[A-CG39] グローバル炭素循環の観測と解析

[ACG39-08] Methane Inversion Inter-Comparison for Asia (MICA): Improving Regional CH₄ Emission Estimates to Support Climate Mitigation Efforts

*Fenjuan Wang¹、Shamil Maksyutov¹、Rajesh Janardanan¹、Dmitry A. Belikov²、Prabir K. Patra³、Ruosi Liang⁴、Yuzhong Zhang⁴、Ge Ren⁵、Hong Lin⁵、Nicole Montenegro⁶、Antoine Berchet⁶、Marielle Saunois⁶、Adrien Martinez⁶、Sara Hyvärinen⁷、Aki Tsuruta⁷、Samuel Takele Kenea⁸、Tsuneo Matsunaga¹ (1.NIES National Institute of Environmental Studies, Japan、2.Chiba University, Japan、3.Japan Agency for Marine-Earth Science and Technology, Japan、4.Westlake University, China、5.National institute of metrology of China、6.Laboratory for Climate and Environmental Sciences, France、7.Finnish Meteorological Institute, Finland、8.National Institute of Meteorological Sciences, Korea)

キーワード：Methane, Inverse Modeling intercomparison, Asia

Methane (CH₄), a potent greenhouse gas with a relatively short atmospheric lifetime of about 9 years, plays an important role in climate forcing. Mitigating anthropogenic CH₄ emissions is essential to achieving the Paris Agreement targets, as underscored by the goal of the Global Methane Pledge to achieve a 30% reduction by 2030. This study presents the Methane Inversion Inter-Comparison for Asia (MICA), a multi-model inverse modeling initiative designed to evaluate CH₄ emissions at regional and national scales across East, South, and Southeast Asia. These regions, home to over half of the global population, are major contributors to global CH₄ fluxes. However, national emission reporting to the UNFCCC remains incomplete and is often associated with significant uncertainties.

MICA aims to enhance the accuracy and precision of country-level CH₄ flux estimates by assimilating atmospheric observations across multiple inverse models. The intercomparison focuses on four key objectives: (1) quantifying emission trends, (2) partitioning sectoral contributions from anthropogenic and natural sources, (3) characterizing associated uncertainties, and (4) assessing the added value of integrating satellite-derived XCH₄ observations. Results from seven participating inverse models will be presented, highlighting regional emission patterns and their implications for climate policy.

By providing robust, observationally constrained multimodel CH₄ flux estimates, MICA would support improvements in national greenhouse gas inventories reported to the UNFCCC. Furthermore, this work will facilitate an independent evaluation of the Global Stocktake and support the development of targeted and effective CH₄ mitigation strategies.