Background

Methane (CH4) is 30 times stronger than carbon dioxide as an absorber of infrared radiation. Reducing CH4 emissions would be an effective option for rapid climate change mitigation, particularly on a decadal timescale. According to the Intergovernmental Panel on Climate Change (IPCC), atmospheric CH4 has been regrowing in concentration since 2007, which is largely driven by emissions from fossil fuels and agriculture.

CH4 emissions from rice paddies are estimated to be about 8% of total global anthropogenic methane emissions. CH4 emissions from rice paddies can vary depending on the number and duration of crops grown, water regimes, soil type, temperature, and rice cultivar. Methods such as Alternate Wetting and Drying (AWD) have been found to be effective in reducing methane emissions.

Objectives

An accurate assessment of CH4 emissions is necessary for achieving sustainable rice cultivation. Hence, the CH4Rice project aims to:

• Climate change mitigation such as carbon credit through Implementation of CH4 Monitoring, Reporting and Verification (MRV) using satellite and in-situ data.
• Manage water efficiently through irrigation methods that result in lower CH4 emissions, such as Alternate Wetting and Drying (AWD) and water saving irrigation.
• Promote and participate in regional and global sustainable agriculture related initiatives, such as SDG Goal 2, COES, GEOGLAM/Asia-RiCE and AOGEO.

Project Leader: Vietnam National Space Center (VNSC)

Activities

The work plan for implementation activities were developed and confirmed at the SAFE Executive Board Meeting in 2023. Most of the study sites have been finalized while some are under selection.

The ongoing activities include:

• Water inundation monitoring using L-band SAR and in-situ data
• Selection of study areas
• Data sharing for collaborations.

The following activities are being planned:

• Tools and knowledge sharing and capacity building for multilateral collaborations
• Promote dialogue with stakeholders and end-users by presenting results
• Synergies with SAFE Agromet and Rice Monitoring projects

Development of Methodology to Estimate CH4 Emissions from Rice Paddies

The CH4 emission estimation from rice paddies use the bottom-up approaches, as outlined by the IPCC in 2006. CH4 emission factors are multiplied by the cultivation period and harvested area to provide a final estimate. Note that using the Tier 1 method does not take into account country-specific emission factors. This will involve the disaggregation of the annual harvest area of rice for at least three baseline water regimes including irrigated, rainfed, and upland. Meanwhile, the Tier 2 method takes into account country-specific emission factors. This will involve the same steps as the Tier 1 method, but using country-specific emission factors.

  Selected Study Area (as of 6th March 2024)

Data, Tool and Knowledge Sharing and Capacity Building for Multilateral Collaborations

The following activities are being planned:

• Assessing the entire region by gathering results from each country/region.
• Sharing satellite data, such as ALOS-2 (both full-pol and ScanSAR dual), NISAR, etc.
• Sharing methodology and tools on platforms such as ISRO’s VEDAS (Visualisation of Earth Observation Data and Archival System), Google Earth Engine (GEE), Open Data Cube (ODC), and creating tutorial materials.

Promoting Dialogue with Stakeholders and End-users by Presenting Results

Planned activities include:

• Taking into account national policy and attempting to connect with relevant agencies, such as agriculture, environmental, and water management-related ministries in each country.
• Contributing to international initiatives like the Asia-RiCE/GEOGLAM, CEOS, AO-GEO and ASEAN SCOSA.
• Engaging in dialogue with organizations such as the Japan International Cooperation Agency (JICA), the Asian Development Bank (ADB), and the Japan International Agriculture Fund (JAIF).
• Building collaborations with international initiatives related to CH4 emissions, such as UNEP and the International Methane Emissions Observatory (IMEO).

Synergies with SAFE Agromet and Rice Monitoring Projects

Synergies with SAFE Agromet and Rice Monitoring Projects are imperative to optimize the use of resources and obtain mutual benefits. Existing bilateral activities and collaborations will prove to be valuable. Improved rice area maps from the Rice Crop Project will increase the accuracy of methane emission estimations.

⁠Agromet project

  https://www.eorc.jaxa.jp/SAFE/project/agromet/

⁠Rice Monitoring Project

  https://www.eorc.jaxa.jp/SAFE/project/ricecrop/