Understanding past sea ice dynamics is key to anticipating future Earth system change. As sea ice declines in our warming world, this session invites studies on paleoclimate records that advance insight into sea ice processes and their climate coupling. We welcome contributions spanning a wide range of timescales from multi-century to glacial–interglacial. We particularly encourage studies focusing on climate periods of relevance to current climate change scenarios, including colder and warmer-than-modern states. Submissions may include new or refined reconstructions using marine, terrestrial, or ice cores, and proxies such as biomarkers (e.g. HBIs), halogens, water isotopes, sea salt, microfossils (e.g., diatoms, foraminifera), and IRD or model–data studies linking sea ice change with temperature, moisture, or ocean circulation. We invite work on sea ice as both a climate driver and responder, integrating other climate data and associated feedback.