The threat of nuclear winter from a regional nuclear war is an existential hazard that must be addressed to ensure the shared future of humanity. Here a cross-cultural analysis of 20 societies that experienced the Late Antique Little Ice Age (ca. 536-556CE) is performed. The climatic conditions of the Late Antique Little Ice Age are strikingly similar to those modeled as resulting from a regional nuclear war employing low-yield nuclear weapons, and thus provides a context in which mechanisms of resilience to nuclear winter might be empirically identified. It is argued that broad political participation fostering bridging ties between communities, agencies, and organizations was a key elements of social resilience to the Late Antique Little Ice Age, and may indicate a means to foster resilience to nuclear winter today.