural method of carbon capture, it has limitations, as the captured carbon is released when the trees decompose or burn. Additionally, there are constraints on the widespread implementation of tree-planting initiatives.
Enhanced rock weathering offers a middle ground between natural and man-made approaches. It accelerates the gradual weathering process of basalt, a common volcanic rock, to enhance carbon removal. Basalt naturally weathers over time, removing carbon dioxide from the atmosphere. However, the process can be amplified by increasing the surface area contact between rainwater and basalt fragments, thereby boosting weathering and carbon removal.
Jim Mann, founder of the enhanced rock weathering company UNDO, is utilizing this technique to combat climate change. With £12 million in new investment secured, UNDO aims to scale up operations. While standing in a quarry near Edinburgh, surrounded by heavy machinery, Mann demonstrates the power of basalt by rubbing tiny black rocks between his fingers. The residual basalt from the quarry, which would otherwise go to waste, can be used for carbon removal.
Traditionally, volcanic rocks and cliffs have slowly removed carbon through weathering in rainfall. Enhanced rock weathering takes advantage of finely crushed basalt to increase weathering and carbon uptake. To optimize carbon removal, the basalt fragments need to be spread over a larger area. Local farmers play a crucial role in this process. By spreading the basalt on their fields, they not only contribute to carbon removal but also benefit from improved crop yields and grazing quality.
The practicality of enhanced rock weathering is evident as farmers scatter the basalt on fields without requiring specialized equipment. A tractor pulls a trailer loaded with basalt, dispersing the tiny rocks using a rotating wheel. Farmers, like John Logan, who witnessed UNDO's trials on neighboring farms, embrace the concept. Logan expects better grass for his cattle due to the improved quality of the basalt-treated fields.
While some experts express concerns that carbon removal techniques might divert attention from emission reductions, Mann emphasizes the necessity of CO2 reduction as a primary focus. However, he highlights the importance of developing scalable technologies for carbon removal. Enhanced rock weathering offers a permanent solution, providing a significant advantage over other methods.
The numbers associated with enhanced rock weathering are daunting. UNDO's scientists estimate that capturing one tonne of CO₂ requires four tonnes of basalt rocks. Considering the average annual CO₂ emissions of a British citizen, approximately seven tonnes, each individual would need around thirty tonnes of basalt (equivalent to one and a half trailer loads) per year to achieve carbon neutrality.
Despite the challenges, UNDO aims to rapidly expand its operations, receiving support from influential backers. Microsoft, for example, has committed to funding the scattering of 25,000 tonnes of basalt on UK fields. In addition to financial support, Microsoft will assist in auditing and verifying the effectiveness of the project.
Dr. Smith envisions the integration of enhanced rock weathering into conventional farming practices, where it can provide carbon removal benefits alongside food and crop production. However, scalability remains a key question. If the process is massively expanded, the energy and emissions associated with grinding, transporting, and scattering basalt must be carefully considered.
Jim Mann remains optimistic, viewing the current stage of enhanced rock weathering as a win-win scenario for all parties involved. UNDO aims to spread 185,000 tonnes of basalt this year, with a goal of removing one million tonnes of CO₂ by 2025.
Reference: Can ‘enhanced rock weathering’ help combat climate change? - BBC News
