Towards a modular multi ecosystem monitoring, reporting and verification (MRV) framework for soil organic carbon stock change assessment

Background

Soils store roughly 1,500–2,400 petagrams (Pg) of organic carbon globally, more than the combined carbon in the atmosphere and vegetation, making soil organic carbon (SOC) a critical component of climate mitigation and land degradation neutrality targets. Many initiatives assume that relatively small annual increases in SOC across large areas could offset gigatonnes (Gt) of CO2, but these claims require robust, comparable monitoring systems. Current MRV approaches often focus on single sectors and use heterogeneous methods, limiting their usefulness for cross-ecosystem accounting and results-based finance.

Goals and Methods

This paper proposes a modular MRV framework for SOC stock change that can be applied to croplands, grasslands, forests, and other ecosystems within national and project-level systems. The authors synthesize guidance from IPCC inventory methods (i.e., Tiers 1–3), long-term field experiments, and modelling tools (e.g., Century-type models) to define modules for activity data, field sampling, laboratory analysis, modelling, and uncertainty quantification. They outline sampling intensities and resampling intervals and show how the framework can be nested within national greenhouse gas inventories and carbon crediting schemes.

Conclusions and Takeaways

The proposed framework allows countries to start with simpler Tier 1-2 methods and progress toward higher-tier, measurement-rich systems, while ensuring that SOC changes of ~1-2 Mg C ha⁻¹ over a decade can be detected with quantified uncertainty. The authors argue that modular design can support integration of remote sensing and model data fusion as they mature, enabling more cost-effective coverage over millions of hectares. For practitioners, adopting such a framework can increase credibility of SOC-based mitigation claims in markets and funds, reduce transaction costs by standardizing procedures, and improve alignment between soil health programs and national climate commitments.