DATE2016-05-30 12:39:13
AUTHORSPolychronis Constantinos Tzedakis (3), Vasiliki Margari (3), Eleonora Regattieri (5), Luke Cameron Skinner (6), Laurie Menviel (2), John Hellstrom (1), David Hodell (6), Giovanni Zanchetta (4), Russell Drysdale (1)
  1. University Of Melbourne Melbourne (Australia)
  2. University Of New South Wales Sydney (Australia)
  3. University College London London (United Kingdom)
  4. University Of Pisa Pisa (Italy)
  5. Istituto Di Geologia Ambientale E Geoingegneria, Cnr Rome (Italy)
  6. University Of Cambridge Cambridge (United Kingdom)
ABSTRACTMarine and terrestrial records from the North Atlantic have suggested the presence of climate instability during the Last Interglacial (129-116 thousand years ago), but there is considerable ambiguity over the number, timing and geographic extent of reported oscillations and whether they involved interhemispheric changes. This arises from the lower signal-to-noise ratio of interglacial variability compared to glacial, and the uneven resolution and poor chronological control of palaeorecords. Here we address these issues first by combining marine and terrestrial proxies from the same deep-sea sequence on the Portuguese Margin and then placing them on a robust chronological framework of a speleothem record in Italy. These records have previously been shown to capture abrupt climate changes with high fidelity and to trace the oceanic bipolar-seesaw. In line with previous work, our records show that the strongest expression of climate instability leading to an activation of the bipolar-seesaw occurred during the transitions into (Heinrich Event 11) and out of the interglacial (cold-water event C24), associated with large freshwater discharges in the North Atlantic. In between, activation of the seesaw is not detected, consistent with smaller freshwater fluxes at times of reduced ice volume. However, our records independently document a pervasive intra-interglacial variability in the hydrological cycle of southern Europe, coherent with episodic cold water-mass expansions in the North Atlantic and consistent with the observed geographical pattern of climate changes in climate model experiments. The origin of this variability remains unclear.