We investigate the relationship between climatic and demographic events in Korea during the Chulmun period (10,000–3,500 cal. BP) by analyzing paleoenvironmental proxies and 14C dates. We focus on testing whether a cooling climate, and its potential impact on millet productivity around 4,500 cal. BP triggered the population decline observed in the archaeological record. We employ a Bayesian approach that measures the temporal relationship between climatic events and change-points in the rate of growth in human population as inferred by radiocarbon density. Our results do not support the climate-induced population decline hypothesis for three reasons. First, we could not determine that the cooling climatic event necessarily preceded the reversal point in population growth rate as inferred by the radiocarbon record. Second, we did not find evidence showing a significant reduction of millet-associated dates occurring during the cooling climate. Third, we detected a spatially differentiated pattern of decline in inland and coastal regions, indicating that the cooling climate did not impact all populations equally. We highlighted the long tradition of mobility-based subsistence strategy in the coastal region as a potential factor contributing to the spatial differences.