Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 1-22 |
| Number of pages | 22 |
| Journal | Global and Planetary Change |
| Volume | 119 |
| DOIs | |
| Publication status | Published - Aug 2014 |
Funding
We thank the University of Victoria staff for support in usage of their coupled climate model. This research was supported by the Australian Research Council (Sijp, project DP1096144) and the Australian Antarctic Science Program. Linda C. Ivany provided data and helpful discussions regarding Seymour Island d<SUP>18</SUP>O data. We thank the scientists from the SourceRock project (funded by Senter Novem) for providing us with the results of the CCSM simulations. In particular, we thank Roderik van de Wal, Joao Trabucho Alexandre and Erik Tuenter for making Fig. 9 in this paper and Michael Kliphuis for performing the CT1250 and PD1250 CCSM3 simulations. AH thanks the Netherlands Organization for Scientific Research (NWO) for funding through project ALW 802.01.024. PKB thanks the NWO for funding through VENI grant number 863.13.002. The CCSM computations were done on the Huygens and Cartesius at SURFsara in Amsterdam. Use of the SURFsara computing facilities was sponsored by NWO under the project SH-209-12. We thank Robbie Toggweiler for an insightful review of the paper.
Keywords
- 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
