All comprehensive Earth System models (ESMs) include Land components, which simulate canopy temperature and humidity; soil moisture, ice, and temperature; snow as well as many biogeochemical fluxes between atmosphere, plants and soils. ESMs capture sub-grid land heterogeneities, which arise from land-use, geomorphology, fires and vegetation dynamics. Typically, all sub-units within a land grid receive the same downward fluxes of radiation and precipitation from an atmospheric grid. ESMs assume that the canopy air is clean and ignore tracers that may be present in the canopy air (e.g. dust or fire emissions). Parameterizations have been developed to capture effects of mountains, vegetation structures and snow impurities on the surface radiation budget. Such parameterizations have been evaluated in stand-alone land, regional, and global atmospheric models. However, no complete and inherently consistent land surface radiation transfer treatment (e.g. mountains, multi-layer canopy, and snow) has been implemented in any CMIP6-class ESMs.