Global methane emissions from rice paddies: CH4MOD model development and application

Abstract

Rice cultivation constitutes a significant anthropogenic methane (CH₄) source and a crucial target for CH₄ mitigation. However, global and regional emissions remain poorly constrained. In this study, we validated a global-process-based methane model for rice paddies (CH4MOD), analyzed the sensitivity of major emission drivers, and simulated management scenarios involving four water regimes and three organic matter amendments. CH4MOD simulations achieved a correlation coefficient of 0.76 across 986 CH₄ flux observations globally, demonstrating its capability under different environmental conditions and management practices. The sensitivity analysis revealed water regime as the primary driver, followed by organic matter amendment and temperature. Under different crop management, CH₄ emissions varied significantly from 8 to 78 Tg CH₄/yr. This wide range of emissions demonstrates the need to use and improve rice-specific emission models and spatiotemporal data on rice distribution, water, and residue management for accurately assessing local to global emissions and their climate mitigation potential.