Antarctic Ice Sheet dynamics over the past 4 million years (ICEBERGS)

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We need a much more refined understanding of tipping points in the climate system to better assess the pace and magnitude of future global changes. Here, the role of the Antarctic Ice Sheet is crucial and heavily debated since its melting could rise global sea levels by up to 60 m. Instrumental climate records of the last two centuries lack the non-linear, threshold behavior often used in climate model projections; however, geological records indicate that large-scale and often irreversible shifts in the Earth system took place at such past tipping points. I wish to study the dynamics and ice-mass loss history of Antarctica through such critical tipping points over the past 4 million years, when either temperature, atmospheric carbon dioxide or global sea level were higher than today. Such times are the Last Interglacial, Marine Isotopic Stage 11, the Mid-Pleistocene Transition and the Mid-Pliocene Warm Period. I will focus on icebergs which are the big unknown although they contribute half of the total Antarctic ice-mass loss. Recently recovered IODP core material from and around Scotia Sea’s Iceberg Alley will be the geographic focus. This is the central pathway where Antarctic icebergs route through and finally melt down, accumulating iceberg-rafted debris in ocean sediment. This work will be complemented by further IODP and ODP sites from Antarctic key locations. Such a large-scale, circum-Antarctic work, which includes determining the iceberg source geochemically, has never been done before, nor has the Artificial Intelligence based method intended to utilize to cope with the vast amount of data, ever been implemented. Complementary studies shall conduct comparable grain-size analysis, generate dust indicators to establish the orbital-based chronology, and determine the source of icebergs on the Antarctic continent geochemically. Project ICEBERGS has the potential to provide fundamental insight into the timing and dynamics of past iceberg discharge history and to better assess associated global sea-level rise. This first, long-term Antarctic ice-mass loss reconstruction can also deliver much needed data for climate model calibration and hence impact a number of scientific fields.