Current rates of chemical weathering and CO₂ sequestration in Peninsular India: A review with implications for Enhanced Rock Weathering

Chemical weathering of silicate and carbonate rocks via carbonic acid acts as a natural sink for atmospheric carbon dioxide (CO 2 ). While global estimates of CO 2 removal through weathering have been derived using the geochemistry of major rivers, such assessments remain limited at the national scale, particularly in tropical regions. The current review attempted to fill this gap by compiling chemical weathering rates (CWR) and corresponding CO 2 consumption rates (CCR) across the river basins of Peninsular India, an area characterized by diverse bedrock lithology, topography, hydrology, and long-standing anthropogenic land use. The findings indicate that Peninsular India contributes an estimated 20-45 t km -2 yr⁻¹ of chemical weathering, resulting in a CCR of 2.3 × 10⁵ mol km⁻² yr⁻¹, a quantity comparable to or exceeding that of several major global nations. This review highlights that a complex interplay of lithology, climate, runoff, topography, and land use drives the spatial variability in CWR and CCR. This review also identified the major limitation, to the precise estimation of CWR and CCR, as the need for detailed investigations of the primary controlling processes, including mineral dissolution rates, kinetic versus transport limitations, and logistical uncertainties. A more comprehensive assessment is vital prior to the large-scale implementation of enhanced rock weathering (ERW), particularly in agricultural zones. Basalt-dominated river basins, across both large and small catchment scales, may represent first-order target regions for large-scale ERW deployment in Peninsular India. Given the potential of ERW to simultaneously improve soil quality and sequester a substantial amount of CO 2 , long-term field-based studies are essential to quantify its carbon-removal efficiency, assess the persistence of soil and mineralogical changes and strengthen the scientific understanding. Overall, this review recommends a clear, evidence-based roadmap for the responsible deployment of ERW in India, with emphasis on long-term field validation, quantification of durable CO₂ removal, soil and ecosystem responses, techno-economic feasibility, and appropriate policy frameworks. Such efforts will contribute meaningfully toward India’s net-zero CO 2 emissions target by 2070.