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SUMMARY:Linking Glacial-Interglacial States to Multiple Equilibria of Clim
 ate - David Ferreira\, University of Reading
DTSTART:20181031T110000Z
DTEND:20181031T120000Z
UID:TALK113515@talks.cam.ac.uk
CONTACT:Caroline Holmes
DESCRIPTION:Glacial-interglacial cycles (GIC) are often described as an am
 plified global response of the climate to perturbations in solar radiation
  caused by oscillations of Earth’s orbit. However\, it remains unclear w
 hether internal feedbacks are large enough to account for the radically di
 fferent glacial and interglacial states. Here I will discuss a modeling st
 udy providing support for an alternative view: Glacial-interglacial states
  are multiple equilibria of the climate system that exist for the same ext
 ernal forcing. Multiple equilibria resembling glacial and interglacial sta
 tes can be found in a complex coupled general circulation model of the oce
 an-atmosphere-sea ice system. The multiple states are sustained by ice-alb
 edo feedback modified by ocean heat transport. In addition\, expansion/con
 traction of the Southern Hemisphere ice pack over regions of upwelling\, r
 egulating outgassing of CO2 to the atmosphere\, is the primary mechanism b
 ehind a ~100pm CO2 change between the two states.\nIf confirmed\, a link b
 etween GICs and multiple stable states may provide an answer to puzzling a
 spects of the GIC\, for example\, why their amplitude is so regular despit
 e the highly variable magnitude of insolation change during glacial termin
 ations. In our perspective\, the GIC’s amplitude is primarily set by the
  separation between the multiple states (an intrinsic property of the unpe
 rturbed system) rather than by the forcing. The latter then provides the 
 “kick” to trigger the transition from one state to the other.
LOCATION:British Antarctic Survey\, Innovation Centre\, Seminar Room 1
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