USAP-DC

Bubbles of ancient air trapped in ice cores permit the direct reconstruction of atmospheric composition and allow us to link greenhouse gases and global climate over the last 800,000 years. Previous field expeditions to the Allan Hills blue ice area, Antarctica, have recovered ice cores that date to one million years, the oldest ice cores yet recovered from Antarctica. These records have revealed that interglacial CO2 concentrations decreased by 800,000 years ago and that, in the warmer world 1 million years ago, CO2 and Antarctic temperature were linked as during the last 800,000 years. This project will return to the Allan Hills blue ice area to recover additional ice cores that date to 1 million years or older. The climate records developed from the drilled ice cores will provide new insights into the chemical composition of the atmosphere and Antarctic climate during times of comparable or even greater warmth than the present day. Our results will help answer questions about issues associated with anthropogenic change. These include the relationship between temperature change and the mass balance of Antarctic ice; precipitation and aridity variations associated with radiatively forced climate change; and the climate significance of sea ice extent. The project will entrain two graduate students and a postdoctoral scholar, and will conduct outreach including workshops to engage teachers in carbon science and ice cores.

Between about 2.8-0.9 million years ago, Earth's climate was characterized by 40,000-year cycles, driven or paced by changes in the tilt of Earth's spin axis. Much is known about the "40,000-year" world from studies of deep-sea sediments, but our understanding of climate change during this period is incomplete because we lack records of Antarctic climate and direct records of atmospheric greenhouse gas concentrations. We propose to address these issues by building on our recent studies of ancient ice from the Main Ice Field, Allan Hills, Antarctica. During previous field seasons we recovered ice extending, discontinuously, from 0.1-1.0 million years old. Ice was dated by measuring the 40Ar/38Ar (Argon) ratio of the trapped gases. Our discovery of million year-old ice demonstrates that there is gas-record-quality ice from the 40,000-year world in the Allan Hills Main Ice Field. We have identified two different sites, each overlying bedrock at ~ 200 m depth, that are attractive targets for coring ice dating to 1 million years and older. This project aims to core the ice at these two sites, re-occupy a previous site with million year-old ice and drill it down to the bedrock, and generate 10-20 short (~10-meter) cores in areas where our previous work and terrestrial meteorite ages suggest ancient surface ice. We plan to date the ice using the 40Ar/38Ar ages of trapped Argon. We also plan to characterize the continuity of our cores by measuring the deuterium and oxygen isotope ratios in the ice, methane, ratios of Oxygen and Argon to Nitrogen in trapped gas, the Nitrogen-15 isotope (d15N) of Nitrogen, and the Oxygen-18 isotope (d18O) of Oxygen. As the ice may be stratigraphically disturbed, these measurements will provide diagnostic properties for assessing the continuity of the ice-core records. Successful retrieval of ice older than one million years will provide the opportunity for follow-up work to measure the CO2 concentration and other properties within the ice to inform on the temperature history of the Allan Hills region, dust sources and source-area aridity, moisture sources, densification conditions, global average ocean temperature, and greenhouse gas concentrations. We will analyze the data in the context of leading hypotheses of the 40,000-year world and the Mid-Pleistocene Transition to the 100,000-year world. We expect to advance understanding of climate dynamics during these periods.

Person	Role
Mayewski, Paul A.	Investigator
Kurbatov, Andrei V.	Co-Investigator
Higgins, John	Investigator
Bender, Michael	Co-Investigator

Antarctic Glaciology	Award # 1443306
Antarctic Glaciology	Award # 1443263

USAP-1443306_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Stable water isotope data for the AH-1503 ice core drilled at the Allan Hills Blue ice area	CSV	exist
USAP-DC	Stable water isotope data for the AH-1502 ice core drilled at the Allan Hills Blue ice area	CSV	exist
USAP-DC	Stable water isotope data for the surface samples collected at the Allan Hills Blue ice area	CSV	exist
USAP-DC	Elemental and isotopic composition of heavy noble gases in Allan Hills ice cores	CSV	exists
USAP-DC	Carbon dioxide concentration and its stable carbon isotope composition in Allan Hills ice cores	CSV	exists
USAP-DC	Methane concentration in Allan Hills ice cores	CSV	exists
USAP-DC	Elemental and isotopic composition of nitrogen, oxygen, and argon in Allan Hills ice cores	CSV	deprecated
USAP-DC	Stable isotope composition of the trapped air in the Allan Hills S27 ice core	CSV	deprecated
USAP-DC	Greenhouse gas composition in the Allan Hills S27 ice core	CSV	exists
USAP-DC	Elemental and isotopic composition of nitrogen, oxygen, and argon in Allan Hills ice cores	CSV	exists
USAP-DC	Stable isotope composition of the trapped air in the Allan Hills S27 ice core	CSV	exists

1. Higgins, J.A., Kurbatov, A.V., Spaulding, N.E., Brook, E., Introne, D.S., Chimiak, L.M., Yan, Y., Mayewski, P.A. and Bender, M.L., 2015. Atmospheric composition 1 million years ago from blue ice in the Allan Hills, Antarctica. Proceedings of the National Academy of Sciences, 112(22), pp.6887-6891. (doi:10.1073/pnas.1420232112)
2. Y. Yan, J. Ng, J. Higgins, A. Kurbatov, H. Clifford, N. Spaulding, J. Severinghaus, E. Brook, P. Mayewski, and M. Bender. 2.7-million-year-old ice from Allan Hills Blue Ice Areas, East Antarctica reveals climate snapshots since early Pleistocene. In Goldschmidt Abstracts, number 4359, 2017.
3. Y. Yan, M. Bender, E. Brook, H. Clifford, P. Kemeny, A. Kurbatov, S. Mackay, P. Mayewski, J. Ng, J. P. Severinghaus, and J. Higgins. 2-Million-Year-Old Climate Snapshots from Shallow Ice Cores in the Allan Hills, Antarctica. Nature (accepted) 2018-07-09202, 7 2018.
4. Yan, Y., Spaulding, N.E., Bender, M.L., Brook, E.J., Higgins, J.A., Kurbatov, A.V. and Mayewski, P.A., 2021. Enhanced Moisture Delivery into Victoria Land, East Antarctica During the Early Last Interglacial: Implications for West Antarctic Ice Sheet Stability. Climate of the Past, 17 (5), pp.1841–1855. (doi:10.5194/cp-17-1841-2021)
5. Stolper, D. A., Bender, M. L., Dreyfus, G. B., Yan, Y., & Higgins, J. A. (2016). A Pleistocene ice core record of atmospheric O2 concentrations. Science, 353(6306), 1427–1430. (doi:10.1126/science.aaf5445)
6. Yan, Y., Spaulding, N. E., Bender, M. L., Brook, E. J., Higgins, J. A., Kurbatov, A. V., & Mayewski, P. A. (2021). Enhanced Moisture Delivery into Victoria Land, East Antarctica During the Early Last Interglacial: Implications for West Antarctic Ice Sheet Stability. (doi:10.5194/cp-2021-7)
7. Yan, Y., Kurbatov, A. V., Mayewski, P. A., Shackleton, S., & Higgins, J. A. (2022). Early Pleistocene East Antarctic temperature in phase with local insolation. Nature Geoscience. (doi:10.1038/s41561-022-01095-x)