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Abstract. The University of Victoria Earth System Climate Model (UVic ESCM) ofintermediate complexity has been a useful tool in recent assessments oflong-term climate changes, including both paleo-climate modelling anduncertainty assessments of future warming. Since the last official releaseof the UVic ESCM 2.9 and the two official updates during the last decade,considerable model development has taken place among multiple researchgroups. The new version 2.10 of the University of Victoria Earth SystemClimate Model presented here will be part of the sixth phaseof the Coupled Model Intercomparison Project (CMIP6). More precisely it willbe used in the intercomparison of Earth system models of intermediatecomplexity (EMIC), such as the C4MIP, the Carbon Dioxide Removal and ZeroEmissions Commitment model intercomparison projects (CDR-MIP and ZECMIP,respectively). It now brings together and combines multiple modeldevelopments and new components that have come about since the lastofficial release of the model. The main additions to the base model are(i) an improved biogeochemistry module for the ocean, (ii) a vertically resolvedsoil model including dynamic hydrology and soil carbon processes, and (iii) arepresentation of permafrost carbon. To set the foundation of its use, wehere describe the UVic ESCM 2.10 and evaluate results from transienthistorical simulations against observational data. We find that the UVicESCM 2.10 is capable of reproducing changes in historical temperature andcarbon fluxes well. The spatial distribution of many ocean tracers,including temperature, salinity, phosphate and nitrate, also agree well withobserved tracer profiles. The good performance in the ocean tracers isconnected to an improved representation of ocean physical properties. Forthe moment, the main biases that remain are a vegetation carbon density thatis too high in the tropics, a higher than observed change in the ocean heatcontent (OHC) and an oxygen utilization in the Southern Ocean that is too low.All of these biases will be addressed in the next updates to the model.
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