What ends an Interglacial? Feedbacks between tropical rainfall, Atlantic climate and ice sheets during the Last Interglacial (EndLIG)

目前的间冰期何时以及如何结束仍然是一个悬而未决的问题。末次间冰期（LIG）和随后的冰期初期气候相对较为人所知，可以揭示导致新冰期建立的气候机制。两个关键的问题出现在已知的气候事件链结束LIG：（1）间冰期北大西洋温暖，延长了活跃的温盐环流（THC），有利于或延迟北方冰盖的增长？(2)南美洲水分的重组是否有助于延长北大西洋的温暖，通过维持北大西洋的咸和活跃的THC在LIG结束时，如冰川时期观察到的热带水分反馈所建议的那样？为了解决这些问题，我们建议在这里结合联合收割机新的古气候重建与气候模式实验。首先，我们将重建南美洲雨带的详细演变过程中的最后一次冰期的开端，通过应用补充代理的海洋沉积物芯样带。其次，我们将评估热带水文变化对热带大西洋海面盐度（SSS）和大西洋THC的影响，通过比较热带大西洋SSS和深水特性与模型敏感性实验，我们将改变热带淡水强迫。最后，我们将执行一个瞬态气候/冰盖模式运行的最后一次冰期的开始，和敏感性研究，在不同的海洋热通量将被施加到调查的影响，长期北大西洋温暖冰盖的增长。

When and how the present interglacial will end remains an open question. With a relatively wellknown climate, the Last Interglacial (LIG) and following glacial inception can shed some light on the climate mechanisms leading to the establishment of a new ice age. Two key questions arise from the chain of climate events known to end the LIG: (1) Did the interglacial North Atlantic warmth, prolonged by an active thermohaline circulation (THC), favor or delay the growth of northern ice sheets? (2) Did reorganizations in South American moisture contribute to prolong the North Atlantic warmth by maintaining a salty North Atlantic and active THC at the end of the LIG, as suggested by tropical moisture feedbacks observed during glacial times? To address these questions, we propose here to combine new paleoclimate reconstructions with climate model experiments. First, we will reconstruct the detailed evolution of the South American rainbelt during the last glacial inception, by applying complementary proxies on a transect of marine sediment cores. Second, we will assess the impact of tropical hydrologic changes on tropical Atlantic sea surface salinities (SSS) and the Atlantic THC, by comparing tropical Atlantic SSS and deep-water properties with model sensitivity experiments where we will vary the tropical freshwater forcing. Finally, we will perform a transient climate/ice-sheet model run for the last glacial inception, and a sensitivity study, in which different ocean heat fluxes will be imposed to investigate the effect of prolonged North Atlantic warmth on ice sheet growth.