NOTE THE CHANGE IN TIME: Friday Seminars will now be held 2-3pm !
Deglaciations and sea level
Two key issues in palaeoclimatology concern the maximum rates of past sea-level rises, and the ice-abedo involvement in potential state changes of climate sensitivity. Both require well-dated, and precise sea-level reconstructions. For Termination I, the last deglaciation, corals and other coastal landforms have been used to make very detailed sea-level record that are well dated. But do these sufficiently represent the uncertainties? I will go through an array of often-ignored problems. For older terminations, continuous sea-level records (e.g., Red Sea, Mediterranean Sea) offer better control, but not the absolute age control – so detailed frameworks are needed to establish both relative and absolute chronological comparisons with other key climate parameters. These introduce their own level of uncertainty. I will go through the main issues and the solutions that are being investigated.
Overall, Termination II has come out as one of the most promising intervals of time for palaeoclimate studies. First, because its sea-level history is simpler (essentially monotonic) and better understood than that for Termination I – in part this is because there is less short-term “noise” that complicates temporal comparisons. Second, because TII led into the Last Interglacial (LIG), the most recent time with sea level significantly (6-9 m) higher than today, for similar global temperatures. I conclude with a discussion of how understanding both TII and the preceding Penultimate Glacial Maximum (PGM) is critical to identifying why LIG sea-level was so high. This discussion affects the applicability of LIG sea-level values in future projections for anthropogenic global warming scenarios.