The Anatomy of Last Glacial Maximum (LGM) Climate Change in the Southern Hemisphere Mid-Latitudes: Paleoecological Temperature Reconstructions from Terrestrial Archives

该奖项是根据2009年美国复苏和再投资法案(公法111-5)资助的。这项研究的目的是检验有关全球冰河时代驱动因素的主要假说是否解释了南半球中纬度地区的气候变化。这项研究通过重建连续的、同位素测年的古摇篮和花粉记录，确定了新西兰南部阿尔卑斯山接壤的两个地点的南部中纬度末次冰期最大气候的时间、级别和结构。关于冰期气候变化驱动因素的假设仍然模糊不清，因为最大冰期降温的时间和程度(末次冰期最大值，LGM)似乎在南北半球之间不匹配。尽管南半球日照的强度和持续时间与北半球的日照强度和持续时间不一致，但北半球的太阳辐射被认为是推动南半球气候变化的原因。仅靠北方的日照强迫不能很好地解释两个半球之间末次冰期气候变化时间上的明显不匹配。南半球中纬度地区气候变化的准确时间和大小的高分辨率记录对于了解推动全球冰川循环的力量和确定气候系统的半球间领先和滞后具有战略意义。新西兰南部的陆地档案(湖泊沉积物)是此类研究的理想之选，因为该地区对极地西风带的微妙变化非常敏感，并支持不同的植被和摇蚊(不咬人的蚊蝇)生态区。来自该地区的花粉和摇蚊与温度有已知的关系，可以提供连续的、可测得的、对陆地温度变化的定量估计。这项研究有两个主要目标：1)利用花粉和摇摆体温度推断模型，从位于冰川冰川带外的两个湖泊中重建南阿尔卑斯山西部和东部边缘的古温度；2)利用详细的AMS放射性碳测年，确定该地区末次冰川气候变化的准确时间和持续时间。该项目将提供一个全面的古气候数据集，直接适用于测试有关主要气候变化的强迫机制的假说。拟议的研究将为每学期四名本科生提供培训机会。它将发展和加强缅因州大学和几个新西兰机构之间的合作关系。对社会的好处包括记录气候现象的时间和空间范围和大小，以更好地了解中纬度南部的末次冰期气候，并测试关于驱动冰河时代变化的机制的几个假说的可行性。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The objective of this research is to test if leading hypotheses about drivers of global ice ages explain climate change in the Southern Hemisphere mid-latitudes. The research establishes the timing, magnitude, and structure of southern mid-latitude Last Glacial Maximum climate from two sites bordering the Southern Alps, New Zealand, by reconstructing temperature changes from continuous, isotopically dated, paleo-chironomid and pollen re-cords.Hypotheses about what drives ice age climate change remain clouded with ambiguities because the timing and magnitude of maximum ice age cooling (Last Glacial Maximum, LGM) does not appear to match between the Northern and Southern Hemispheres. Northern solar insolation is held responsible for driving Southern Hemisphere climate changes even though the intensity and duration of southern insolation is out of phase with that of the north. Apparent mismatches in the timing of LGM climate changes between the hemispheres cannot be adequately explained by northern insolation forcing alone. High resolution records of the precise timing and magnitude of climate change in the mid-latitudes of the Southern Hemisphere are strategic for understanding the forces driving global glacial cycles and identifying interhemispheric leads and lags in the climate system. Terrestrial archives (lake sediment) from southern New Zealand are ideal for such research because the region is sensitive to subtle changes in the circumpolar westerlies and supports distinct vegetation and chironomid (non-biting midge fly) ecological zones. Pollen and chironomids from this region have known relationships to temperature and can provide continuous, datable, quantitative estimates of terrestrial temperature change. This research has two primary goals: 1) to develop paleotemperature reconstructions for the western and eastern margins of the Southern Alps from two lakes located outside LGM moraine belts using pollen and chironomid temperature inference models, and 2) to determine the precise timing and duration of LGM climate changes for this location using detailed AMS radiocarbon dating. The project will provide a comprehensive paleoclimate data set that will be directly applicable to testing hypotheses about forcing mechanisms responsible for major climate changes.The proposed research will provide training opportunities for four undergraduate students per semester. It will develop and enhance collaborative ties between the University of Maine and several New Zealand institutions. Benefits to society include documenting the temporal and spatial extent and magnitude of climatological phenomena to better understand the LGM climate of the southern mid-latitudes and testing the viability of several hypotheses about mechanisms that drive ice age change.