Collaborative Research: Testing the Orbital Theory of Ice Ages Through Analysis of Glacial Deposits and Numerical Modeling

这项研究项目将研究南半球冰河时代的时间和原因，以及这些观测到的气候变化与北方半球的气候变化相比如何。 地球系统科学中的一个主要问题是确定是什么驱使地球的不同部分在冰河时代的气候中切换。 这是一个悬而未决的问题。传统的米兰科维奇或轨道“冰河时代理论”认为，夏季北方半球的日照强度决定了地球上冰河时代的到来。 然而，在北方和南半球对夏季日照强度的测量发现是不同步的。 如果地球周围的冰川同时以类似的方式扩张和退缩，那么必须涉及其他驱动机制，例如温室气体或覆盖北方陆地的最大冰盖的全球影响。 一个问题是，在南半球，关于最后一次冷冰期何时开始、持续多久以及何时结束的信息不足。 如果没有这些信息，科学家们就无法评估南半球冰川气候与可能的驱动力的对应程度，例如（轨道）太阳日射强度的变化，北方冰盖和大气二氧化碳。 他们也无法评估冰河时代气候的根本原因，也无法完善米兰科维奇的理论。 该项目将侧重于收集和分析有助于记录南美洲南部冰川如何随时间变化的材料。 研究人员将采用最先进的技术来测定冰川地貌和冰川气候建模。冰川的过时古地理将为使用研究人员和其他人开发的模型进行的实验提供边界条件，以评估与可能的气候参数相关的作用和响应，例如温度和降水量范围，这些范围是安第斯山脉南部冰盖生长和退缩所需的。该项目将加深对冰河时代气候的性质和原因以及相关自然环境的了解。全球化进程及其在地球仪上的时空差异。 该项目还将提供有关自然气候状态的增强信息，例如最后一个冰河时期的气候，可用作模拟未来变化的大气环流模型的试验台。 该项目将为加强美国和智利科学家之间的国际研究合作提供机会。 将为本科生提供教育和培训机会，并将通过与美国自然历史博物馆和纽约市学校的合作关系开展教育推广活动。

This research project will examine the timing and causes of ice ages in the Southern Hemisphere and how these observed climate changes compare with those found in the Northern Hemisphere. A major question in the earth-system sciences has been ascertaining what drives different sections of Earth to switch in and out of ice age climates. This is an outstanding question that remains unresolved. The traditional Milankovitch or orbital "ice-age theory" proposes that the intensity of summer insolation received in the Northern Hemisphere paces ice ages across Earth. Measurements of the intensity of summer insolation in the Northern and Southern hemispheres have been found to be out of phase, however. If glaciers expand and retreat in similar ways around Earth at the same time, other driving mechanisms therefore must be involved, such as greenhouse gasses or a global impact of the largest ice sheets that covered the land in the Northern Hemisphere. A problem is that in the Southern Hemisphere, there is insufficient information regarding when the last cold glacial period started, how long it lasted, and when it ended. Without this information, scientists are ill-equipped to assess how well Southern Hemisphere glacial climates correspond to possible driving forces, such as changes in (orbital) solar insolation intensity, Northern Hemisphere ice sheets, and atmospheric carbon dioxide. They also are unable to assess the underlying causes of ice-age climates and to refine the Milankovitch theory. This project will focus on the collection and analyses of materials that help document how glaciers in southern South America have changed over time. The investigators will employ state-of-the-art techniques in dating glacier landforms and glacial-climate modeling. The dated paleogeography of glaciers will provide boundary conditions for experiments using models developed by the researchers and others to assess the roles and responses associated with possible climate parameters, such as temperature and precipitation ranges that are needed for an ice sheet to grow and retreat over the southern Andes.This project will provide deeper understanding of the nature and causes of ice age climates and related natural environmental processes as well as their spatial and temporal differences around the globe. The project also will provide enhanced information about natural climate states, such as the climate during the last ice age that can be used as test beds for general circulation models that simulate future change. The project will provide opportunities to enhance international research collaborations between scientists in the U.S. and Chile. Education and training opportunities will be provided for undergraduate students, and educational outreach will be pursued through collaborative relationships with the American Museum of Natural History and New York City schools.