“…To this end, we take a specific version of the terrestrial component of the IPSL global Earth System model (ESM) ORCHIDEE (Organising Carbon and Hydrology In Dynamic Ecosystems), one that is specifically coded for, calibrated with and evaluated on high latitude phenomena and permafrost processes, called ORCHIDEE-MICT (Guimberteau et al, 2018). This code is then adapted to include DOC production in the soil (ORCHIDEE-SOM, (Camino-Serrano et al, 2018)), 'priming' of SOC (ORCHIDEE-PRIM, (Guenet et al, 2016(Guenet et al, , 2018) and the riverine transport of DOC and CO2, including in-stream transformations, carbon and water exchanges with wetland soils and gaseous exchange between river surfaces and the atmosphere (ORCHILEAK, (Lauerwald et al, 2017)). The resulting model, dubbed ORCHIDEE MICT-LEAK, herafter referred to as MICT-L for brevity, is therefore able to represent: (a) Permafrost soil and snow physics, thermodynamics to a depth of 38m and dynamic soil hydrology to a depth of 2m; (b) Improved representation of biotic stress response to cold, heat and moisture in high latitudes; (c) Explicit representation of the active layer and frozen-soil hydrologic barriers; buildup of soil carbon stocks via primary production and vertical translocation (turbation) of SOC and DOC; (d) DOC leaching from tree canopies, atmospheric deposition, litter and soil organic matter, its adsorption/desorption to/from soil particles, its transport and transformation to dissolved CO2 (CO * 2(aq.))…”