Talk by Joel Pedro
Title: The Million Year Ice Core: Australia’s Oldest Ice Project
J. Pedro1,2*, D. Baggenstos1,2, M. Curran1,2, D. Etheridge2,3, L. Jong1,2, L. Kock1, T. Lyons1, A. Menking2,3, A. Moy1,2, M. Nation1,2, C. Plummer2, A. Pepper1,, J. Roberts1,2, A.M. Smith4, T. van Ommen1,2
2 Australian Antarctic Program Partnership (AAPP), Institute for Marine and Antarctic Studies (IMAS), University of Tasmania, Hobart, Tasmania, Australia
3 Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organisation (CSIRO), Aspendale, Victoria, Australia
4 Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights NSW, Australia
*Corresponding author, e-mail: joel.pedro@aad.gov.au
The aim of the Australian Million Year Ice Core Project (MYIC), in the framework of the International Partnership in Ice Core Sciences (IPICS) oldest ice challenge, is to drill and recover a continuous Antarctic ice core that extends to well over a million years ago. An ice core covering this period will enable us to investigate climate links between temperature and carbon dioxide during the mid-Pleistocene Transition, when the Earth's ice age cycles changed pacing from 41,000 to 100,000 year periodicity. The main objective of the project is to test competing hypotheses on the cause of this non-linear shift in the Earth's climate state, with reconstruction of the relative timing and amplitude of glacial cycles beyond 800 kyr and the associated changes in atmospheric composition and biogeochemical markers.
The target drilling location for MYIC is in the Little Dome C region at 122.52059 °E, 75.34132 °S, approximately 35 km SW from Concordia Station. Radar surveys of the surrounding area show the MYIC site is on a topographic high ridge, separated by a valley from the new Beyond EPICA Oldest Ice (BE-OI) site, 5.2 km away. One-dimensional ice modelling, constrained by ice penetrating radar and isochrones traced back to the EPICA Dome C ice core site, indicate an age above the basal ice at the MYIC site of at least 1.4 million years, resolution better than 14 thousand years per metre, and regular internal layers with minimal basal melting. The final site selection involved consideration between MYIC and BE-OI researchers of the added value of the parallel drilling efforts at Little Dome C in overall risk mitigation and recover of independent records for joint replication and verification.
The Australian Antarctic Division (AAD) is upgrading its ice core analysis capabilities for the oldest ice challenge. This includes development of a continuous flow analysis (CFA) facility and a new ice core gas laboratory. The CFA capability will measure conductivity, particles, hydrogen peroxide, water isotopes and Na+ and Ca2+ ions, supplemented by ion chromatography on collected fractions. The CFA system will also be configured for continuous water isotope and continuous CH4 measurements using Picarro analysers. The new gas laboratory will combine a small sample sublimation extraction system coupled to a Quantum Cascade Laser spectrometer and dual inlet mass spectrometry for CO2, δ13C-CO2, CH4, and N2O as well as the main air isotopes. Other ice core measurements, including of cosmogenic radionuclides and radiometric dating markers, will be explored through national and international collaboration.
A new AAD deep ice core drill had been built in house by the AAD for the project, based on the US FORO 3000 design. Planning is underway to establish the MYIC drilling camp in the 2022/23 austral summer season, via a 1300-km traverse from Australia’s Casey Station. Traverse operations will support the ‘Inland Station’ MYIC drilling camp throughout the project. Drilling is expected
Speaker: Joel Pedro from the Australian Antarctic Division in Hobart (Tasmania). He is the scientific lead of Australians' Million-Year Ice Core, aiming to also get very old ice from East Antarctica.