06 Apr 2023
 | 06 Apr 2023
Status: this preprint is currently under review for the journal CP.

Limited exchange between the deep Pacific and Atlantic oceans during the warm mid-Pliocene and MIS M2 "glaciation"

Anna Hauge Braaten, Kim A. Jakob, Sze Ling Ho, Oliver Friedrich, Eirik Vinje Galaasen, Stijn De Schepper, Paul A. Wilson, and Anna Nele Meckler

Abstract. The mid-Pliocene (3.3–3.0 Ma) is the most recent period in Earth’s history of sustained, global warmth analogous to predicted near-future climates. Despite considerable efforts to characterize and understand the climate dynamics of the mid-Pliocene, the deep ocean and its response to this warming remains poorly understood. Here we present new mid-Pliocene Mg/Ca and Δ47 (“clumped isotope”) temperatures from the deep Pacific and North Atlantic oceans. These records cover the transition from Marine Isotope Stage (MIS) M2 — considered the most pronounced “glacial” stage of the mid-Pliocene — to the warm KM5 interglacial. We find that a large (>4 °C) temperature gradient existed between these two basins throughout that interval, with the deep North Atlantic considerably warmer and likely saltier than at present. We interpret our results to indicate that the deep Pacific and North Atlantic oceans were bathed by water masses with very different physical properties during the mid-Pliocene, and that only limited deep oceanic exchange occurred between the two basins. Our results point to a fundamentally different mode of ocean circulation or mixing compared to the present, where heat and salt is distributed from the North Atlantic into the Pacific. The amplitude of cooling observed at both sites during MIS M2 suggests that changes in benthic δ18O associated with this cold stage were mostly driven by temperature change in the deep ocean rather than ice volume.

Anna Hauge Braaten et al.

Status: open (until 05 Jul 2023)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • CC1: 'Comment on cp-2023-13', Harry Dowsett, 27 Apr 2023 reply
  • RC1: 'Comment on cp-2023-13', Anonymous Referee #1, 15 May 2023 reply

Anna Hauge Braaten et al.

Anna Hauge Braaten et al.


Total article views: 615 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
466 135 14 615 27 4 10
  • HTML: 466
  • PDF: 135
  • XML: 14
  • Total: 615
  • Supplement: 27
  • BibTeX: 4
  • EndNote: 10
Views and downloads (calculated since 06 Apr 2023)
Cumulative views and downloads (calculated since 06 Apr 2023)

Viewed (geographical distribution)

Total article views: 603 (including HTML, PDF, and XML) Thereof 603 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
Latest update: 03 Jun 2023
Short summary
In the context of understanding current global warming, the middle Pliocene (3.3–3.0 million years ago) is an important interval in Earth's history because atmospheric carbon dioxide concentrations were similar to levels today. We have reconstructed deep sea temperatures at two different locations for this time, and find that a very different mode of ocean circulation or mixing existed, with important implications for how heat was transported in the deep ocean.