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

这个项目试图回答这个问题，“在上一个冰河时代，南极洲有多冷？”这些信息将有助于预测由于人类排放的吸热气体而导致的南极洲未来变暖的幅度，并对未来50至100年内南极冰盖和海平面的稳定性产生影响。提出的方法使用了一种新的“气体温度计”，这种温度计基于积雪中的空气，并保存为冰中的气泡，可以从冰芯中回收。新的温度计使用了冰中气泡中的氮和氩同位素(一种给定元素的同位素具有不同数量的中子)的比率，并在过去20年中在格陵兰成功地使用，表明上一次冰河时代格陵兰的温度比现在低约35华氏度。南极洲的研究比格陵兰岛更具挑战性，但最近气体温度计的改进使研究南极洲的温度历史并在人类影响下预测其未来成为现实。该项目将培训研究生和本科生使用这些方法。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)，并已被证明存在偏差，例如，将格陵兰在最后一次冰盛期的降温低估了2倍。该项目试图使用最近改进的基于氮和Ar同位素的惰性气体温度计来校准南极洲东部的水同位素温度计。该项目将与欧洲同事合作，使用来自南极洲东部(Dronning Maud Land)岩心的冰。此外，来自西南极冰芯的相同年龄的冰样将作为基准进行测量。该项目还将对沿东南极冰芯长度的甲烷和氮同位素进行有针对性的测量，以更好地了解冰芯的气候历史和积雪演化。这些测量将使水同位素温度计能够根据观测到的南极东部岩芯的气体年龄-冰期差异进行第二次独立校准。这一裁决反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.