Putting the West Antarctic Ice Sheet into context

1042728/ denton该奖项支持一个项目，该项目旨在对南美洲和南极洲最后一次冰川终止期间事件的原因和模式进行新的见解。一种新出现的观点认为，在北半球（NH）开始的一系列事件的驱动下，南大洋（SO）变暖，并与最后一次终止的半球间气候跷跷板有关，这是推动南极西部冰盖（WAIS）从晚期冰川极大期（LGM）位置回到现在的基准线的潜在机制。这种海洋热强迫会通过加速边缘浮冰架和冰舌的基底融化速率来影响WAIS。这一命题的有效性可以从各种中高纬度地点的冰退缩的详细年表中加以检验。从这样的年表中，可以确定冰消退的间隔是否形成了一种模式，这种模式是否与已知在终止期间在SO中发生的变暖脉冲的时间相吻合。这个项目的智力价值在于，它将检验这样一个命题，即由NH运动驱动的SO变暖脉冲是导致WAIS衰退到目前状态的关键事件，并为不可逆转的崩溃创造了可能性。这个测试是基于将冰川衰退的时间和结构置于全球背景下，沿着从最南端的安第斯山脉到罗斯海湾的样带。该项目将通过在南美洲最南端和南极半岛北部建立LGM之后的冰消退年表来检查样带的中部。因为与冰川沉积物有关的丰富的陆生有机物？最快的进展将从南美洲最南端开始。具体来说，将从位于LGM极限和达尔文科迪勒拉（Cordillera Darwin）和霍斯特岛（Isla Hoste）的现代冰层之间的众多沼泽中收集岩芯，并使用基底有机遗骸的14C日期来制定冰层消退的年表。这项工作的更广泛影响包括对教育和外联的承诺。这项工作将教育一名研究生，这笔资助的材料将用于大学课程，以及在小学、中学和老年社区的演讲。这项建议不需要在南极进行实地工作。

1042728/DentonThis award supports a project to develop new insights into the cause and pattern of events during the last glacial termination in South America and Antarctica. One emerging view is that a warming Southern Ocean (SO), driven by a chain of events initiated in the Northern Hemisphere (NH) and tied to the interhemispheric climate seesaw of the last termination, was the underlying mechanism that drove the West Antarctic ice sheet (WAIS) from its Late Glacial Maximum (LGM) position back to present-day grounding lines. This ocean thermal forcing would have impacted WAIS by accelerating basal melt rates on fringing floating ice shelves and tongues. The validity of such a proposition can be examined from detailed chronologies of ice retreat at a variety of middle to high latitude sites. From such chronologies, it can be determined whether or not the intervals of ice recession form a pattern that fits the timing of warming pulses known to have occurred in the SO during the termination. The intellectual merit of this project is that it will test the proposition that warming pulses in the SO, driven by NH stadials, are the key events that culminated in recession of WAIS to its present-day configuration, setting up the possibility of irreversible collapse. This test is based on placing into a global context the timing and structure of glacial recession along a transect from the southernmost Andes to the Ross Embayment. This project will examine the middle of the transect, by establishing the chronology of ice recession following the LGM in southernmost South America and on the northern Antarctic Peninsula. Because of the abundance of datable terrestrial organic material in association with glacial deposits ?the most rapid progress will be made by starting in southernmost South America. Specifically, cores will be collected from numerous bogs located between the LGM limit and present-day ice in Cordillera Darwin and on Isla Hoste, and use 14C dates of basal organic remains to develop a chronology for ice recession. The broader impacts of this work include a commitment to education and outreach. This work will educate a graduate student and material from this grant will be used in college courses, as well as in presentations to elementary and middle schools and to senior communities. This proposal does not require field work in the Antarctic.