Comment on egusphere-2023-1477

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Hector, an open-source reduced complexity climate-carbon cycle model. Hector is a computationally efficient source of climate information, capable of completing a run in a fraction of a second. Hector models critical Earth system processes on a global and annual basis. Here we present an updated version of the model, Hector V3.1.1 (hereafter Hector V3). In this manuscript, we document Hector's new features, and implementation of new science (e.g., radiative forcing calculations, carbon cycle, etc.). Hector V3 results are in good agreement with historical observations of CO2 concentrations and global mean surface temperature, and its future temperature projections are consistent with more complex Earth System Model output data from the Sixth Coupled Model Intercomparison Project. We document that Hector V3 is a flexible, performant, and robust simulator of contemporary and 21 st -century global climate, and in closing, discuss future areas of improvement and research with respect to the model's scientific, stakeholder, and educational priorities. Reduced complexity climate models (RCMs) fill a critical role within the diverse climate modeling landscape (Sarofim et al., 2021) . By operating at lower resolutions with strategically simpler representations of large-scale climate processes and dynamics in contrast to coupled Earth System Models (ESMs), RCMs are computationally-efficient sources of future climate projections, able to produce large ensembles of results, often exploring key uncertainties, at a fraction of the computational cost of a single ESM run (Kawamiya et al., 2020) . For this reason, RCMs such as Hector, MAGICC, FaIR, and the other