Early–Middle Holocene Evolution of Lake Ice Cover Duration in Northeast China

Seasonal temperature reconstructions provide a critical approach for reconciling discrepancies between paleoclimate model simulations and proxy records. However, cold-season temperature variations remain poorly constrained due to the scarcity of robust cold-season temperature proxies. This study provides critical insights into lake ice-covered season temperature dynamics in Northeast China, a region where cold-season climate variability has remained poorly constrained in paleoclimate reconstructions. We collected total organic carbon sequences from seven closed lakes in Northeast China over the last 10,000 years to evaluate the lake ice cover duration as a proxy for lake ice-covered season temperature during the early–middle Holocene. Our results show that the lake ice cover duration decreased from ~8 ka BP, reaching a minimum at around 4 ka BP. This pattern is linked to ice-covered season temperature changes, with warmer ice-covered seasons leading to shorter ice cover durations and increased lake productivity, which were driven by orbital forcing (seasonal insolation changes) and greenhouse gas concentrations. Orbital forcing played a dominant role in winter warming between 8 and 4 ka BP, while greenhouse gas also contributed, but to a lesser extent.