Séminaire EPOC : Gianluca Marinole 15 décembre 2016 à 11h
Le prochain séminaire EPOC "Processes controlling the ice-age cycles: insights from the last two glacial terminations", donné par Gianluca Marino (Australian National University, Canberra) aura lieu le jeudi 15 décembre à 11 h, en salle Atmosphère.
Research School of Earth Sciences, The Australian National University, Canberra, Australia.
Over the last million years the Earth's climate repeatedly fluctuated between ice and warm ages with a ~100,000 years periodicity. Ice-age cycles developed in response to changes in the Earth's orbit and superimposed climate feedbacks (e.g., atmospheric CO2 concentrations) and exhibit an overall 'sawtooth' structure, with gradual global cooling and ice-volume build-up, followed by rapid warming and melting at glacial terminations. The rapidity of these events calls for a robust chronological control to constrain the processes that terminate an ice age. Absolute dating of palaeoclimate archives from polar ice sheets, ocean basins, and land can be directly obtained only for Termination I (T-I), which has been historically used as a template to understand previous terminations. We recently developed an equally robust, radiometrically constrained chronology for key Northern and Southern Hemisphere records spanning Termination II (T-II), and the last interglacial period. I will discuss how this work: (i) reveals the sequence of climate events that characterised T-II; (ii) allows the comparison – in millennial scale detail – of the timing of ocean, climate, and ice-volume changes between T-II and of T-I; and, in turn, (iii) provides novel insights into the debate on the forcing and feedback mechanisms of the ice age cycles.