[A-CG37] Global Carbon Cycle Observation and Analysis

[ACG37-05] Top-down estimation of regional emissions and removals of CO₂, CH₄ and N₂O

*Prabir Patra¹, Naveen Chandra¹, Dmitry Belikov² (1.Research Institute for Global Change, JAMSTEC, 2.Center for Environmental Remote Sensing, Chiba University)

Keywords:CO2, CH4, N2O, MIROC4-ACTM, Inverse modelling

The human induced emissions of carbon dioxide (CO₂), methane (CH₄) and nitrous oxide (N₂O), have led to strong increase of global surface air temperature (GSAT) in the past 100 years and likely to continue putting immense pressure on the future GSAT increase. Improved knowledge of their emissions and removals at regional scales will be the key for any emission reduction effort under the Paris Agreement and follow the implementation of the nationally determined contributions (NDCs). In JAMSTEC, we perform top-down estimations of regional CO₂, CH₄ and N₂O emissions and removals using the MIROC version 4.0 AGCM-based chemistry-transport model (MIROC4-ACTM) and atmospheric observations. Our top-down inversion model estimated the land and ocean sink partitioning of -7.7 and -8.8 GtCO₂ yr^-1, respectively, for 2011-2020, offsetting about 22% and 25% of global fossil-fuel CO₂ emissions (35.5 GtCO₂ yr^-1). Global CH₄ emissions and chemical loss were estimated at 585 and 540 MtCH₄ yr^-1, respectively. Global N₂O emissions and photochemical loss were estimated at 27.0 and 20.1 MtN₂O yr^-1, respectively, for 2011-2020. Our assessments (Chandra et al., JMSJ, 2021; Patra et al., JMSJ, 2022; Chandra et al., in review, 2021) suggest the Asian regions are driving the fastest emission increase for total (radiative forcing weighted) greenhouse gases emissions.