Miocene temperature portal

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Background

The Miocene — a warm period in the past

The Miocene, ~23⁠ – ⁠5 million years ago (Ma), was an interval of overall global warmth relative to the present day. The animals and plants of the Miocene included some quite familiar looking ancestors of modern flora and fauna (Figure 1). Many geographic and oceanic features were also similar to those of today. In fact, many characteristics of the Miocene make this interval of interest as a potential analog for future warm climate conditions. During the early to mid-Miocene (23⁠ – ⁠14 Ma) global temperatures and atmospheric carbon dioxide (CO₂) concentrations were similar to those projected in the coming centuries as a consequence of human-induced climate change^1–10. During the early to mid-Miocene, there was also a major collapse of the East Antarctic Ice Sheet, followed by regrowth and onset of a West Antarctic Ice Sheet in the late Miocene^11–17. Across the early to middle Miocene, tectonic reorganizations and closure of low latitude seaways played a role in climate change. By the middle Miocene global geography similar to today was achieved¹⁸.

Middle Miocene — warmhouse to icehouse

Global mean surface temperature during peak Miocene warmth, the Miocene Climate Optimum (MCO) (Figure 2), was 3⁠ – ⁠4 °C warmer than today (~17⁠ – ⁠14.7 Ma)¹⁹. Estimates of atmospheric CO₂ concentrations during the MCO range from ~580⁠ – ⁠670 ppm^3,4,7–9. This interval was followed by the Middle Miocene Climate Transition (MMCT), which was marked by a 2 °C cooling of deep ocean temperatures and a rapid expansion of the East and West Antarctic Ice Sheets at 14⁠ – ⁠13 Ma as reflected in a stepwise increase in benthic foraminiferal oxygen isotope ratios, a proxy for both ice volume and deep ocean temperature^14,16,17,20. CO₂ levels after the Miocene Climate Transition were 380⁠ – ⁠420 ppm^1,3,7. Proxy records show widespread cooling in regions around Antarctica and in the North Atlantic^9,16,21, a reorganization of polar fronts^22,23, and alterations in tropical climate patterns^24–26 across the MMCT.

The late Miocene — cooling and large ecosystem changes

The late Miocene (11 Ma to 5.3 Ma) was a time of enormous change in terrestrial environments and ecosystems, including the well documented expansion of C₄ grasslands (plants that used the C₄ photosynthetic pathway) across large swaths of the tropics and subtropics^26–28. A broad drying of the landscape in the subtropics²⁹ and a global radiation of succulent plant lineages also occurred³⁰. These floral changes were accompanied by large turnovers in terrestrial fauna^31,32. While benthic foraminiferal oxygen isotope records of the late Miocene (a proxy for both ice volume and deep ocean temperature) show no long-term trend³³, records of ocean surface temperature reveal substantial (~6 °C) interhemispheric cooling during the late Miocene³⁴. This disparity suggests that the late Miocene cooling did not lead to a significant permanent increase in continental ice volume and implies that in high latitude deep water formation regions waters were cold prior to the late Miocene.

Causes of Miocene climate change

Carbon cycle changes as well as changes in heat and moisture transport have been implicated as potential causes for the shifting climate conditions of the Miocene^26,35,36. Across the early to mid-Miocene, the carbon cycle shows dynamic changes with a long-lasting (~3.5 Myrs) positive carbon isotope excursion evident in foraminiferal records, with the onset of global warmth and reduced ice volume during the MCO. Following the MMCT and the shift from ‘warmhouse’ to icehouse climate state, the carbon isotopic ratio of the global ocean declined. Available records documenting Miocene carbon cycle changes hint at a dynamic interaction between volcanism, organic carbon burial, and weathering^26,37,38, including a large shift in how and where carbon is stored on land as Arctic tundra and permafrost biomes expanded ca. 6 Ma³⁶. Identifying the carbon cycle feedbacks at play during past warm intervals like the Miocene, when CO₂ was similar to our near future, is useful for anticipating potential future climatic changes. Understanding the mechanisms that drove the observed climatic shifts, is at the heart of Miocene climate research.

Abbreviations

TEX₈₆

Cyclization index of tetraethers is a ratio of 86-carbon tetraether lipids (GDGTs) which is sensitive to temperature and growth conditions. These organic compounds originate from ammonia-oxidizing Thaumarchaeota.

Mg/Ca

The ratio of magnesium to calcium in the shells of foraminifera is sensitive to the temperature of the water in which these organisms grew and can serve as a proxy for water temperature at a range of depths depending on the depth habitat of the organisms being analyzed.

Uᵏ'₃₇

The alkenone unsaturation index is the ratio of di- and tri-unsaturated ketones, which are organic compounds produced by a group of marine algae. This ratio is sensitive to organism growth temperature and thus the temperature of the sea surface.

