Simulating Miocene Warmth: Insights From an Opportunistic Multi-Model Ensemble (MioMIP1)

N. J. Burls*, C. D. Bradshaw, A. M. De Boer, N. Herold, M. Huber, M. Pound, Y. Donnadieu, A. Farnsworth, A. Frigola, E. Gasson, A. S. von der Heydt, D. K. Hutchinson, G. Knorr, K. T. Lawrence, C. H. Lear, X. Li, G. Lohmann, D. J. Lunt, A. Marzocchi, M. PrangeC. A. Riihimaki, A. C. Sarr, N. Siler, Z. Zhang

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)peer-review

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Abstract

The Miocene epoch, spanning 23.03–5.33 Ma, was a dynamic climate of sustained, polar amplified warmth. Miocene atmospheric CO2 concentrations are typically reconstructed between 300 and 600 ppm and were potentially higher during the Miocene Climatic Optimum (16.75–14.5 Ma). With surface temperature reconstructions pointing to substantial midlatitude and polar warmth, it is unclear what processes maintained the much weaker-than-modern equator-to-pole temperature difference. Here, we synthesize several Miocene climate modeling efforts together with available terrestrial and ocean surface temperature reconstructions. We evaluate the range of model-data agreement, highlight robust mechanisms operating across Miocene modeling efforts and regions where differences across experiments result in a large spread in warming responses. Prescribed CO2 is the primary factor controlling global warming across the ensemble. On average, elements other than CO2, such as Miocene paleogeography and ice sheets, raise global mean temperature by ∼2°C, with the spread in warming under a given CO2 concentration (due to a combination of the spread in imposed boundary conditions and climate feedback strengths) equivalent to ∼1.2 times a CO2 doubling. This study uses an ensemble of opportunity: models, boundary conditions, and reference data sets represent the state-of-art for the Miocene, but are inhomogeneous and not ideal for a formal intermodel comparison effort. Acknowledging this caveat, this study is nevertheless the first Miocene multi-model, multi-proxy comparison attempted so far. This study serves to take stock of the current progress toward simulating Miocene warmth while isolating remaining challenges that may be well served by community-led efforts to coordinate modeling and data activities within a common analytical framework.

Original languageEnglish
Article numbere2020PA004054
JournalPaleoceanography and Paleoclimatology
Volume36
Issue number5
Early online date1 Apr 2021
DOIs
Publication statusPublished - 24 May 2021

Bibliographical note

Funding Information:
N. J. Burls acknowledges the support from the National Science Foundation (NSF; AGS‐1844380 and OCN‐2002448), as well as the Alfred P. Sloan Foundation as a Research Fellow. A. M. De Boer acknowledges the support of the Swedish Research Council Project 2016‐03912. A. S. von der Heydt acknowledges the support by the program of the Netherlands Earth System Science Center (NESSC), financially supported by the Ministry of Education, Culture and Science (OCW) (Grant no. 024.002.001). D. K. Hutchinson acknowledges the support of FORMAS Grant 2018‐01621. C. D. Bradshaw acknowledges NERC Grant NE I006281/1 and a NERC PhD studentship. C. H. Lear acknowledges NERC Grant NE/P019102/1. D. J. Lunt and A. Farnsworth acknowledge NERC Grant NE/K014757/1. M. Huber and N. Herold acknowledge funding from the NSF P2C2 program for this project through Grant #1602905. E. Gasson acknowledges funding from the Royal Society and NERC Grant NE/T007397/1. The authors thank S. Sosdian, S. Modestou, and F. Sangiorgi for assistance in compiling the ocean temperature data.

Publisher Copyright:
© 2021. The Authors.

Keywords

  • Miocene
  • Miocene surface temperature synthesis
  • model intercomparison
  • paleoclimate
  • polar amplification

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