Modeled changes in lake ice phenology affect winter economic activities in Northeast China

Lake ice phenology in Northeast China mediates regional climate interactions and sustains winter tourism and fisheries. However, sparse long-term observations limit our understanding of ice cover trends under climate warming. Here, we combine a one-dimensional thermodynamic lake model with machine-learning residual correction and train and validate the model with satellite-derived ice phenology data from 32 lakes during 2001–2014 to simulate lake ice phenology from 1901–2100 through historical hindcasts and CMIP6 projections (SSP126, SSP370, and SSP585). Results show a marked shift toward later freeze-up, earlier break-up, and shorter ice duration beginning in the 1970s. Across the three scenarios, regional air temperatures are projected to increase by 1.2–8.1 °C century⁻¹, whereas the mean ice duration decreases by 13.6–49.8 d century⁻¹. Under SSP585, historically extreme conditions are projected to become the new phenological state, implying increasing pressure on ecosystem management and seasonal planning for winter economic activities.