Δ47

The clumped isotope paleothermometer is based on the difference between the measured and stochastic abundance of doubly substituted isotopologues of CO₂. This value is formation temperature controlled and typically measured on CO₂ derived from biogenic or inorganic carbonates.

SST

Sea surface temperature.

O/M boundary

The Oligocene/Miocene boundary (23.03 Ma)

Pre-MCO

Early-middle Miocene (23.03 – ~16.9 Ma)

MCO

The Miocene Climatic Optimum (~16.9 – 14.7 Ma)

Post-MCO

Middle-late Miocene (~14.7 – 5.33 Ma)

M/P boundary

The Miocene/Pliocene boundary (5.33 Ma)

Obtain paleo coordinates

If you wish to obtain paleolatitude and paleolongitude for any site, we recommend you use Geo Plates web service.

References

1. Badger MPS, Lear CH, Pancost RD, et al. CO2 drawdown following the middle Miocene expansion of the Antarctic Ice Sheet. Paleoceanography. 2013;28(1):42-53. https://doi.org/10.1002/palo.20015
2. Ekart DD, Cerling TE, Montanez IP, Tabor NJ. A 400 million year carbon isotope record of pedogenic carbonate: Implications for paleoatmospheric carbon dioxide. Am J Sci. 1999;299(10):805-827. https://doi.org/10.2475/ajs.299.10.805
3. Foster GL, Lear CH, Rae JWB. The evolution of pCO2, ice volume and climate during the middle Miocene. Earth Planet Sci Lett. 2012;341-344:243-254. https://doi.org/10.1016/j.epsl.2012.06.007
4. Greenop R, Foster GL, Wilson PA, Lear CH. Middle Miocene climate instability associated with high-amplitude CO2 variability. Paleoceanography. 2014;29(9):845-853. https://doi.org/10.1002/2014PA002653
5. Kürschner WM, Kvaček Z, Dilcher DL. The impact of Miocene atmospheric carbon dioxide fluctuations on climate and the evolution of terrestrial ecosystems. Proc Natl Acad Sci. 2008;105(2):449. https://doi.org/10.1073/pnas.0708588105
6. Retallack GJ. Refining a pedogenic-carbonate CO2 paleobarometer to quantify a middle Miocene greenhouse spike. Palaeogeogr Palaeoclimatol Palaeoecol. 2009;281(1):57-65. https://doi.org/10.1016/j.palaeo.2009.07.011
7. Sosdian SM, Greenop R, Hain MP, Foster GL, Pearson PN, Lear CH. Constraining the evolution of Neogene ocean carbonate chemistry using the boron isotope pH proxy. Earth Planet Sci Lett. 2018;498:362-376. https://doi.org/10.1016/j.epsl.2018.06.017
8. Steinthorsdottir M, Jardine PE, Rember WC. Near-Future pCO2 during the hot Mid Miocene Climatic Optimum. Paleoceanogr Paleoclimatology. 2020;n/a(n/a):e2020PA003900. https://doi.org/10.1029/2020PA003900
9. Super JR, Thomas E, Pagani M, Huber M, O’Brien C, Hull PM. North Atlantic temperature and pCO2 coupling in the early-middle Miocene. Geology. 2018;46(6):519-522. https://doi.org/10.1130/G40228.1
10. Zhang YG, Pagani M, Liu Z, Bohaty SM, DeConto R. A 40-million-year history of atmospheric CO2. Philos Trans R Soc Math Phys Eng Sci. 2013;371(2001):20130096. https://doi.org/10.1098/rsta.2013.0096
11. Gasson E, DeConto RM, Pollard D, Levy RH. Dynamic Antarctic ice sheet during the early to mid-Miocene. Proc Natl Acad Sci. 2016;113(13):3459. https://doi.org/10.1073/pnas.1516130113
12. Greenop R, Sosdian SM, Henehan MJ, Wilson PA, Lear CH, Foster GL. Orbital Forcing, Ice Volume, and CO2 Across the Oligocene-Miocene Transition. Paleoceanogr Paleoclimatology. 2019;34(3):316-328. https://doi.org/10.1029/2018PA003420
13. John CM, Karner GD, Browning E, et al. Timing and magnitude of Miocene eustasy derived from the mixed siliciclastic-carbonate stratigraphic record of the northeastern Australian margin. Earth Planet Sci Lett. 2011;304(3):455-467. https://doi.org/10.1016/j.epsl.2011.02.013
14. Lear CH, Coxall HK, Foster GL, et al. Neogene ice volume and ocean temperatures: Insights from infaunal foraminiferal Mg/Ca paleothermometry. Paleoceanography. 2015;30(11):1437-1454. https://doi.org/10.1002/2015PA002833
15. Levy R, Harwood D, Florindo F, et al. Antarctic ice sheet sensitivity to atmospheric CO2 variations in the early to mid-Miocene. Acton G, Askin R, Atkins C, et al., eds. Proc Natl Acad Sci. 2016;113(13):3453–3458. https://doi.org/10.1073/pnas.1516030113
16. Shevenell AE, Kennett JP, Lea DW. Middle Miocene ice sheet dynamics, deep-sea temperatures, and carbon cycling: A Southern Ocean perspective. Geochem Geophys Geosystems. 2008;9(2). https://doi.org/10.1029/2007GC001736
17. Westerhold T, Marwan N, Drury AJ, et al. An astronomically dated record of Earth’s climate and its predictability over the last 66 million years. Science. 2020;369(6509):1383–1387. https://doi.org/10.1126/science.aba6853
18. Herold N, Seton M, Müller RD, You Y, Huber M. Middle Miocene tectonic boundary conditions for use in climate models. Geochem Geophys Geosystems. 2008;9(10). https://doi.org/10.1029/2008GC002046
19. You Y, Huber M, Müller RD, Poulsen CJ, Ribbe J. Simulation of the Middle Miocene Climate Optimum. Geophys Res Lett. 2009;36(4). https://doi.org/10.1029/2008GL036571
