Cutting the Gordian Knot – Reliable, low-cost quantification of CO2 removal and GHG mitigation in agricultural soils

Abstract:

It’s increasingly acknowledged that to achieve a global emissions pathway that can meet the goal of < 2^o C mean global warming will require not only rapid and sustained reductions in fossil fuel use and greenhouse gas emissions but also active measures to remove and sequester atmospheric CO₂. Managing soils to increase organic matter stocks is one option that can contribute to C removal targets, while at the same time improving soil health and sustainability. Although CO₂ removal via soil management at Pg scale is feasible, doing so will require mobilizing and incentivizing millions of farmers and ranchers around the world. A variety of policy options to incentivize C sequestering practices exist but all policy options will require robust, low-cost, transparent and unbiased systems to quantify and monitor soil C stock changes (and the land use practices employed) over time. Here I outline current approaches for field- to regional-scale quantification of soil C emissions and removals driven by changes in agricultural land use and management practices. Data availability and constraints are reviewed and recommendations for improvements given. Potential approaches for improved quantification, via combined model- and measurement-based systems, including data assimilation and machine-learning techniques, are examined.