Developing a High-Resolution Sea-Level Record to Measure the Magnitude and Timing of the Catastrophic 8.2 ka Freshwater Release - Implications for North Atlantic Climate Dynamics

开发高分辨率海平面记录来测量灾难性 8.2 ka 淡水泄漏的强度和时间 - 对北大西洋气候动态的影响

• 批准号: 0601814
• 负责人: Torbjorn Tornqvist
• 金额: --
• 依托单位: Tulane University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0601814&HistoricalAwards=false
• 关键词: Developing; Resolution; Sea; Level; Record

Developing a High-Resolution Sea-Level Record to Measure the Magnitude and Timing of the Catastrophic 8.2 ka Freshwater Release - Implications for North Atlantic Climate DynamicsAn abrupt, century-scale cooling ~8200 years ago, known as the "8.2 ka event," is believed to have been caused by the catastrophic release of freshwater from a giant ice-dammed lake (Lake Agassiz) into the North Atlantic Ocean. However, a comprehensive understanding of this prominent climate change is hampered by uncertainty about the magnitude, nature, and timing of this meltwater pulse. Current estimates of the freshwater volume associated with the 8.2 ka event correspond to an equivalent sea-level rise of ~0.3 to ~1.4 m. In the Mississippi Delta region, basal peat (brackish water derived) encroaches on a consolidated Pleistocene basement and the microtidal regime in the Gulf of Mexico enables the reconstruction of sea-level change with exceptionally high resolution. In this project, the PI's will 14C date basal-peat samples that track sea-level change during this critical time interval. Sampling resolution will be on the order of 10 cm. Stable carbon isotope data will provide data to estimate the salinity of the peat-forming ecosystem so as to establish the relationship with sea level. The combined data will be used to estimate the total amount of sea-level rise as well as determining the timing of this event. These data will also permit the PI's to provide an estimate of the amount of freshwater delivered directly by the Laurentide Ice Sheet, as well as providing input data to explore the climatic effects of different mechanisms and locations of freshwater release using a coupled ocean-atmosphere model. These results will provide new insights about the sensitivity of ocean circulation to various scenarios of freshwater forcing, which could help to better understand the consequences of continued freshening of the North Atlantic Ocean in the greenhouse world. The project will provide training for one PhD student, as well as four undergraduate field assistants.

开发高分辨率海平面记录来测量灾难性的8.2 ka淡水释放的幅度和时间-对北大西洋气候动力学的影响大约8200年前，一个突然的，世纪规模的冷却，被称为“8.2 ka事件”，被认为是由一个巨大的冰坝湖（阿加西湖）的淡水灾难性释放到北大西洋造成的。然而，对这种突出的气候变化的全面了解受到这种融水脉冲的大小，性质和时间的不确定性的阻碍。与8.2 ka事件相关的淡水量的当前估计对应于约0.3至约1.4 m的等效海平面上升。在密西西比三角洲地区，基底泥炭（咸水衍生）侵犯了巩固的更新世基底和在墨西哥湾的微潮制度，使重建海平面变化具有非常高的分辨率。在这个项目中，PI的将14 C日期的基泥炭样本，跟踪海平面变化在这一关键的时间间隔。采样分辨率将为10 cm量级。稳定碳同位素数据将为估算泥炭形成生态系统的盐度提供数据，从而建立与海平面的关系。综合数据将用于估计海平面上升的总量以及确定这一事件的时间。这些数据还将允许PI提供直接由Laurentide冰盖提供的淡水量的估计，以及使用耦合的海洋-大气模型提供输入数据，以探索淡水释放的不同机制和位置的气候影响。这些结果将提供有关海洋环流对各种淡水强迫情景的敏感性的新见解，这可能有助于更好地了解北大西洋在温室世界中持续淡化的后果。该项目将为一名博士生和四名本科生实地助理提供培训。