Collaborative Research: Temperature and atmospheric circulation history of high-latitude Canada across interglacials of the past 1.5 Myr from cave deposits

合作研究：来自洞穴沉积物的过去 1.5 Myr 间冰期加拿大高纬度地区的温度和大气环流历史

• 批准号: 2103100
• 负责人: William McGee
• 金额: $ 30.87万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103100&HistoricalAwards=false
• 关键词: Collaborative; Research; Temperature; atmospheric; circulation

Arctic regions are warming at more than twice the global average, causing rapid melting of permafrost, sea ice and the Greenland ice sheet. These high-latitude changes have pronounced impacts around the globe: permafrost melting releases greenhouse gases, declining sea ice changes wind patterns around the Northern Hemisphere, and loss of ice in Greenland causes sea level rise. As anthropogenic warming continues, it is important to test our understanding of how Arctic climate is likely to change so that we can prepare. This project will reconstruct how Arctic climate has responded during warm periods of last 1.5 million years, using cave deposits from northwestern Canada that archive information about both temperature and precipitation patterns. We will focus particular attention on documenting Arctic climate during periods in the past when permafrost, sea ice and the Greenland ice sheet were all less extensive than today, helping test the potential for unexpected shifts in a world with less ice. The project will contribute to education and outreach by creating videos that will be shared in K-12 classroom visits, convening a teacher workshop to design a teacher training program related to climate change education, and sharing project design and outcomes with First Nations bands in the study area. The project will also involve undergraduate students and train a graduate student.This project will use a unique collection of cave deposits from caves in northwestern Canada to build well-dated records of cave temperature and the oxygen isotope composition of precipitation across interglacials between 400 ka and 1.5 Ma. Cave temperatures will be reconstructed by comparing the oxygen isotope measurements of included fluids to that of the surrounding calcium carbonate, allowing estimates of mean annual temperature changes outside the caves and of the isotopic composition of precipitation. These data will provide some of the only constraints on conditions during mid-Pleistocene interglacials from high-latitude Northern Hemisphere landmasses, enabling testing of hypotheses as to why the Northern Hemisphere cryosphere was much less resilient during interglacials prior to 400 ka. The precipitation isotope reconstructions developed here will offer an essential deeper-time complement to foundational records from the Greenland ice sheet over the last glacial cycle. The study also represents the first application of current-generation fluid inclusion measurements to high-latitude speleothems, potentially opening up similar applications in other high-latitude caves.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

北极地区的变暖是全球平均水平的两倍以上，导致多年冻土，海冰和格陵兰冰盖的快速融化。这些高纬度变化在全球范围内引起了明显的影响：永久冻结熔化释放温室气体，海冰的下降改变了北半球周围的风模式，格陵兰岛的冰损失会导致海平面上升。随着人为变暖的继续，重要的是要测试我们对北极气候如何改变的理解，以便我们可以准备。该项目将重建北极气候在过去150万年的温暖期间如何做出反应，使用加拿大西北部的洞穴沉积物对温度和降水模式进行归档信息。在过去的时期，当多年冻土，海冰和格陵兰冰盖的广泛范围都比今天的时期时，我们将特别关注记录北极气候，这有助于测试一个冰较少的世界中意外转变的潜力。该项目将通过创建将在K-12课堂访问中共享的视频，召集教师研讨会来设计与气候变化教育相关的教师培训计划，并与研究领域的原住民乐队共享项目和成果。该项目还将涉及本科生并培训研究生。该项目将使用来自加拿大西北部洞穴的独特洞穴矿床集合来建立洞穴温度的良好记录，并在400 ka和1.5 mA之间建立跨冰期间沉淀的氧同位素组成。洞穴温度将通过比较随附的液体的氧同位素测量值与周围碳酸钙的氧同位素测量值，从而估计洞穴以外的平均年温度变化和降水的同位素组成。这些数据将为北半球高纬度冰川间冰川中的条件提供一些唯一的限制，这使假设的测试能够测试为什么在400 ka之前的冰期期间，北半球冰冻圈为什么北半球冰圈的弹性要少得多。在上一个冰川周期中，此处开发的沉淀同位素重建将为格陵兰冰盖的基础记录提供更深入的时间补充。这项研究还代表了当前生成流体融合度测量值的首次应用到高纬度斑点上，有可能在其他高纬度洞穴中开放类似的应用。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的审查标准来通过评估来通过评估来支持的。