Collaborative Research: Quantitative Estimates of Holocene Warmth and Climate Variability Derived from Icelandic Lake Sediments

该奖项将评估极地放大的作用，并对冰岛全新世的温度进行定量估计。冰岛位于主要海洋和大气环流系统的交界处，在监测北大西洋气候方面具有重要的战略地位。因此，冰岛记录了北大西洋北部大部分地区的状况。该奖项将通过从冰川主导的湖泊中沉积物的物理性质变化中重建冰岛冰盖的状态来解决北极变暖问题。冰帽模型将提供与湖泊沉积物研究得出的冰帽重建结果相一致的过去夏季温度的定量估计。降水的氧同位素比值（δ ta18o）将由北极湖泊沉积物的常见成分摇蚊（蠓）头囊的δ ta18o测定。北极降水的delta18O与年平均气温高度相关，提供了定量的温度重建。Chironomid delta18O提供了北极湖泊过去气温的定量估计，并规避了高纬度地区花粉产量低和植物迁移延迟的持续问题。在相同的沉积物岩心中，与冰岛训练集相关联的摇摇体组合的变化将提供对夏季温度的独立估计。三名美国博士生将参与该项目。此外，两名冰岛研究生和一名博士后将与冰岛合作者一起参与一项同伴研究。Hvitarvatn岩心的电影片段可能会被用于拟议的关于气候变化的公共电视节目中。温盐环流是气候系统中最大的非线性。通过提供全新世温度和冰盖状态的定量数据，本工作将为一般环流模式，特别是那些试图模拟温盐环流的模式提供关键基准。结果将会引起冰岛人的极大兴趣，他们依靠他们的冰盖来发电和作为主要的旅游景点。如果冰岛的冰盖受到预计的全球变暖的威胁，这将对经济产生重大影响。这项研究将有助于限制这些风险。

This award will evaluate the role of polar amplification, and derive quantitative estimates of warmth through the Holocene of Iceland. Iceland occupies a strategic position to monitor North Atlantic climate, as it is situated at the boundary between major oceanic and atmospheric circulation systems. Consequently, Iceland records the status of much of the northern North Atlantic region. This award will address Arctic warmth by reconstructing the status of Iceland's ice caps from changes in the physical properties of sediment accumulating in glacier-dominated lakes. Ice-cap modeling will provide quantitative estimates of past summer warmth consistent with reconstructions of the ice cap derived from the lake sediment study. The oxygen isotopic ratio (delta18O) of precipitation will be determined from the delta18O of chironomid (midge) head capsules, a common constituent of arctic lake sediment. The delta18O of Arctic precipitation is highly correlated with mean annual air temperature, providing quantitative temperature reconstructions. Chironomid delta18O provides quantitative estimates of past air temperatures from Arctic lakes, and circumvents persistent problems with low pollen productivity at high latitudes and with plant immigration delays. Changes in chironomid assemblages in the same sediment cores, tied to an Icelandic training set, will provide an independent estimate of summer temperature.Three U.S. PhD students will be involved in this project. In addition, two Icelandic graduate students and one postdoc will be involved in a companion study with Icelandic collaborators. Film footage of the Hvitarvatn coring may be used in a proposed public television program on climate change. Thermohaline circulation is the greatest non-linearity in the climate system. By providing quantitative data on Holocene warmth and status of ice caps, this work will provide a key benchmark for General Circulation Models, especially those attempting to simulate thermohaline circulation. Results will be of great interest to Icelanders, who depend on their ice caps for hydroelectric power and as major tourist attractions. If Iceland's ice caps are at risk from projected global warming, this will have substantial economic impacts. This research will help constrain those risks.