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

间冰期的结束是什么？

• 批准号: 206980909
• 负责人: Dr. Aline Govin
• 金额: --
• 依托单位: Fachgebiet Geosystem-Modellierung
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2011
• 资助国家: 德国
• 起止时间: 2010-12-31 至 2015-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/206980909?language=en
• 关键词: What; ends; Interglacial; Feedbacks; between

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.

目前的间冰期何时以及如何结束仍是一个悬而未决的问题。末次间冰期（LIG）和随后的冰川开始期具有相对已知的气候，可以揭示导致新冰期建立的气候机制。两个关键问题从已知结束LIG的气候事件链中产生：(1)活跃的热盐环流（THC）延长了间冰期北大西洋的变暖，是有利于还是推迟了北部冰盖的生长？(2)南美水汽的重新组织是否如冰河时期观测到的热带水汽反馈所表明的那样，通过维持北大西洋的咸化和活跃的THC，从而延长了北大西洋的变暖？为了解决这些问题，我们建议将新的古气候重建与气候模式实验相结合。首先，我们将通过在海洋沉积物岩心样带上应用互补代理，重建末次冰期开始时南美雨带的详细演化。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，通过将热带大西洋SSS和深水特性与模式敏感性实验进行比较，我们将改变热带淡水强迫。最后，我们将运行末次冰期开始的瞬态气候/冰盖模式，并进行敏感性研究，其中将施加不同的海洋热通量来研究北大西洋变暖延长对冰盖生长的影响。