The Miocene: The Future of the Past. Issue 4 (27th April 2021)

• Record Type: Journal Article
• Authors: Steinthorsdottir, M.; Coxall, H. K.; de Boer, A. M.; Huber, M.; Barbolini, N.; Bradshaw, C. D.; Burls, N. J.; Feakins, S. J.; Gasson, E.; Henderiks, J.; Holbourn, A. E.; Kiel, S.; Kohn, M. J.; Knorr, G.; Kürschner, W. M.; Lear, C. H.; Liebrand, D.; Lunt, D. J.; Mörs, T.; Pearson, P. N.; Pound, M. J.; Stoll, H.; Strömberg, C. A. E.
• Is Part Of: Paleoceanography and paleoclimatology. Volume 36:Issue 4(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-04-27
• Subjects: climate modeling -- paleobiota -- paleoclimate -- paleoenvironments -- review -- the Miocene; Paleoceanography -- Periodicals; Paleoclimatology -- Periodicals; 551.46
• DOI: 10.1029/2020PA004037
• Languages: English
• ISSNs: 2572-4517

Abstract

Abstract: The Miocene epoch (23.03–5.33 Ma) was a time interval of global warmth, relative to today. Continental configurations and mountain topography transitioned toward modern conditions, and many flora and fauna evolved into the same taxa that exist today. Miocene climate was dynamic: long periods of early and late glaciation bracketed a ∼2 Myr greenhouse interval—the Miocene Climatic Optimum (MCO). Floras, faunas, ice sheets, precipitation, p CO2, and ocean and atmospheric circulation mostly (but not ubiquitously) covaried with these large changes in climate. With higher temperatures and moderately higher p CO2 (∼400–600 ppm), the MCO has been suggested as a particularly appropriate analog for future climate scenarios, and for assessing the predictive accuracy of numerical climate models—the same models that are used to simulate future climate. Yet, Miocene conditions have proved difficult to reconcile with models. This implies either missing positive feedbacks in the models, a lack of knowledge of past climate forcings, or the need for re‐interpretation of proxies, which might mitigate the model‐data discrepancy. Our understanding of Miocene climatic, biogeochemical, and oceanic changes on broad spatial and temporal scales is still developing. New records documenting the physical, chemical, and biotic aspects of the Earth system are emerging, and together provide a more comprehensive understanding of this important time interval. Here, we review the state‐of‐the‐art in Miocene climate, ocean circulation, biogeochemical cycling, ice sheet dynamics, and biotic adaptation research as inferred through proxy observations and modeling studies. Plain Language Summary: During the Miocene time period (∼23–5 million years ago), Planet Earth looked similar to today, with some important differences: the climate was generally warmer and highly variable, while atmospheric CO2 was not much higher. Continental‐sized ice sheets were only present on Antarctica, but not in the northern hemisphere. The continents drifted to near their modern‐day positions, and plants and animals evolved into the many (near) modern species. Scientists study the Miocene because present‐day and projected future CO2 levels are in the same range as those reconstructed for the Miocene. Therefore, if we can understand climate changes and their biotic responses from the Miocene past, we are able to better predict current and future global changes. By comparing Miocene climate reconstructions from fossil and chemical data to climate simulations produced by computer models, scientists are able to test their understanding of the Earth system under higher CO2 and warmer conditions than those of today. This helps in constraining future warming scenarios for the coming decades. In this study, we summarize the current understanding of the Miocene world from data and models. We also identify gaps in our understanding that need further research attention in the future. Key Points: Miocene floras, faunas, and paleogeography were similar to today and provide plausible analogs for future climatic warming The Miocene saw great dynamism in biotic and climate systems, but the reasons for these shifts are still not well understood The p CO2 ‐temperature‐ice relationships during major Miocene climate oscillations and transitions warrant further research