Seasonality, Summer Cooling, and Calibrating the Approach of the Icehouse in Late Eocene Antarctica

为了了解未来几代人的环境条件可能会是什么样子，我们需要求助于过去世界确实更温暖的时代的档案，在任何人将它们纳入集体记忆之前。地球过去的地质记录让我们得以一窥未来可能发生的事情。伊瓦尼和她的团队在过去全球变暖的时期对南极洲进行了研究，以了解沿海地区的温度和降雨的季节性在未来可能会如何变化。他们将利用化石的化学成分（这些变量的自然档案）来检验一个具有挑衅性的假设，即当海洋变暖时，高纬度地区会出现接近季风的情况。如果这是真的，我们可以预期高纬度航线将变得更加危险，适应持续低温的脆弱海洋生态系统将受到影响。随着有关人类活动未来可能如何影响地球的信息越来越多，我们将能够在今天做出更明智的政策决定。这项研究涉及一个国际学者团队，其中包括几位女科学家，培训研究生，以及一个公共博物馆展览，教育孩子们我们如何研究地球的古代气候，以及我们可以从中学到什么。南极洲是了解地球如何？美国的气候系统在二氧化碳升高的条件下工作。两极是地球上对气候变化最敏感的区域，赤道到两极的温度梯度和高纬度变暖的放大程度是气候模式要捕捉的重要组成部分。因此，具有良好年龄控制的准确代理数据对于测试数值模型和建立全球模式至关重要。西摩岛的拉梅塞塔组是唯一记录在案的始新世全球变暖时期的海洋剖面，暴露在大陆的露头上；因此，它的气候记录是研究变暖不可或缺的一部分。早期数据表明，沿海地区可能出现强烈的季节性降水和径流。古生物学家、地球化学家和气候建模者之间的合作将利用来自浅海双壳类化石的季节分辨del-18O数据来验证这一点，并结合夏季降水（叶蜡del-D）和当地海水（块状同位素）组成的独立代用物，跟踪整个剖面的季节性演变。预计的盐度分层对区域气候的影响将在数值气候模式模拟的背景下进行评估。除了更清楚地了解这段高二氧化碳时期的高纬度条件外，代理和模型结果的结合将提供关于始新世温暖如何维持以及随后的冷却如何发生的见解。此外，87Sr/86Sr壳碳酸盐分析的新方法将使年龄控制更加精细，从而使这一重要剖面与其他地区的对比能够澄清全球气候梯度。这里概述的项目将从现有的样本中开发新的和详细的古气候记录，使用经过调整的和更新的代用物，以新颖的方式在这里应用。季节性极端值是大多数研究通常无法获得的气候参数，但对了解气候变化至关重要；这些可能在这个保存完好的增生-大型化石剖面中得到解决。这是一项综合研究，将地球上一个关键地区的海洋和陆地气候记录联系起来，跨越了新生代最重要的气候转变。

In order to understand what environmental conditions might look like for future generations, we need to turn to archives of past times when the world was indeed warmer, before anyone was around to commit them to collective memory. The geologic record of Earth's past offers a glimpse of what could be in store for the future. Research by Ivany and her team looks to Antarctica during a time of past global warmth to see how seasonality of temperature and rainfall in coastal settings are likely to change in the future. They will use the chemistry of fossils (a natural archive of these variables) to test a provocative hypothesis about near-monsoonal conditions in the high latitudes when the oceans are warm. If true, we can expect high-latitude shipping lanes to become more hazardous and fragile marine ecosystems adapted to constant cold temperatures to suffer. With growing information about how human activities are likely to affect the planet in the future, we will be able to make more informed decisions about policies today. This research involves an international team of scholars, including several women scientists, training of graduate students, and a public museum exhibit to educate children about how we study Earth's ancient climate and what we can learn from it.Antarctica is key to an understanding how Earth?s climate system works under conditions of elevated CO2. The poles are the most sensitive regions on the planet to climate change, and the equator-to-pole temperature gradient and the degree to which high-latitude warming is amplified are important components for climate models to capture. Accurate proxy data with good age control are therefore critical for testing numerical models and establishing global patterns. The La Meseta Formation on Seymour Island is the only documented marine section from the globally warm Eocene Epoch exposed in outcrop on the continent; hence its climate record is integral to studies of warming. Early data suggest the potential for strongly seasonal precipitation and runoff in coastal settings. This collaboration among paleontologists, geochemists, and climate modelers will test this using seasonally resolved del-18O data from fossil shallow marine bivalves to track the evolution of seasonality through the section, in combination with independent proxies for the composition of summer precipitation (leaf wax del-D) and local seawater (clumped isotopes). The impact of the anticipated salinity stratification on regional climate will be evaluated in the context of numerical climate model simulations. In addition to providing greater clarity on high-latitude conditions during this time of high CO2, the combination of proxy and model results will provide insights about how Eocene warmth may have been maintained and how subsequent cooling came about. As well, a new approach to the analysis of shell carbonates for 87Sr/86Sr will allow refinements in age control so as to allow correlation of this important section with other regions to clarify global climate gradients. The project outlined here will develop new and detailed paleoclimate records from existing samples using well-tuned as well as newer proxies applied here in novel ways. Seasonal extremes are climate parameters generally inaccessible to most studies but critical to an understanding of climate change; these are possible to resolve in this well-preserved, accretionary-macrofossil-bearing section. This is an integrated study that links marine and terrestrial climate records for a key region of the planet across the most significant climate transition in the Cenozoic.