In this talk I will present direct observations of carbon dioxide (CO2) concentrations in ice cores drilled in Allan Hills Blue Ice Areas, East Antarctica. Based on the isotopic composition of argon in the trapped air, ice as old as 2 million years (Ma) was identified, with a single unreplicated sample dating back to 2.7±0.3 Ma. The oldest pristine CO2 samples date back to 1.5 Ma and range between 217 to 256 ppm. The similarity between the Early- and Late-Pleistocene interglacial CO2 argues against the notion that a long-term decline in atmospheric CO2 initiated the 100 kyr glacial cycles. Older CO2 samples are affected by the in situ production of CO2 due to respiration. Additionally, Allan Hills blue ice provides a prime record of atmospheric oxygen. Our results show a surprising lack of variability from 1.5 to 0.95 Ma; even during the past ~0.9 Ma, when the rate of decline was very slow.
颜余真，美国莱斯大学地球科学系博士后。2019年博士毕业于普林斯顿大学地球科学系（导师Michael Bender/John Higgins）。研究方向为古气候和同位素地球化学，主要手段为冰芯包裹气体的元素和同位素组成分析。于2014-15年参与了东南极地区Allan Hills蓝冰区为期十周的科学考察，所发现的270万年冰芯入选《科学》杂志2017年十大科学突破之一。
Conference ID (For ZOOM)：1855016889
Suihui (随会) link: https://private.suimeeting.com/share/j/1855016889