20. Lear CH, Mawbey EM, Rosenthal Y. Cenozoic benthic foraminiferal Mg/Ca and Li/Ca records: Toward unlocking temperatures and saturation states. Paleoceanography. 2010;25(4). https://doi.org/10.1029/2009PA001880
21. Lewis AR, Marchant DR, Ashworth AC, Hemming SR, Machlus ML. Major middle Miocene global climate change: Evidence from East Antarctica and the Transantarctic Mountains. GSA Bull. 2007;119(11-12):1449-1461. https://doi.org/10.1130/0016-7606(2007)119[1449:MMMGCC]2.0.CO;2
22. Kuhnert H, Bickert T, Paulsen H. Southern Ocean frontal system changes precede Antarctic ice sheet growth during the middle Miocene. Earth Planet Sci Lett. 2009;284(3):630-638. https://doi.org/10.1016/j.epsl.2009.05.030
23. Verducci M, Foresi LM, Scott GH, Sprovieri M, Lirer F, Pelosi N. The Middle Miocene climatic transition in the Southern Ocean: Evidence of paleoclimatic and hydrographic changes at Kerguelen plateau from planktonic foraminifers and stable isotopes. Palaeogeogr Palaeoclimatol Palaeoecol. 2009;280(3):371-386. https://doi.org/10.1016/j.palaeo.2009.06.024
24. Holbourn A, Kuhnt W, Regenberg M, Schulz M, Mix A, Andersen N. Does Antarctic glaciation force migration of the tropical rain belt? Geology. 2010;38(9):783-786. https://doi.org/10.1130/G31043.1
25. Rousselle G, Beltran C, Sicre MA, Raffi I, De Rafelis M. Sea-surface condition changes in the Equatorial Pacific during the Mio-Pliocene as inferred from coccolith geochemistry. Earth Planet Sci Lett. 2013;361:412-421. https://doi.org/10.1016/j.epsl.2012.11.003
26. Sosdian SM, Babila TL, Greenop R, Foster GL, Lear CH. Ocean Carbon Storage across the middle Miocene: a new interpretation for the Monterey Event. Nat Commun. 2020;11(1):134. https://doi.org/10.1038/s41467-019-13792-0
27. Cerling TE, Harris JM, MacFadden BJ, et al. Global Vegetation change through the Miocene/Pliocene boundary. Nature. 1997;389:153-158. https://doi.org/10.1038/38229
28. Ehleringer JR, Cerling TE, Helliker BR. C4 photosynthesis, atmospheric CO2, and climate. Oecologia. 1997;112(3):285-299. https://doi.org/10.1007/s004420050311
29. Strömberg CAE. Evolution of Grasses and Grassland Ecosystems. Annu Rev Earth Planet Sci. 2011;39(1):517-544. https://doi.org/10.1146/annurev-earth-040809-152402
30. Dupont LM, Rommerskirchen F, Mollnehauer G, Schefub E. Miocene to Pliocene changes in South African hydrology and vegetation in relation to the expansion of C4 Plants. Earth Planet Sci Lett. 2013;375:408-417. https://doi.org/10.1016/j.epsl.2013.06.005
31. Arakaki M, Christin P-A, Nyffeler R, et al. Contemporaneous and recent radiations of the world’s major succulent plant lineages. Proc Natl Acad Sci. 2011;108(20):8379-8384. https://doi.org/10.1073/PNAS.1100628108
32. Badgley C, Barry JC, Morgan ME, et al. Ecological changes in Miocene mammalian record show impact of prolonged climatic forcing. Proc Natl Acad Sci. 2008;105(34):12145. https://doi.org/10.1073/pnas.0805592105
33. Wang Y, Cerling TE, MacFadden BJ. Fossile horses and carbon isotopes: new evidence for Cenozoic dietary, habitat, and ecosystem changes in North America. Palaeogeogr Palaeoclimatol Palaeoecol. 1994;107:269-279. https://doi.org/10.1016/0031-0182(94)90099-X
34. Zachos J, Pagani M, Sloan LC, Thomas E, Billups K. Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present. Science. 2001;292:686-693. https://doi.org/10.1126/science.1059412
35. Herbert TD, Lawrence KT, Tzanova A, Peterson LC, Caballero-Gill R, Kelly CS. Late Miocene global cooling and the rise of modern ecosystems. Nat Geosci. 2016;9:843-847. https://doi.org/10.1038/ngeo2813
36. De Vleeschouwer D, Drury AJ, Vahlenkamp M, Rochholz F, Liebrand D, Pälike H. High-latitude biomes and rock weathering mediate climate–carbon cycle feedbacks on eccentricity timescales. Nat Commun. 2020;11(1):5013. https://doi.org/10.1038/s41467-020-18733-w
37. Raymo ME. The Himalayas, organic carbon burial, and climate in the Miocene. Paleoceanography. 1994;9(3):399-404. https://doi.org/10.1029/94PA00289
38. Hodell DA, Woodruff F. Variations in the strontium isotopic ratio of seawater during the Miocene: Stratigraphic and geochemical implications. Paleoceanography. 1994;9(3):405-426. https://doi.org/10.1029/94PA00292
39. Steinthorsdottir M, Coxall HK, de Boer AM, Huber M, Barbolini N, Bradshaw CD, et al. The Miocene: the Future of the Past. Paleoceanography and Paleoclimatology. 2020;35:e2020PA004037. https://doi.org/10.1029/2020PA004037
40. Burls NJ, Bradshaw CD, De Boer AM, Herold N, Huber M, Pound M, Donnadieu Y, Farnsworth A, Frigola A, Gasson E, von der Heydt AS, Hutchinson DK, Knorr G, Lawrence KT, Lear CH, Li X, Lohmann G, Lunt DJ, Marzocchi A, Prange M, Riihimaki CA, Sarr A-C, Siler N, Zhang Z. Simulating Miocene warmth: insights from an opportunistic Multi-Model ensemble (MioMIP1). Paleoceanography and Paleoclimatology. 2021. https://doi.org/10.1029/2020PA004054

