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。这项研究的目的是测试有关全球冰河时代驱动因素的主要假设是否能解释南半球中纬度地区的气候变化。这项研究通过从连续的、同位素测年的、古摇蚊和花粉记录重建温度变化，确定了新西兰南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、幅度和结构。关于是什么驱动了冰期气候变化的假设仍然模糊不清，因为最大冰期冷却的时间和幅度（末次盛冰期，LGM）似乎并不匹配之间的北方和南半球。北方的太阳辐射是南半球气候变化的主要驱动力，尽管南方的太阳辐射强度和持续时间与北方不同。两半球之间末次盛冰期气候变化时间上的明显不匹配不能仅仅用北方的日射强迫来充分解释。高分辨率记录南半球中纬度地区气候变化的精确时间和幅度，对于理解推动全球冰川循环的力量和确定气候系统中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）是进行此类研究的理想选择，因为该地区对绕极西风带的微妙变化很敏感，并支持不同的植被和摇蚊（不咬人的摇蚊）生态区。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，可定年的，定量的地球温度变化的估计。这项研究有两个主要目标：1）开发古温度重建的西部和东部边缘的南阿尔卑斯山从两个湖泊位于LGM冰碛带以外的花粉和摇蚊温度推断模型，和2）确定精确的时间和持续时间LGM气候变化的这个位置使用详细的AMS放射性碳测年。该项目将提供一个全面的古气候数据集，将直接适用于测试有关造成重大气候变化的强迫机制的假设。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幅度，以更好地了解南部中纬度地区的LGM气候，并测试有关推动冰河时代变化的机制的几种假设的可行性。

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.