Putting the West Antarctic Ice Sheet into context

1042728/Denton该奖项支持一个项目，旨在对南美洲和南极洲末次冰期终止期间事件的原因和模式进行新的见解。 一种新的观点认为，南大洋（SO）变暖是由北方半球（NH）开始的一系列事件驱动的，并与最后一次终止的半球间气候跷跷板有关，是驱使西南极冰盖（WAIS）从晚冰期最大期（LGM）位置回到现在的接地线的潜在机制。这种海洋热强迫会通过加速边缘漂浮冰架和冰舌的基础融化速率来影响WAIS。这样一个命题的有效性，可以检查在各种中高纬度地区的冰退缩的详细年表。根据这样的年表，可以确定冰消退的间隔是否形成与已知在终止期间在SO中发生的变暖脉冲的定时相匹配的模式。 该项目的智力价值在于，它将测试这样一个命题，即由NH Stadial驱动的SO中的变暖脉冲是导致WAIS衰退到其现今配置的关键事件，从而建立了不可逆转的崩溃的可能性。这个测试是基于放置到一个全球范围内的时间和结构的冰川衰退沿着一个样带从最南端的安第斯山脉的罗斯湾。该项目将通过建立南美洲最南端和北方南极半岛末次冰期后冰衰退的年表来研究样带的中部。是因为与冰川沉积物有关的大量可确定年代的陆地有机物质吗？最快的进展将从南美洲最南端开始。具体而言，核心将收集从众多沼泽之间的末次盛冰期的限制和现今的冰在科迪勒拉达尔文和Hoste岛，并使用14 C日期的基础有机残留物，以制定一个年表的冰衰退。 这项工作的更广泛影响包括致力于教育和外联。 这项工作将教育一名研究生，并从这笔赠款的材料将用于大学课程，以及在介绍给小学和中学和高级社区。这项提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.