Collaborative Research: Testing the hypothesis of an orbital forcing of southwestern North America climate over the past 500,000 years

合作研究：检验过去 50 万年北美西南部气候轨道强迫的假设

• 批准号: 1405557
• 负责人: Yemane Asmerom
• 金额: $ 16.15万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-07-01 至 2018-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1405557&HistoricalAwards=false
• 关键词: Collaborative; Research; Testing; hypothesis; orbital

Climate scientists have long documented the strong control of Earth's orbital variations on the waxing and waning of the ice ages. Thirty years ago, an iconic climate record from Devils Hole, Nevada, seemed to suggest that Great Basin the climate of the Great Basin of the western United States was out of step with the orbital rhythm, warming after glacial periods before what would be expected from changes in the Earth's orbit. Now new evidence places Great Basin climate variations back in synchrony with orbital variations, and shows that climate warmed and cooled with the amount of solar radiation reaching the northern Hemisphere during summer over the last 175,000 years. Radiometrically-dated stalagmites from Great Basin caves have the potential extend the record back to 500,000 years before present. These cave deposits record variations in climate in a broad region over and upwind of the cave sites. As such, they are ideally suited to test for an orbital control on Great Basin climate, and will allow comparison to sea surface temperature records in the Pacific Ocean, and to the Devils Hole calcite record. This project will also facilitate long-term climate projections for the southwestern United States based on known future orbital variations. The overarching hypothesis that will be tested in the course of this project is that southwestern paleoclimatic change was paced by Milankovitch (orbital) forcing, through changes in northern hemisphere summer insolation altering atmospheric circulation dynamics over the northeastern Pacific Ocean region. The research team will generate high-resolution oxygen isotope analyses of precisely-dated stalagmites from caves across the Great Basin region, and determine whether or not oxygen isotope variations align with variations in northern hemisphere summer insolation over the past half million years. Oxygen isotopic analyses will be carried out at the University of Nevada Las Vegas, and uranium disequilibrium dating at the University of New Mexico. The research team will include several students from both lead institutions as well as an undergraduate-serving institution, Cornell College (Iowa). The researchers and students will also create cave educational materials for sharing with local caving groups and governmental agencies.

气候科学家长期以来已经记录了对地球轨道变化对冰河时代的上蜡和衰落的强烈控制。 30年前，内华达州魔鬼霍尔（Devils Hole）的标志性气候记录似乎表明，伟大的盆地是美国西部大盆地的气候与轨道节奏不一致，在冰川时期后在冰川时期变暖，然后在地球轨道的变化中预期的是什么。现在，新的证据使巨大的盆地气候变化与轨道变化同步，并表明，在过去的175，000年中，气候随着夏季到达北半球的太阳辐射量而变暖和冷却。来自大盆地洞穴的放射性日期的石塔米特人的潜力将记录延长至现在的500，000年。这些洞穴沉积物记录了洞穴部位的广阔区域中气候变化。因此，它们非常适合测试对巨大盆地气候的轨道控制，并且可以与太平洋的海面温度记录进行比较，并与魔鬼洞有方解石记录进行比较。该项目还将根据已知的未来轨道变化，促进美国西南部的长期气候预测。在这个项目过程中将进行检验的总体假设是，西南古气候变化是通过米兰科维奇（轨道）强迫的节奏，这是通过北半球夏季夏季的无法改变东北太平洋海洋地区大气循环动力学的变化。研究小组将对来自大盆地地区的洞穴的精确石塔木霉菌进行高分辨率氧同位素分析，并确定过去一百万年内氧同位素变化是否与北半球夏季日益降低的变化一致。将在内华达大学拉斯维加斯大学进行氧气同位素分析，并在新墨西哥大学的铀不平衡约会。研究小组将包括来自著名机构的几个学生以及康奈尔大学（IOWA）的本科服务机构。研究人员和学生还将创建洞穴教育材料，以与当地的洞穴团体和政府机构共享。