Transforming U.S. agriculture with crushed rock for CO$_2$ sequestration and increased production

TL;DR

Enhanced weathering using crushed silicate rocks on U.S. farms could sequester significant CO₂, support climate goals, and provide economic and environmental benefits, requiring bipartisan support and careful implementation.

Contribution

This study provides a detailed state-level analysis of enhanced weathering's potential for CO₂ removal and its economic, environmental, and political implications in U.S. agriculture.

Findings

EW could sequester 0.23-0.38 Gt CO₂ annually in the U.S.

Cost of CDR declines to $100-150 per ton CO₂ by 2050.

EW offers long-term CO₂ removal and climate mitigation benefits.

Abstract

Enhanced weathering (EW) is a promising modification to current agricultural practices that uses crushed silicate rocks to drive carbon dioxide removal (CDR). If widely adopted on farmlands, it could help achieve net-zero or negative emissions by 2050. We report detailed state-level analysis indicating EW deployed on agricultural land could sequester 0.23-0.38 Gt CO$_2$ yr$^{-1}$ and meet 36-60 % of U.S. technological CDR goals. Average CDR costs vary between state, being highest in the first decades before declining to a range of $\sim\$$100-150 tCO$_2{}^{-1}$ by 2050, including for three states (Iowa, Illinois, and Indiana) that contribute most to total national CDR. We identify multiple electoral swing states as being essential for scaling EW that are also key beneficiaries of the practice, indicating the need for strong bipartisan support of this technology. Assessment the geochemical capacity of rivers and oceans to carry dissolved EW products from soil drainage suggests EW provides secure long-term CO$_2$ removal on intergenerational time scales. We additionally forecast mitigation of ground-level ozone increases expected with future climate change, as an indirect benefit of EW, and consequent avoidance of yield reductions. Our assessment supports EW as a practical innovation for leveraging agriculture to enable positive action on climate change with adherence to federal environmental justice priorities. However, implementing a stage-gating framework as upscaling proceeds to safeguard against environmental and biodiversity concerns will be essential.