Data description

This dataset consists of a table with key information about published Miocene temperature records, which can be downloaded as a comma-separated values (csv) text file having the following content for each site:

• Site name
• Type of temperature record
• Ocean basin
• Proxy data type
• Modern latitude (degrees, positive is North)
• Modern longitude (degrees, positive is East)
• Modern sea surface temperature (°C)
• Modern bottom water temperature (°C) (if applicable)
• Modern water depth (m)
• Paleo water depth (m) (if applicable)
• Age description (see list with abbreviations for definitions)
• Starting age (Ma)
• Ending age (Ma)
• Average Sample Resolution (kyr)
• References to papers describing the data
• Data repository
• Web address to the data

The csv file is saved with utf-8 encoding. It can be opened in any standard text editor, spreadsheet or other data analysis software. Several guides for how to import this type of file in Excel are available on the web, e.g. at the Institute for Advanced Study.

Comments

The initial compilation of data available here was prepared for the article Simulating Miocene warmth: insights from an opportunistic multi-model ensemble (MioMIP1) by Burls et al (2021)⁴⁰.

Contact persons

[javascript protected email address] is a John H. Markle Professor of Geology & Environmental Geosciences, Lafayette College, 4 South College Drive, Easton, PA 18042, USA.

[javascript protected email address] is Docent Senior Lecturer in Marine Micropaleontology at the Department of Geological Sciences, Stockholm University and co-leader of the Research Area 6: Deep Time climate variability of the Bolin Centre for Climate Research.

[javascript protected email address] is a Senior Lecturer in Marine Biogeochemistry at the School of Earth & Environmental Sciences, Cardiff University, Cardiff, CF10 3AT, UK.

[javascript protected email address] is a researcher in palaeoclimate at the Department of Palaeobiology, Swedish Museum of Natural History and co-leader of Research Area 6: Deep Time climate variability of the Bolin Centre for Climate Research.

Acknowledgements

Thanks to Natalie Burls, Matthew Huber, Sevasti Modestou, Francesca Sangiorgi, Timothy Herbert, Carrie Lear, and Ann Pearson for their contribution to this data portal.