Causes and effects of climate variations and rapid hydrological shifts in the northern Neotropics during the last glacial/interglacial cycle

两个ICDP站点Chalco湖（墨西哥中部）和Petén Itza湖（危地马拉北方）的沉积物记录为研究北方新热带大陆气候变化的影响和原因提供了独特的机会。尽管地理位置接近，但这两个记录表明，在末次冰期/间冰期循环期间，特别是在85至50 ka BP期间，末次冰期最大期（LGM）和Heinrich Stadial 1（HS 1）存在显著的区域间差异。这强调了这两个网站在气候系统中的关键地位，因此，我们建议结合联合收割机多代理重建与古气候建模解开时空气候演变的北方新热带地区，全球气候动态的最重要的区域。我们将结合联合收割机，生物标志物和脂质古温度计分析与古生物指标和古气候模拟在末次冰期/间冰期循环，以评估（1）气候突变的影响，通过量化的幅度和速度的生态变化，在水生和陆地生态系统（例如，在HS 6-1期间）和（2）如何转换大西洋经向翻转环流（AMOC）或太平洋环流（POC）的（中断和恢复），特别是在冰消期、冷事件和暖期，影响了北方新热带地区的区域气候和生态系统结构。我们主要感兴趣的是确定北方新热带地区气候变化和快速水文变化背后的原因和机制。为此，基于代理的重建过去的气候变率从佩滕伊察湖和查尔科湖记录将与那些战略选择的大陆和海洋记录，以便把我们的结果在跨区域的背景下进行比较。潜在的气候强迫机制最终将通过使用社区地球系统模型（CESM 1）的高分辨率古气候模拟进行测试，这些模拟显示了记录中对比鲜明的气候条件。总体而言，该项目将有助于大大提高对大西洋和太平洋环流在过去135 ka中调节北方新热带气候的作用和时间的理解，以及确定两个ICDP站点过去的生态系统如何快速响应并从这些强加的水文变化中恢复。这对于更好地了解新热带地区的敏感生态系统将如何反应和适应未来预期的干燥和温暖的气候至关重要。

Sediment records from the two ICDP sites Lake Chalco (central Mexico) and Lake Petén Itzá (northern Guatemala) provide the unique opportunity to study effects and causes of continental climate change in the northern Neotropics. Despite their geographical vicinity, both records indicate significant interregional differences during the last glacial/interglacial cycle, in particular during ~85 to 50 ka BP, the Last Glacial Maximum (LGM) and Heinrich Stadial 1 (HS1). This underscores the key position of both sites in the climate system and therefore, we propose to combine multi-proxy reconstructions with paleoclimate modeling to disentangle the spatiotemporal climatic evolution of the northern Neotropics, a region of utmost importance for global climate dynamics. We will combine bulk-geochemical, biomarker and lipid paleothermometer analyses with paleobioindicators and paleoclimatic simulations over the last glacial/interglacial cycle in order to assess (1) the effects of abrupt climate variation by quantifying the magnitude and rate of ecological changes in aquatic and terrestrial ecosystems (e.g. during HS 6-1) and (2) how shifts (disruptions and recoveries) of the Atlantic Meridional Overturning Circulation (AMOC), or Pacific Ocean Circulation (POC) especially during the deglaciation, cold events and warm periods, affected regional climates and ecosystem structures in the northern Neotropics. We are mainly interested in determining the causes and mechanisms behind climate variations and rapid hydrological shifts in the northern Neotropics. For this, the proxy-based reconstruction of past climate variability from the Lake Petén Itzá and the Lake Chalco records will be compared with those of strategically selected continental and marine records in order to put our results in a transregional context. Potential climate forcing mechanisms will finally be tested by high-resolution paleoclimate simulations using the Community Earth System Model (CESM 1) for periods that show contrasting climatic conditions among records. Overall, this project will contribute to a significantly enhanced understanding of the role and timing of the Atlantic and the Pacific Ocean circulation in modulating northern neotropical climate over the last 135 ka as well as in determining how fast past ecosystems at both ICDP sites responded to and recovered from these imposed hydrological changes. This will be essential to better understand how the sensible ecosystems of the neotropics will react and adapt to the expected dryer and warmer climate in the future.