| Summary: | Paleoclimate records show that the end of the last interglacial (MIS-5e) was marked by abrupt cooling events and other abrupt climate changes such as abrupt weakening of the Asia summer monsoon. Strong abrupt cooling occurring when the climate was still in a warm condition is puzzling and its cause remains uncertain. Our LOVECLIM1.3 transient simulations covering the period 133ka-111ka show that there exists a threshold in the astronomically-induced slow variation of insolation below which abrupt changes at the end of MIS-5e occur. When the summer insolation in the Northern Hemisphere (NH) high latitudes decreases to a critical value, it triggers a strong, abrupt weakening of the Atlantic meridional overturning circulation (AMOC) and a strong cooling in the NH followed by high-amplitude variations. The mechanism involves sea ice feedbacks in the Northern Nordic Sea and the Labrador Sea. Similar abrupt oscillations happen in the simulated temperature, precipitation and vegetation from low to high latitudes as well as in the NH snow and sea ice. Taking into account age uncertainty in the proxy records, the timing of the abrupt cooling in our model (119.8ka) corresponds well with the timing of abrupt changes observed in many marine and terrestrial records, such as the Greenland ice core records, various marine records in the North Atlantic, the Chinese speleothem and loess records and some lacustrine records in low and high latitudes. Our simulations for the other interglacials of the past 800ka show that the insolation threshold occurred also at the end of other interglacials, suggesting its fundamental role in terminating the warm condition of the interglacials.
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