From snow pits to a million year ice-core: taking the measure of the planet from Antarctica
1Australian Antarctic Division, Kingston TAS, Australia, 2Australian Antarctic Program Partnership, Institute for Marine and Antarctic Studies, University of Tasmania
The Antarctic Ice Sheet stores a detailed record of climate and atmospheric composition that spans seasonal to orbital timescales. From snow pit studies of monthly variability in the fallout of radio-nuclides, to kilometre-deep ice core studies of the Quaternary glacial cycles, the Antarctic ice sheet is a place to take the measure of the planet.
A network of Antarctic ice cores now provides a continuous record of past climate and atmospheric composition that reaches back 800,000 years. These data demonstrate the close coupling between the carbon cycle and Earth’s climate. In particular, providing the clearest known evidence that changes in atmospheric CO2 accompanied and contributed to driving the ice age cycles that dominated climate, sea level and ice sheet variability over this interval. The data also provide important context for current observations: CO2 levels are clearly higher and rising orders of magnitude faster than at any time in the ice core record.
The next frontier in ice core science is to recover a continuous ice core that reaches back well beyond a million years. This ‘oldest ice challenge’ is significant because between 800,000 years and ca. 1.2 million years there is a major change in the climate state—the Mid Pleistocene Transition (MPT)—during which glacial ice volume declines and the periodicity of glacial cycles quickens from 100,000 years to 41,000 years. Multiple nations have initiated projects to recover the oldest ice in order to test competing hypotheses on the climate, cryosphere and carbon cycle feedbacks involved in this transition. By sampling the MPT climate state and advancing our understanding of the processes involved, we also advance understanding of how these same feedbacks may respond in the future.
I will provide an overview of the Australian Antarctic Program’s response to the oldest ice challenge—The Million Year Ice Core Project. Our drilling commences this summer at ‘Little Dome C’, where radar surveys and modelling indicate that undisturbed 1.5 million-year-old ice is likely present. Our project is collaborating with the European Beyond Oldest Ice Core (BE-OIC) project, who are also drilling in this region. Multiple cores are important to verify that results are not affected by flow disturbance or other artefacts.
Dr Joel Pedro – Lead Project Scientist, Million Year Ice Core Project
Australian Antarctic Division
Qualifications: BSc (UWA), BSc Hons (UTas), PhD (UTas)
Dr Joel Pedro is Lead Project Scientist on the AAD’s Million Year Ice Core (MYIC) Project. The goal of his group is to drill, measure and interpret a continuous ice core record spanning at least 1.2 million years of Earth’s climate and atmospheric history.
Joel’s work applies observational and modelling approaches to a wide range of topics in Quaternary palaeoclimate, climate dynamics and glaciology. His work has spanned cosmogenic 10Be in Antarctic surface snow to CO2 in the deep ice core record. A particular focus is testing hypotheses on the atmosphere, ocean and cryosphere interactions responsible for millennial to orbital-scale climate transitions. His research highlights include Pedro et al., Clim. Past, 2012, which shows there is no significant time lag between the Antarctic temperature and atmospheric CO2 increases during the last deglaciation, Pedro et al., Nature Geosci., 2016, which maps the spatial extent and dynamics of the Antarctic Cold Reversal across the Southern Hemisphere, and Pedro et al., Quat. Sci. Rev., 2018, which advances a process understanding of inter-hemispheric climate coupling during past periods of abrupt climate change.
Joel completed undergraduate studies (Chemistry, Hydrology) at the University of Western Australia followed by Honours and PhD studies at the University of Tasmania, in collaboration with the Australian Nuclear Science and Technology Organisation. Prior to returning to Australia for his current role, he completed a JISAO Postdoc Fellowship at the University of Washington and a Marie Curie Postdoc Fellowship at the University of Copenhagen.
Joel has conducted ice core field work in Antarctica, Greenland and the sub-Antarctic islands. This summer he goes south to commence drilling of the Million Year Ice Core.