Greenhouse Gas Fluxes and Modeling from Rice Workshop

Methane (CH4) emissions from paddy fields contribute significantly to agricultural greenhouse gas (GHG) emissions, posing a critical challenge for achieving global climate goals. Despite the availability of the Tier 3 method—which utilizes process-based models and high-resolution datasets to capture variability in site-specific CH4 emissions, its application has been limited to a few countries. There is still a large gap in establishing country and regional specific emissions factors and an increasing demand to measure actual emissions from the field. These requirements are not only for country-level inventories to the United Nations Framework Convention on Climate Change (UNFCCC) but also for the emerging carbon market in the agricultural sector. Significant efforts are being invested in advancing technologies and options for targeting and supporting climate mitigation initiatives in rice systems. Measurements and monitoring are critical in setting the baseline for these initiatives and in evaluating the progress made. However, their implementation remains challenging due to limited consensus in protocols for measurements, as well as the limited accessibility of tools and technologies for measurements, modeling and monitoring of emissions.

Modeling is central to bridging experimental research data with actionable mitigation and adaptation strategies at scale. Current models can reliably simulate yield, water balance, and basic soil–nutrient interactions, but they struggle with trade-offs between methane reduction and nitrous oxide emissions, or with integrating soil carbon dynamics.

Owing to the serious impacts of the climate crisis in crop production and human health, global assessments of GHG emissions through measurements and modeling are urgently needed to accelerate efforts in developing resilient food systems in all rice-growing countries around the world. 

The “Greenhouse Gas Fluxes and Modeling from Rice Workshop” was convened to address these challenges. The workshop was held from 1–5 September 2025 at the International Rice Research Institute (IRRI), Los Baños, Philippines, jointly led by IRRI, AgMIP, and the Global Methane Hub—with support from CGIAR Climate Action and Japan’s Ministry of Agriculture, Forestry and Fisheries (MAFF).The workshop gathered more than 80 participants from 40 organizations across 25 regions and brought together perspectives from research, stakeholders engaged in national GHG inventories, UNFCCC reporting, and the carbon market.

It was delivered in a hybrid format with in-person and online participation. The workshop`s structure was composed of six plenary sessions organized to provide the general overview of the state-of-the-science in GHG measurements and modeling in rice systems and two parallel sessions that were technical focused on the overview of different methodologies in measurements and in modeling, respectively.

Participants underscored the need to bring together field flux measurements, crop simulations, and socio-economic analysis to improve forward-looking impact assessments. Such integration would enable evaluation of how mitigation and adaptation strategies affect farmers’ livelihoods, food security, and resource use, while quantifying the trade-offs and synergies among socio-economic, biophysical, and environmental outcomes.

The different presentations highlighted the data gap in mitigation efforts’ monitoring as current national data collection targets food security. Calibration and validation data for modeling are scarce, especially at regional and national scales. Workshop discussions emphasized that while rice models have advanced significantly—particularly through multi-model ensembles and AgMIP’s coordinated intercomparison efforts—gaps remain in simulating extreme events, trait- based responses, and GHG fluxes beyond methane. 5 The workshop identified several opportunities to strengthen rice GHG research and implementation and recommendations moving forward include among others: adopting FAIR (Findable, Accessible, Interoperable, Reusable) data principles; piloting joint measurement– modeling projects across diverse rice ecologies; aligning MRV requirements of carbon markets with scientific protocol; and fostering multi-stakeholder platforms that bridge researchers, governments, and private-sector actors.

Key outputs of the workshop include: 
Consensus on minimum protocols for chamber-based measurements (chamber design, sampling frequency, flux calculation, and reporting standards). 
Agreement on the need for harmonized datasets and metadata standards, including soil, water, crop, and weather variables. 
Roadmaps from four breakout groups (water management, methane modeling, management interventions, scaling/upscaling) outlining data needs, priority interventions, and collaborative actions. 
Identification of high-potential innovations such as AWD, improved fertilizer management, and integration of socio-economic models. 
Commitments to develop shared repositories and adopt common reporting templates. 

The participants have agreed to the following actionable next steps to confirm their overall commitment to high quality research to address global challenges in facing climate change: 
Continuing communication through shared platforms (e.g., SharePoint, AgMIP frameworks) and periodic follow-up meetings to track progress. 
Co-developing guidelines for GHG measurements across global rice growing areas that will support capacity building for a global network of GHG researchers and long-term flux experimental study. 
Establishing a working group to coordinate model intercomparison, protocol standardization, and joint calibration efforts. 
Launching pilot case studies in Asia, Africa, and Latin America to test harmonized protocols and scale findings. 
Selecting case studies that can be used to conduct integrated assessments of climate change, adaptation, and mitigation using the AgMIP’s MAC-B modeling framework. 
Linking workshop outcomes to policy processes, including national GHG inventories, NDC implementation, and Article 6 mechanisms.

Together, these outputs and commitments signal a strong foundation for a coordinated global effort to reduce methane emissions from rice systems, while ensuring that mitigation strategies align with adaptation goals, farmer livelihoods, and sustainable development.