Collaborative Research: High latitude temperature and biological responses to Plio-Pleistocene global change

赫伯特和劳伦斯建议摘要0623487这个项目旨在提高我们的理解如何在两个半球的高纬度海洋的条件变化的过程中，地球的最后一个主要的气候革命从200万至400万年前（Ma）。 在这一时期，北方冰川化，大幅度的气候循环开始，并持续到现在。 研究所提议，从北半球和南半球的一些深海地点重建过去海洋表面温度和生物活动的时间序列（平均采样分辨率为3 ka），这些地点在200万至400万年的时间间隔内有连续的沉积物覆盖。 对烯酮生物分子的最新有机地球化学分析将与对底栖有孔虫的稳定同位素测量一起使用，以提供样品的准确年代测定。 该项目将检验以下假设：1）高纬度地区的温度变化从4到3 Ma大幅增加，冰川作用是一个晚期反应（而不是主要驱动因素）导致气候系统的早期变化;（2）高纬海洋冷却在南北半球基本对称，这表明温室气体水平的下降在北方半球冰川作用的开始中起了主要作用，3）两个半球的生物生产力几乎同时发生了变化，这表明高纬度地区的行星风场发生了重大变化，随着北方冰河期的加剧，海洋碳“泵”也发生了重大重组。该项目的更广泛影响将包括教育/外联活动和向古气候/气候学界传播一套庞大而独特的数据。 该项目将支持本科生的参与，并将有助于研究生和博士后的培训和发展。 研究数据将公布在NGDC古气候网站上。

Herbert and Lawrence Proposal Abstract 0623487This project seeks to improve our understanding of how conditions in the high latitude oceans of both hemispheres changed over the course of the Earth's last major climate revolution from 2-4 million years ago (Ma). During this period, the northern hemisphere became glaciated, and large amplitude climate cycles began that continue to the present. The PI's propose to reconstruct time series (average sampling resolution of 3 ka) of past ocean surface temperature and biological activity from a number of deep sea sites in the N and S hemispheres with continuous sediment coverage across the 2-4 Myr time interval. State-of-the-art organic geochemical analyses of alkenone biomolecules will be utilized together with stable isotope measurements on benthic foraminifera to provide accurate dating of the samples. This project will test hypotheses that 1) temperature variability at the high latitudes grew substantially from 4 to 3 Ma and that glaciation was a late response (rather than a primary driver) to earlier shifts in the climate system; 2) the pattern of high latitude ocean cooling was more or less symmetrical in the two hemispheres, suggesting that declining greenhouse gas levels played a major role in the onset of northern hemisphere glaciation and 3) biological productivity shifted at approximately the same time in both hemispheres, indicating a major change in the planetary wind fields at high latitudes, and a major reorganization of the ocean carbon "pump" as northern hemisphere ice ages intensified.Broader impacts of the project will include educational/outreach activities and the dissemination of a large and unique data set to the paleoclimatic/climatology community. This project will support undergraduate participation and will contribute to graduate and post-doctoral training and development. Research data will be posted on the NGDC Paleoclimate web site.