5:15 PM - 6:45 PM
[ACG46-P06] Climate-biogeochemical feedback on atmospheric methane: Impacts of wetland methane and biogenic volatile organic compounds
Keywords:Methane, Earth System Model, Atmospheric Chemistry
Relatively short atmospheric lifetime of methane has promised the potential for mitigating climate change by methane emission reductions. Future climate impacts of long-lived greenhouse gases including methane have been projected by climate models with the concentration pathways which is derived from emulators. However, future methane concentration pathways remain uncertain owing to a lack of evaluation of methane cycles in emulators using emission-driven simulations with earth system models. This study assesses future changes in methane cycles which account for climate-biogeochemical feedback including wetland methane and biogenic volatile organic compounds (BVOCs) sources. To that end, we conducted future projections under SSP1-2.6 and SSP3-7.0-lowNTCF scenarios using the MIROC-ES2L earth system model (Hajima et al., 2020) coupled with the CHASER atmospheric chemistry module (Sudo et al., 2002) (MIROC-ES2L-CHEM). We find that climate-biogeochemical feedback increases global-mean methane concentrations by 7% (by 11%) and by 8% (by 33%) in 2050 (2100) under the SSP1-2.6 and SSP3-7.0-lowNTCF scenarios, respectively, resulting from increases in natural methane sources and decreases in atmospheric methane sinks. These methane increases due to climate-biogeochemical feedback correspond to the radiative forcing of 50 mW m-2 in 2050 under the SSP1-2.6 and SSP3-7.0-lowNTCF scenarios. Furthermore, methane radiative forcing is doubled from 180 to 370 mW m-2 by climate-biogeochemical feedback at the end of the 21st century under the SSP3-7.0-lowNTCF scenario. These results suggest the need to fully consider methane cycles in emulators and evaluate them with earth system models.