Arctic sea ice has declined rapidly over recent decades, while Antarctic sea ice has exhibited an ambiguous trend. Both systems have large inter-annual variability, particularly on a regional basis. The dominant physical properties and processes driving variability are changing in ways that we do not fully understand. Refining understanding of sea ice processes is critical to improving polar environment prediction. In this session, we welcome remote sensing, field, laboratory, and modeling studies addressing processes or properties of sea ice and the cascading interactions sea ice has with the atmosphere and ocean. A special focus of this year’s session is on processes driving the inter-annual variability in sea ice systems. We anticipate that both thermodynamic processes (e.g. melt initiation) and dynamic processes (e.g. enhanced transport) govern inter-annual variability. We particularly encourage contributors to consider how ice processes and properties may control rapid changes in sea ice systems.