Collaborative Research: Testing the Northern Route for Younger Dryas Meltwater

PI提出了一个为期三年的项目，以调查新仙女木冷却的起源。新的证据表明，冰川湖阿加西斯释放淡水通过麦肯齐河到北极，他们提出，这一信号应该是检测沿着加拿大群岛的西部边缘的氧同位素比在壳的南极有孔虫。该项目包括一个为期三周的考察，调查海底和海底下层，并收集博福特海东部的沉积物岩心，该地区地处偏远，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体古生物学之外，还提出了两个互补的岸上项目。第一个是将大陆边缘的新地球物理数据与公海的气候历史、沉积物搬运、相对海平面变化和陆地气候相结合，就像以前对楚科奇海所做的那样。第二个是比较地球化学数据与高分辨率大气环流模型的结果，该模型被配置为揭示融水的路径和混合。虽然古海洋学数据在空间上是有限的，但模型运行将显示北极和北欧海域的低盐度分布，在这些海域，淡水化可能影响了深海翻转，并导致了新仙女木期的冷却。新仙女木期是一个气候冷却时期，始于大约13,000年前，持续了1000多年。 它扭转了气候变暖的时期，尽管日照继续增加。 这项研究将试图确定允许温度趋势发生这种逆转的机制，从而为未来是否可能发生类似变化的讨论提供信息。

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.