A large improvement in the simulation of sea ice in E3SM version 3 as compared to previous versions of the coupled model has opened the way to new and advanced saline ice physics being implemented in E3SM’s polar code.  E3SM now uses Icepack from the CICE Consortium and we are looking to expand on its capabilities as well as implementing a new sea ice dynamical core with improved coupling.  We first provide an overview of the sea ice climate in E3SM version 3, quantifying variability and bias evolution in global sea ice extent, freeboard, drift, and deformation in the late 20^th and 21^st century ensemble of the standard model. Then, drawing on current developments in the E3SM, InteRFACE, and Material Point Method SciDAC projects, we discuss the architecture of the sea ice code for E3SM version 4 that will combine several new features: i) wave-sea ice interaction to improve representation of the marginal ice zone, polar coastlines, and global ocean surface wave attenuation; ii) a variational state-space solution incorporating macro-porosity, ridge statistics, surface drag, and landfast ice; iii) variable-salinity ice-ocean coupling to improve model stability and river and iceberg coupling with MOSART; iv) tight barotropic coupling with OMEGA obeying newly derived ice-ocean stability thresholds;  v) higher spectral resolution in the radiative coupling with EAM; and finally a new Material Point Method dynamical core.  We plan to complement these features with observational emulators for several orbital missions, allowing quick and accurate evaluation of sea ice cover, thickness and roughness, as well as wave attenuation.