[A-CG35] Projection and detection of global environmental change

[ACG35-11] Compatible Fossil Fuel CO₂ Emissions in the CMIP6 Earth System Models’ Historical
and Shared Socioeconomic Pathway Experiments of the Twenty-First Century

★Invited Papers

*Spencer Liddicoat¹, Andy Wiltshire¹, Chris jones¹, Vivek Arora², Victor Brovkin³, Patricia Cadule⁴, Tomohiro Hajima⁵, David Lawrence⁶, Julia Pongratz⁷, Jörg Schwinger⁸, Roland Séférian⁹, Jerry Tjiputra⁸, Tilo Ziehn¹⁰ (1.Met Office Hadley Centre, Exeter, United Kingdom, 2.Canadian Centre for Climate Modelling and Analysis, Environment Canada, University of Victoria, Victoria, British Columbia, Canada, 3.Max Planck Institute for Meteorology, Hamburg, Germany, 4.IPSL, CNRS, Sorbonne Université, Paris, France, 5.Research Institute for Global Change, Japan Agency for Marine-Earth Science and Technology, Yokohama, Japan, 6.Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, Colorado, 7.Ludwig-Maximilian University, Munich, Germany, 8.NORCE Norwegian Research Centre, Bjerknes Centre for Climate Research, Bergen, Norway, 9.CNRM, Université de Toulouse, Météo-France, CNRS, Toulouse, France, 10.CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia)

Keywords:Carbon cycle, Earth System Model, CO2 Emissions

This presentation will show the fossil fuel (FF) CO₂ emissions diagnosed from the historical and future simulations of nine Earth System Models participating in CMIP6 (Coupled Model Intercomparison Project, Phase 6). The future scenarios represented are the Shared Socioeconomic Pathways (SSPs) of the ScenarioMIP project. The multimodel mean FF emission rate matches the historical record well and cumulative historical emissions are close to the observations-based estimate. Only two models fall inside the observed uncertainty range, however; while two exceed the upper bound, five fall slightly below the lower bound, due primarily to the plateau in CO₂ concentration in the 1940s. For the future scenarios, the ESMs’ diagnosed FF emission rates are consistent with those generated by the integrated assessment models (IAMs) from which the SSPs’ CO₂ concentration pathways were constructed; the IAMs’ emissions lie within the ESMs’ spread for seven of the eight SSP experiments, the other being only marginally lower, providing confidence in the relationship between the IAMs’ FF emission rates and concentration pathways. The ESMs require fossil fuel emissions to reduce to zero and subsequently become negative in SSP1-1.9, SSP1-2.6, SSP4-3.4, and SSP5-3.4over. We also present the ocean and land carbon cycle responses of the ESMs in the historical and SSP scenarios.