Collaborative Research: High Latitude Temperature and Biological Responses to Plio-Pleistocene Global Change

赫伯特和劳伦斯的建议摘要这个项目试图提高我们对地球上一次重大气候革命期间，即200万-400万年前(Ma)期间，两个半球的高纬度海洋的状况如何变化的理解。在此期间，北半球变得冰化，开始了大规模的气候循环，并一直持续到现在。国际海洋研究所建议从北半球和S半球的一些深海站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3ka)，这些站点在2-4 Myr时间间隔内具有连续的沉积物覆盖。将利用对烯酮生物分子进行的最先进的有机地球化学分析以及对海底有孔虫的稳定同位素测量来提供准确的样品测年。这个项目将检验这样的假设：1)高纬度地区的温度变率从4 Ma大幅增长到3 Ma，冰川作用是对气候系统早期变化的晚期反应(而不是主要驱动因素)；2)高纬度海洋冷却的模式在两个半球或多或少是对称的，这表明温室气体水平的下降在北半球冰川的开始中发挥了主要作用，3)生物生产力在两个半球几乎同时发生转移，表明高纬度行星风场发生了重大变化，随着北半球冰龄的加剧，海洋碳“泵”的重大重组。该项目的广泛影响将包括教育/推广活动和向古气候/气候学社区传播大型和独特的数据集。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。研究数据将在NGDC古气候网站上公布。

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.