Collaborative Research: Testing the Northern Route for Younger Dryas Meltwater

PI提出了一个为期三年的项目，以调查年轻的仙女座降温的起源。新的证据表明，冰川湖阿加西湖通过麦肯齐河向北极释放了淡水，他们提出，在加拿大群岛西部边缘，应该可以从浮游有孔虫贝壳中的氧同位素比率中检测到这一信号。该项目包括一项为期三周的探险，以调查海底和次海底，并收集东部波弗特海的沉积物岩心，该地区偏远，尚未得到很好的勘探。除了作为生成反映海面盐度的同位素数据的一部分的沉积物处理和微古生物学外，还提出了两个互为补充的岸基项目。首先是将大陆边缘的新地球物理数据与公海的气候历史、沉积物输送、相对海平面变化和陆地气候结合起来，就像以前对楚科奇海所做的那样。第二种是将地球化学数据与高分辨率大气环流模型的结果进行比较，该模型被配置为揭示熔融水的路径和混合。尽管古海洋数据将在空间上受到限制，但模型运行将显示北极和北欧海域的低盐度分布，在那里，淡水可能影响了深海倾覆，并导致年轻的仙女木冷却。年轻的仙女木是大约13,000年前开始的气候降温时期，持续了1000多年。它扭转了气候变暖的一段时期，尽管日照强度继续增加。这项研究将试图确定使气温趋势发生这种逆转的机制，从而为讨论未来是否可能发生类似的变化提供信息。

The PIs propose a three-year project to investigate the origin of the Younger Dryas cooling. New evidence suggests that glacial Lake Agassiz released fresh water to the Arctic through the Mackenzie River and they propose that this signal should be detectable along the western margin of the Canadian Archipelago in the oxygen isotope ratio in the shells of planktonic foraminifera. The project involves a three-week expedition to survey the seafloor and subbottom layers and collect sediment cores from the eastern Beaufort Sea, a region that is remote and has not been well explored. Besides the sediment processing and micropaleontology that are part of generating the isotope data that reflect sea surface salinity, two complementary shore-based projects are proposed. The first is to integrate the new geophysical data on the continental margin with the climate history of the open sea, sediment transport, relative sea level change, and terrestrial climate, as they have done previously for the Chukchi Sea. The second is to compare the geochemical data with results from a high resolution General Circulation Model that is configured to reveal the path and the mixing of the melt water. Although the paleoceanographic data will be spatially limited, model runs will show the low salinity distribution in the Arctic as well as in the Nordic seas where the freshening may have affected deep ocean overturning and caused the Younger Dryas cooling.The Younger Dryas was a period of climatic cooling that began about 13,000 years ago and lasted more than 1000 year. It reversed a period of climatic warming, even though insolation continued to increase. This study will attempt to determine the mechanism that allowed such a reversal in temperature trend to occur and, thus, inform discussions of whether similar changes are probable in the future.