P2C2: Insolation Control on Ice Sheet Mass Balance in the 41-Kyr World: A Test of Multiple Hypotheses

提供的资金用于调查上新世晚期和更新世早期41，000年冰川周期的物理机制。 这项研究的前提是，这一时期的冰川循环对于现有的气候理论来说是一个谜。 标准米兰科维奇模型的实际应用预测，北方半球（NH）冰量应随NH夏季日射量线性和一致地变化（即，6月65°N）在岁差（41，000年）和岁差（21，000年）周期。然而，数据表明，岁差频率仅在上新世晚期冰量记录的一小部分中勉强可辨别。同样，大多数用于研究上新世晚期和更新世早期气候历史的计算机模型也预测了模拟冰量中的强烈岁差信号。研究人员提出了这样的问题：“数值气候模型是否缺少了气候或冰盖物理学的一些基本部分？或者是我们对冰量代理的假设有缺陷？“具体来说，研究人员将评估墨西哥湾密西西比流域融水流出的信号，以测试两个相互竞争的假设，以解释41,000年米兰科维奇循环世界的难题。第一个假设是综合日照假设的Huybers，预测的时间消融/融水事件的南部边缘的Laurentide冰盖应起搏的温度。 另一种是Raymo的反相位进动冰假说，该假说预测劳伦特消融/融水事件应强烈地受到进动的影响。更广泛的影响涉及强大的教育指导部分和同样强大的智力部分，这可能有助于在理解冰盖和海平面动态方面取得变革性进展。

Funding is provided to investigate physical mechanisms responsible for the 41,000 year glacial cycles of the Late Pliocene and Early Pleistocene. The premise of the research is that the glacial cycles of this time are an enigma with respect to existing theories of climate. The de facto application of the standard Milankovitch model predicts that Northern Hemisphere (NH) ice volume should vary linearly and coherently with NH summer insolation (i.e., June 65°N) at the obliquity (41,000 year) and precession (21,000 year) cycles. Yet, the data indicates that the precession frequency is only barely discernable in a small section of Late Pliocene ice volume records. Similarly, most computer models that have been used to study the climate history of the Late Pliocene and Early Pleistocene interval also predict a strong precession signal in the modeled ice volume. The researcher poses the questions; "Are numerical climate models missing some fundamental piece of climate or ice sheet physics? Or is it our assumptions about ice volume proxies that are flawed?"Specifically, the researcher will evaluate the signal of meltwater outflow from the Mississippi Drainage Basin in the Gulf of Mexico to test two competing hypotheses to explain the conundrum of the 41,000 year Milankovitch cycle world. The first hypothesis is the integrated insolation hypothesis of Huybers that predicts the timing of ablation/meltwater events on the southern margin of the Laurentide ice sheet should be paced by obliquity. The other is the anti-phase precession ice hypothesis of Raymo which predicts that Laurentide ablation/meltwater events should be paced strongly by precession. The broader impacts involve a strong educational mentoring portion and an equally strong intellectual portion that may help lead to transformative advances in understanding ice sheet and sea level dynamics.