Abrupt cooling is observed at the end of interglacials in many paleoclimate records, but the mechanism responsible remains unclear. Using model simulations, we demonstrate that there exists a threshold in the level of astronomically induced insolation below which abrupt changes at the end of interglacials of the past 800,000 years occur. When decreasing insolation reaches the critical value, it triggers a strong, abrupt weakening of the Atlantic meridional overturning circulation and a cooler mean climate state accompanied by high-amplitude variations lasting for several thousand years. The mechanism involves sea ice feedbacks in the Nordic and Labrador Seas. The ubiquity of this threshold suggests its fundamental role in terminating the warm climate conditions at the end of interglacials.

在许多古气候记录中，在间冰期末期观察到突然冷却，但其机制仍不清楚。使用模型模拟，我们证明天文诱发的日照水平存在一个阈值，低于该阈值在过去 800,000 年间冰期结束时会发生突然变化。当日照减少达到临界值时，它会触发大西洋经向翻转环流的强烈、突然减弱和较冷的平均气候状态，伴随着持续数千年的高幅度变化。该机制涉及北欧和拉布拉多海的海冰反馈。这一阈值的普遍存在表明它在终止间冰期末期温暖气候条件方面发挥着重要作用。