SGER: Southern Andes Glacial Chronology: Test of Abrupt Global Climate Change

是什么驱动了冰川气候循环？这个基本问题是理解最近冰期全球变化的核心。PI和其他人提出，海洋-大气系统的突然重组是将轨道扰动与全球冰河时期气候变化联系起来的关键事件。这一假设对于理解过去的气候变化以及预测地球当前气候的变化具有根本性的意义。在全球范围内，主要的海洋和大气变化是在重大气候转变期间突然和同步开始的。为了验证这样的预测，PI建议比较两极半球中纬度地区冰川边缘和平衡线高度（这是大气温度变化的敏感指标）的详细古气候记录，通过最后一次冰期-间冰期过渡。在这次测试中，他寻找南半球高山冰川的精确记录。这笔拨款是为了支持获得必要的冰川记录，同时避免绘制冰碛序列的固有和耗时的赌博，从而无法进行放射性碳年龄控制。由于缺乏放射性碳测年，大多数关于高山冰川的项目都没有特别的帮助。在考察了新西兰和南美洲的南半球高山地区之后，PI提议在智利南部的前高山冰川系统覆盖的地区进行实地勘察，该冰川系统从安第斯山脉的顶峰向西延伸到智利岛。这项野外工作将包括在Chiloe岛和邻近大陆上侦察绘制Llanquihue（威斯康辛州晚期/海洋同位素阶段2）时代的多个冰碛和冲蚀体。现有的放射性碳点将与这张地图联系起来，并将对大量新的具有有机物质的地层点进行检查和定年，以确定它们是否可以提供额外的年代控制。将对间作泥炭进行花粉和孢子地层学研究。最后，PI将确定是否可以从湖泊和沼泽的基本日期获得深入山区的冰消退的最小年龄。由此产生的初步年代学将澄清南安第斯山脉的这一地区是否能够产生具有详细年龄控制的古气候记录，以检验海洋-大气突变重组的假设。因此，在南安第斯山脉进行长期研究的可行性将从这个初步的年表中浮现出来。这项工作得到了探索性研究小额拨款的支持，它很重要，因为它试图了解与人类活动相关的时间尺度上的气候变化。

What drives glacial climate cycles? This fundamental question lies at the heart of understanding global changes of recent ice ages. The PI and others have suggested that abrupt reorganizations of the ocean-atmosphere system are the key events linking orbital perturbations to global ice-age climate changes. This hypothesis has fundamental implication about understanding past climate changes as well as anticipating changes in the earth's present climate. It is suggested that major ocean and atmospheric changes begin abruptly and synchronously on a global scale during major climate transitions. To test such a prediction the PI proposes to compare detailed paleoclimatic records of glacier margins and equilibrium-line altitudes (which are sensitive indicators of atmospheric temperature changes) at mid latitudes in both polar hemispheres through the last glacial-interglacial transition. For this test, he seeks a precise Southern Hemisphere alpine glacier record. This is a grant to support obtaining the necessary glacial record while avoiding the inherent and time-consuming gamble of mapping a moraine sequence and coming up empty for radiocarbon age control. Most projects on alpine glaciation have not been particularly helpful because of lack of radiocarbon dates. After examining Southern Hemisphere alpine areas in New Zealand and South America, the PI proposes reconnaissance field work in southern Chile in the area covered by a former alpine glacier system that extended form the crest of the Andes westward to Chile Island. This field work will involve reconnaissance mapping multiple moraines and outwash bodies of Llanquihue (late Wisconsin/marine isotope stage 2) age on Chiloe Island and the adjacent mainland. Existing radiocarbon sites will be tied into this map and abundant new stratigraphic sites with organic material will be examined and dated to determine if they can yield additional chronologic control. Pollen and spore stratigraphy will be examined for intertill peats. Finally, the PI will determine if minimum ages for ice recession deep into the mountains can be obtained from basal dates in lakes and bogs. The resulting preliminary chronology will clarify whether this region of the Southern Andes is capable of producing a paleoclimatic record with the detailed age control necessary to test the hypothesis of abrupt ocean-atmosphere reorganizations. Hence, the feasibility of a long-term study in the southern Andes will emerge from this preliminary chronology. This work is supported by a Small Grant for Exploratory Research and is important because it seeks to understand climate changes on time scales relevant to human activities.