Our field and lab-based experiment relied upon a novel approach to CO2 sequestration called Enhanced Rock Weathering (ERW). This new technique, called enhanced weathering, distributes ground up silicate minerals on agricultural soils. It pairs particularly well with grasslands, like these in the Browns Valley foothills of California. ERW fuels chemical reactions to produce geologically stable carbonate minerals. This process mimics and accelerates natural rock weathering, aiding the movement of carbon from the atmosphere into geologic formations.
The potential impact of ERW is significant. It is estimated that if this method were to be applied broadly, covering 8% of California’s total rangelands, it could sequester up to 51.7 million metric tons of carbon dioxide equivalent per year. That’s a significant investment in climate change fighting technologies that improve our ability to capture and store carbon.
Understanding Enhanced Rock Weathering
Enhanced Rock Weathering works on a concept that’s pretty simple, but super powerful. By injecting crushed metabasaltic rocks, the technique speeds up the weathering process that normally takes place over geological timescales. When you distribute these minerals throughout the soil, these minerals create chemical reactions. These reactions are followed by the conversion of carbon dioxide into stable carbonate minerals. This process not only removes carbon from the air but makes the soil healthier, providing nutrients for plants to thrive.
The use of ERW is especially a win for grassland ecosystems, which make up large swaths of California’s landscape. The Browns Valley foothills make for an ideal demonstration site where this technique could be used creatively. By focusing their efforts on areas with high concentrations of grasslands, scientists can achieve the greatest impact through this approach while improving biodiversity in local ecosystems.
Role of Organic Additives
The study’s authors found significant positive effects from adding organic additives, such as compost and biochar. This has the potential to greatly increase the cost effectiveness of carbon sequestration through ERW. These materials can enhance the chemical reactions facilitated by crushed silicate minerals, thereby boosting the overall effectiveness of the process. When ERW is paired with these organic compounds, an astounding 99.1% of carbon is captured. Along with being a carbon storage powerhouse, compost improves soil health by making nutrients more available.
Long-term post-ERW monitoring is absolutely essential to better understand how effective ERW and its organic/in-place enhancements really are. Today, researchers are seriously monitoring their FieldMetrics. For each site, they measure levels of soil organic and inorganic carbon, pore water dissolved carbon, and aboveground biomass. Finally, measuring greenhouse gas emissions will help document the overall beneficial environmental impacts of ERW practices.
Implications for Climate Action
Farmland adoption of Enhanced Rock Weathering holds great potential as a positive, bipartisan, localized solution to our climate challenges. California has an opportunity to make a major impact on our state’s greenhouse gas emissions by sequestering millions of metric tons of carbon dioxide annually. Comprehensively, this strategy will be crucial in the ongoing fight against global warming.
As scientists work to test the limits and improvement of this technique, the possibilities reach far beyond the grasslands of California. The foundational ideas behind ERW are relevant to ecosystems all across the world. This flexibility is what makes it such a potent weapon in the war on climate change.