The role of ocean gateways on cooling climate on long time scales

• Main Authors: Sijp, Willem P., von der Heydt, Anna S., Dijkstra, Henk A., Floegel, Sascha, Douglas, Peter M. J., Bijl, Peter K.
• Other Authors: Sub Physical Oceanography, Marine palynology and palaeoceanography, Marine and Atmospheric Research, Marine Palynology
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Eocene; Cenozoic cooling trend; deep ocean cooling; ocean gateways; thermal isolation; ocean circulation; Eocene/Oligocene transition; Deep time climate model; Polar amplification; Cloud feedbacks; overturning circulation; AMOC; THC; greenhouse climate; icehouse climate; polar warmth; ANTARCTIC CIRCUMPOLAR CURRENT; ATMOSPHERIC CARBON-DIOXIDE; SEA-SURFACE TEMPERATURES; BENTHIC FORAMINIFERAL MG/CA; SOUTHWEST PACIFIC-OCEAN; NORTHERN HIGH-LATITUDES; STABLE-ISOTOPE RECORDS; DRAKE PASSAGE GATEWAY; DEEP-WATER PRODUCTION; EARLY EOCENE; Antarctic; Drake Passage; Pacific; Southern Ocean; The Antarctic; Antarc*
• Online Access: https://dspace.library.uu.nl/handle/1874/306096

We examine ocean changes in response to changes in paleogeography from the Cretaceous to present in an intermediate complexity model and in the fully coupled CCSM3 model. Greenhouse gas concentrations are kept constant to allow a focus on effects arising from changing continental configurations. We find consistent and significant geography-related Cenozoic cooling arising from the opening of Southern Ocean (SO) gateways. Both models show significant deep ocean cooling arising from tectonic evolution alone. Simulations employing continental configurations associated with greenhouse climates, namely the Turonian and the Eocene simulations, systematically exhibit warm deep ocean temperatures at elevated pCO(2) close to 10 degrees C. In contrast, continental configurations associated with (later) icehouse climates are associated with cooler deep ocean temperatures at identical pCO(2), arising from a progressive strengthening of the Antarctic Circumpolar Current. This suggests that a component of the Cenozoic benthic cooling trend recorded in oxygen isotopes could arise directly from changes in continental configuration, and so be partially decoupled from the Cenozoic greenhouse gas history. In this paper we will present our model results against the background of an extensive review of previous work on ocean gateways and additional modelling results from several other global climate models. (C) 2014 Elsevier B.V. All rights reserved.