While enhanced weathering of rocks is a highly promising CDR method for storing CO2 permanently, scaling it up safely and effectively remains a challenge. Current research is largely confined to experiments at lab scale and few short-term field trials, leaving the long-term ecological impacts, real-world CDR quantification, and robust Measurement, Reporting, and Verification (MRV) debated.
To overcome these uncertainties, we argue that investigating natural systems that stabilized over millennia can significantly contribute to the development of EW methods.
Here, we present how natural loess weathering influences river chemistry at catchment scale, and how simple measurements can be utilized to estimate weathering rates and CDR. Remarkably, loess deposited after the last glaciation still exhibits high weathering signals today. Our research reveals that this process is heavily dominated by calcium release from carbonates – a reminder that carbonate weathering should not be overlooked in ERW applications, as its rapid reaction rates can significantly outperform mafic silicate materials.
Our study demonstrates that simple electrical conductivity (EC) measurements can be directly related to total alkalinity and flow rates. Once a system is thoroughly understood, these accessible metrics can be utilized to predict weathering and estimate CDR at scale, offering a pathway toward a highly economic and dependable MRV framework. However, this approach requires rigorous baseline data collection beforehand.
We propose that:
• investigating natural systems contribute to de-risk and accelerate the deployment of engineered CDR solutions
• simple EC measurements help quantifying weathering and CDR of EW deployments in an economic and robust way.