Global perturbation of the carbon cycle at the onset of the Miocene Climatic Optimum

Holbourn, Ann; Kuhnt, Wolfgang; Kochhann, Karlos Guilherme Diemer; Andersen, Nils; Meier, K J Sebastian

doi:10.1130/g36317.1

Cited by 220 publications

(250 citation statements)

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“…We analysed bulk organic carbon isotopes (d 13 C org ), total organic carbon (TOC), total nitrogen (TN), and C/N (atomic) ratio to explore environmental changes within the palaeo-lake. Before measuring the d 13 C org and TOC values, we followed the procedure described in Leng et al [34] to remove carbonates from the samples by immersing them in 10 % HCl until complete degassing of CO 2 . The values of d 13 C org and TOC were measured in the Isotope Laboratory of GeoZentrum Nordbayern, Friedrich Alexander Universität Erlangen Nürnberg, using a CE 1110 Elemental analyser connected online to a ThermoFisher Delta V plus mass spectrometer.…”

Section: Geochemical Samples and Methodsmentioning

confidence: 99%

“…The shift between Zones 1 and Zone 2 could reflect the cooling event Mi-2, although this event is dated around 16.0 Ma [58]. Alternatively, a ''peak warmth'' centred around 15.6 Ma has been described from the Pacific Ocean and Antarctica [2,6,8]. It is therefore possible that the boundary between Zones 1 and 2 is related to the end of the ''peak warmth''.…”

Section: Possible Mechanisms For Palaeoenvironmental Changementioning

confidence: 99%

“…The Miocene climate exhibited marked changes including the Mid-Miocene Climatic Optimum (MMCO, *15-17.0 Ma [2]) during which temperatures were inferred to be *3-8°C higher than preindustrial level [3,4]. The mechanisms leading to the MMCO are still debated [2], but evidence points to an increase in the concentration of atmospheric CO 2 [4].…”

Section: Introductionmentioning

confidence: 99%

“…Until now, the MMCO has been mainly investigated using marine isotopic data [1,2,5,6], since terrestrial outcrops are relatively scarce. In Antarctica, a palynological study and leaf wax geochemistry revealed a warmer and wetter climate than today, and demonstrated that Antarctica could support a tundra vegetation [7,8].…”

Section: Introductionmentioning

confidence: 99%

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Lake geochemistry reveals marked environmental change in Southwest China during the Mid Miocene Climatic Optimum

Lebreton-Anberrée

et al. 2016

Science Bulletin

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The Mid-Miocene Climatic Optimum (MMCO; *15-17 Ma) was one of the short-term climatic warm events that punctuated the Cenozoic long-term cooling trend. Because there are very few terrestrial records of this event, most of our understanding comes from marine cores. In this report, we first present new palaeomagnetic data that revises the dating of our 400 m-thick lacustrine section in Wenshan (Yunnan), previously thought to be Late Miocene. These new data suggest an older age, ca. 15.2-16.5 Ma, coinciding with the MMCO. We measured d 13 C on bulk organic matter (d 13 C org ), total organic carbon (TOC), total nitrogen (TN) and C/N ratios at a high sample resolution to: (1) reconstruct the palaeoenvironmental changes in the lake catchment area, and (2) infer mechanisms responsible for these changes. Our results show that all four geochemical parameters demonstrate that a strong environmental change occurred around the middle of the section, shortly after the C5Cn/C5Br geomagnetic reversal and the Early/Middle Miocene boundary at 15.97 Ma. We propose that the environmental shift may be due to a combination of a change in climate, which became cooler, together with a change in organic matter cycling within the lake. This study provides a new insight into the MMCO and demonstrates that although the MMCO was generally a warm event, it was also a time of climatic instability and abrupt environmental changes.Keywords Yunnan Á Mid-Miocene Climatic Optimum Á Bulk organic carbon isotopes (d 13 C org ) Á C/N ratio Á TOC Electronic supplementary material The online version of this article

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Section: Geochemical Samples and Methodsmentioning

confidence: 99%

Section: Possible Mechanisms For Palaeoenvironmental Changementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Lake geochemistry reveals marked environmental change in Southwest China during the Mid Miocene Climatic Optimum

