BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Marine carbon cycle dynamics in the southern high latitudes during
  the Mid-Pleistocene transition: new insights from the central South Pacif
 ic Ocean - Julia Gottschalk\, Kiel University
DTSTART:20251119T173000Z
DTEND:20251119T190000Z
UID:TALK237547@talks.cam.ac.uk
CONTACT:91369
DESCRIPTION:The mid-Pleistocene transition (MPT) is arguably the most enig
 matic long-term climate shift of the Quaternary and is characterized by in
 creasingly severe glacial conditions about 1.2 to 0.6 million years ago. A
 lthough the MPT was suggested to be linked with a continuous lowering of g
 lacial atmospheric CO2 (CO2\,atm) levels\, the processes underlying this C
 O2\,atm decline are incompletely understood. Here we compare two new benth
 ic foraminiferal (Cibicidoides/Cibicides sp.) d13C records reflecting Circ
 umpolar Deep Water (CDW)\, from central South Pacific International Ocean 
 Discovery Program Site U1541 (54.2°S\, 125.4°W\, 3606 m water depth) and
  Southeast Atlantic Ocean Drilling Program Site 1094 (53.2°S\, 05.1°E\, 
 2807 m water depth)\, with similar records from the global ocean to identi
 fy possible reorganizations in the oceanic respired carbon pool over the p
 ast 2 million years that may explain CO2\,atm changes across the MPT. We s
 how a good agreement between lower CDW d13C signatures in the central Sout
 h Pacific and in the Southeast Atlantic\, and a wide-spread glacial declin
 e in CDW d13C signatures across five Southern Ocean sites during the MPT. 
 This points at a contribution from reduced glacial CDW ventilation and inc
 reased glacial respired carbon storage in the Southern Ocean to the glacia
 l CO2\,atm decline across the MPT. We also highlight an Atlantic-Pacific S
 outhern Ocean-wide increase in the magnitude of deglacial CDW δ13C shifts
  during the MPT\, which coincides with an amplitude increase in glacial-in
 terglacial Antarctic Circumpolar Current flow strength variations (Lamy et
  al.\, 2024). This highlights that not only an increased Southern Ocean re
 spired carbon storage might have driven CO2\,atm variations across the MPT
  but also more efficient outgassing of that carbon during deglacial phases
  post-MPT. We will address potential linkages of glacial respired carbon s
 torage and deglacial outgassing to changes in Antarctic ice sheet dynamics
  and southern hemisphere westerlies across the MPT.\n\nReferences:\n\nLamy
 \, F.\, Winckler\, G.\, Arz\, H.\, Farmer\, J.\, Gottschalk\, J.\, Lembke-
 Jene\, L.\, Middleton\, J.L.\, et al.\, 2024. Five million years of Antarc
 tic Circumpolar Current strength variability. Nature 627\, 789–796. doi:
  10.1038/s41586-024-07143-3
LOCATION:Latimer Room\, Clare College
END:VEVENT
END:VCALENDAR