Antarctic ice sheets are destabilizing because Southern Ocean warming causes basal melt. It is unknown how these processes will develop during future climate warming, which creates an inability to project ice sheet melt and thus global sea level rise scenarios into the future. Studying past geologic episodes, during which atmospheric carbon dioxide levels (CO2) were similar to those projected for this century and beyond, is the only way to achieve mechanistic understanding of long-term ice sheet- and ocean dynamics in warm climates. Past ocean-induced ice sheet melt is not resolved because of a paucity of quantitative proxies for past ice-proximal oceanographic conditions: sea ice, upwelling of warm water and latitudinal temperature gradients. This hampers accurate projections of future ice sheet melt and sea level rise.
OceaNice will provide an integral understanding of the role of oceanography in ice sheet behavior during past warm climates, as analogy to the future. I will quantify past sea ice, upwelling of warm water and latitudinal temperature gradients in three steps:
1. Calibrate newly developed dinoflagellate cyst and biomarker proxies for past oceanographic conditions to glacial-interglacial oceanographic changes. This yields quantitative tools for application further back in time.
2. Apply these to two past warm climate states, during which CO2 was comparable to that of the future under strong and moderate fossil fuel emission mitigation scenarios.
3. Interpolate between new reconstructions using high-resolution ocean circulation modelling for circum-Antarctic quantification of past oceanographic conditions, which will be implemented into new ice sheet model simulations.
The groundbreaking new insights will deliver mechanistic understanding and quantitative estimates of ice-proximal oceanographic changes and consequent ice sheet melt during past warm climates, which will finally allow accurate future sea level rise projections given anticipated warming.
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