Lebreton-Anberrée

et al. 2016

Science Bulletin

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“…Published proxy records of atmospheric CO 2 concentration show a decline from the Oligocene to the Miocene (6, 7) that is broadly contemporaneous with a strong minimum in the ∼2.4-My eccentricity cycle ∼24 My ago (8), which would promote continental ice sheet expansion if radiative forcing was the dominant control on ice volume. Previous studies using drill core records from the deep ocean demonstrate a climatic response to astronomical forcing for the Oligocene (9,10) and parts of the Miocene (11)(12)(13). However, to improve understanding of the behavior of the climate/cryosphere system, we need longer high-resolution records from strategic locations that capture the changing response of the high latitudes to the combined effects of CO 2 , astronomical forcing, and tectonic boundary conditions.…”

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confidence: 99%

Evolution of the early Antarctic ice ages

Liebrand

Bakker

Beddow

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

109

180

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Understanding the stability of the early Antarctic ice cap in the geological past is of societal interest because present-day atmospheric CO2 concentrations have reached values comparable to those estimated for the Oligocene and the Early Miocene epochs. Here we analyze a new high-resolution deep-sea oxygen isotope (δ18O) record from the South Atlantic Ocean spanning an interval between 30.1 My and 17.1 My ago. The record displays major oscillations in deep-sea temperature and Antarctic ice volume in response to the ∼110-ky eccentricity modulation of precession. Conservative minimum ice volume estimates show that waxing and waning of at least ∼85 to 110% of the volume of the present East Antarctic Ice Sheet is required to explain many of the ∼110-ky cycles. Antarctic ice sheets were typically largest during repeated glacial cycles of the mid-Oligocene (∼28.0 My to ∼26.3 My ago) and across the Oligocene−Miocene Transition (∼23.0 My ago). However, the high-amplitude glacial−interglacial cycles of the mid-Oligocene are highly symmetrical, indicating a more direct response to eccentricity modulation of precession than their Early Miocene counterparts, which are distinctly asymmetrical—indicative of prolonged ice buildup and delayed, but rapid, glacial terminations. We hypothesize that the long-term transition to a warmer climate state with sawtooth-shaped glacial cycles in the Early Miocene was brought about by subsidence and glacial erosion in West Antarctica during the Late Oligocene and/or a change in the variability of atmospheric CO2 levels on astronomical time scales that is not yet captured in existing proxy reconstructions.

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Global change across the Oligocene-Miocene transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

et al. 2016

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The Oligocene-Miocene transition (OMT) (~23 Ma) is interpreted as a transient global cooling event, associated with a large-scale Antarctic ice sheet expansion. Here we present a 2.23 Myr long high-resolution (~3 kyr) benthic foraminiferal oxygen and carbon isotope (δ 18 O and δ 13 C) record from Integrated Ocean Drilling Program Site U1334 (eastern equatorial Pacific Ocean), covering the interval from 21.91 to 24.14 Ma. To date, five other high-resolution benthic foraminiferal stable isotope stratigraphies across this time interval have been published, showing a~1‰ increase in benthic foraminiferal δ 18 O across the OMT. However, these records are still few and spatially limited and no clear understanding exists of the global versus local imprints. We show that trends and the amplitudes of change are similar at Site U1334 as in other high-resolution stable isotope records, suggesting that these represent global deep water signals. We create a benthic foraminiferal stable isotope stack across the OMT by combining Site U1334 with records from ODP Sites 926, 929, 1090, 1264, and 1218 to best approximate the global signal. We find that isotopic gradients between sites indicate interbasinal and intrabasinal variabilities in deep water masses and, in particular, note an offset between the equatorial Atlantic and the equatorial Pacific, suggesting that a distinct temperature gradient was present during the OMT between these deep water masses at low latitudes. A convergence in the δ 18 O values between infaunal and epifaunal species occurs between 22.8 and 23.2 Ma, associated with the maximum δ 18 O excursion at the OMT, suggesting climatic changes associated with the OMT had an effect on interspecies offsets of benthic foraminifera. Our data indicate a maximum glacioeustatic sea level change of 50 m across the OMT.

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Global perturbation of the carbon cycle at the onset of the Miocene Climatic Optimum

Cited by 220 publications

References 26 publications

Lake geochemistry reveals marked environmental change in Southwest China during the Mid Miocene Climatic Optimum

Lake geochemistry reveals marked environmental change in Southwest China during the Mid Miocene Climatic Optimum

Evolution of the early Antarctic ice ages

Global change across the Oligocene-Miocene transition: High-resolution stable isotope records from IODP Site U1334 (equatorial Pacific Ocean)

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