gaia-africa-project/framework-erw

Enhanced Rock Weathering economic viability across SSA # Ex-Ante ERW — Where Enhanced Rock Weathering Pays Off in Sub-Saharan Africa **A geospatial ex-ante profitability model for Enhanced Rock Weathering (ERW) with basalt across Sub-Saharan African cropland.** > **🚧 Code release pending.** The analysis behind this repository is still being finalised. This repository currently documents *what* we model, *how* the pipeline is structured, and preliminary profitability results. The full R pipeline, parameter catalogue, and final outputs will be published here once the working paper is complete. Watch/star the repo to be notified. --- ## 1. What is this project, in one paragraph? We are building a map of where in Sub-Saharan Africa it would make economic sense to spread crushed basalt rock on cropland to **(a) reduce soil acidity for farmers and (b) pull carbon dioxide out of the atmosphere at the same time**. For every grid cell of cropland across **47 SSA countries and 23 crops**, the model answers: *if a farmer spread basalt rock dust on this field, would the carbon-removal payments plus the yield improvement outweigh the cost of buying, grinding, transporting, and spreading the rock?* The model answers this under different policy assumptions — the carbon price, the cost of measurement, reporting and verification (MRV), the choice and grind size of the rock — and ranks the most promising locations first. ## 2. Why this matters Holding warming below 2 °C requires *removing* CO₂ from the atmosphere, not just emitting less (IPCC AR6 Synthesis, 2023). **Enhanced rock weathering** — spreading finely ground silicate rock, almost always basalt, on farmland — is one of the few removal pathways that is: 1. **Physically scalable** — global-cropland deployment estimates reach 0.5–2 Gt CO₂ yr⁻¹ by 2050, with the highest per-hectare potential in the warm-humid tropics (Beerling et al. 2020); 2. **A co-benefit for farmers** — basalt acts like agricultural lime, reducing soil acidity and raising yields. A US Corn-Belt trial rep …