A framework to estimate climate mitigation potential for US cropland using publicly available data

Abstract

The US agricultural sector is proposed as one opportunity to contribute to greenhouse gas (GHG) emissions reductions—reductions that are needed to limit atmospheric warming to be more in line with the US Nationally Determined Contribution to the Paris Agreement. Improved management of agricultural soils can both mitigate GHG emissions and increase carbon (C) sequestration, but disagreement exists regarding what levels of adoption are possible and to what extent they may mitigate net GHG emissions. In this paper, we provide a framework for setting reasonable, short-term conservation practice adoption targets and quantifying the associated net emissions reductions. Our framework was constructed using USDA-based publicly available inventory data and mitigation potentials from the COMET-Planner tool scaled to nine farm resource regions. The framework includes 2017 levels of conservation practice adoption and two 10-year growth scenarios: business-as-usual (BAU) and accelerated adoption rates. We evaluated six cropland management practices and practices associated with Conservation Reserve Program (CRP) establishment. Based on existing (2017) census data, we estimated that 134.2 million tonnes (Mt) carbon dioxide equivalents (CO₂e) per year have been or continue to be reduced through the adoption of conservation management practices on a cumulative total of 133.5 million hectares (Mha) of cropland. Under the BAU scenario, we estimated an additional 6.2 Mha y⁻¹ of adoption could result in a reduction potential of 48.7 Mt CO₂e y⁻¹. Under the accelerated scenario, we estimated an additional 13.1 Mha y⁻¹ of adoption could result in a reduction potential of 118.5 Mt of CO₂e y⁻¹ over the next 10 years. This framework highlights three key outcomes: (1) agriculture has had a substantial impact on GHG mitigation through existing/historical adoption of six cropland management practices and conversion of lands to the CRP; (2) these shifts in adoption provide an important baseline to make future projections of changes in practice adoption given regional trends and the resulting GHG mitigation potentials; and (3) disaggregating national estimates to the farm resource region level can help to inform and prioritize programs and policies consistent with existing climate goals. Estimates reported here reflect the current state of national modeling efforts and agricultural inventory sources. As new data such as the pending 2022 Ag Census report and model enhancements are made, the framework we outline here can be used to revise and update the estimates to improve accuracy and applicability.