Collaborative Research: REU: Calibrating the Water Isotope Thermometer in Antarctica Using Abrupt Heinrich Event Signatures in the EDML Ice Core

合作研究：REU：利用 EDML 冰芯中的突变海因里希事件特征校准南极洲的水同位素温度计

• 批准号: 2315927
• 负责人: Jeffrey Severinghaus
• 金额: $ 52.28万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-09-01 至 2026-08-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2315927&HistoricalAwards=false
• 关键词: Collaborative; Research; REU; Calibrating; Water

This project seeks to answer the question, "How cold was Antarctica during the last ice age?" This information will help to predict the magnitude of future warming in Antarctica due to human emissions of heat-trapping gases, with implications for the stability of Antarctic ice sheets and sea level in the next 50 to 100 years. The proposed method uses a new "gas thermometer" based on air trapped in snow and preserved as air bubbles in ice that can be recovered from ice cores. The new thermometer uses ratios of nitrogen and argon isotopes (an isotope of a given element has a different number of neutrons) from the air bubbles in the ice and has been used successfully in Greenland over the past two decades to show that Greenland temperatures during the last ice age were ~35 degrees Fahrenheit colder than at present. Antarctica is more challenging to study than Greenland, but recent improvements in the gas thermometer now make it practical to address Antarctica's temperature history and inform its future under human influence. This project will train graduate and undergraduate students in these methods.The classical method for obtaining past temperatures on polar ice sheets uses the isotopes of water (18O and 2H) and has been shown to suffer from biases, for example underestimating Greenland cooling in the Last Glacial Maximum by a factor of 2. This project seeks to calibrate the water-isotope thermometer in East Antarctica using the recently improved inert-gas thermometer based on isotopes of N2 and Ar. The project will use ice from a core from East Antarctica (Dronning Maud Land) in collaboration with European colleagues. Further, ice samples of the same age from a West Antarctic ice core will be measured as a benchmark. The project will also perform targeted measurements of methane and N2 isotopes along the length of the East Antarctic ice core, to better understand the climate history and firn evolution of the core. These measurements will enable a second, independent calibration of the water-isotope thermometer from the observed gas-age – ice-age difference along the East Antarctic core.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.

该项目旨在回答“上一个冰河时代南极洲有多冷？”这一信息将有助于预测由于人类排放吸热气体而导致南极洲未来变暖的程度，这对南极洲的稳定具有影响。所提出的方法使用一种新的“气体温度计”，该温度计基于雪中的空气并以气泡的形式保存在冰中，可以从冰芯中回收。使用冰中气泡中氮和氩同位素的比率（给定元素的同位素具有不同数量的中子），并在过去二十年中已在格陵兰岛成功使用，以显示上一个冰河时代格陵兰岛的温度南极洲的温度比现在低约 35 华氏度，这比格陵兰岛的研究更具挑战性，但气体温度计的最新改进现在使得了解南极洲的温度历史并提供信息变得切实可行。该项目将培训研究生和本科生使用这些方法。例如，获取极地冰盖过去温度的经典方法使用水的同位素（18O 和 2H），并且已被证明存在偏差。低估了末次盛冰期格陵兰岛的冷却程度，降低了 2 倍。该项目旨在使用最近改进的基于同位素的惰性气体温度计来校准东南极洲的水同位素温度计。 N2 和 Ar. 该项目将与欧洲同事合作使用来自南极洲东部（Dronning Maud Land）的冰芯，此外，还将测量来自西南极洲冰芯的相同年龄的冰样本作为基准。还沿着南极东部冰芯的长度进行甲烷和氮气同位素的有针对性的测量，以更好地了解冰芯的气候历史和冰演化，这些测量将使水同位素的第二次独立校准成为可能。该奖项反映了国家科学基金会的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。