Deep water temperature, carbonate ion, and ice volume changes across the Eocene‐Oligocene climate transition

Pusz, A. E.; Thunell, Robert C.; Miller, Kenneth G.

doi:10.1029/2010pa001950

Cited by 66 publications

(105 citation statements)

References 167 publications

(308 reference statements)

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“…This cooling is associated with the "precursor" δ 18 O increase (EOT-1). The signifi cant fall in temperatures recorded in planktic and benthic foraminiferal Mg/Ca and TEX 86 through the latest Eocene supports the hypothesis that EOT-1 was a time of major climatic cooling and corroborates that the fi rst δ 18 O increase was mainly driven by a reduction in temperature and not an expansion of Antarctic ice volume Lear et al, 2008;Pusz et al, 2011). Still, the EOT-1 culminates in an inferred sequence boundary within the Pachuta Marl Member of the Yazoo Formation designated SB2 (Fig.…”

Section: Substantial Cooling Through the Eotsupporting

confidence: 64%

Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico

Wade

Houben

Quaijtaal

et al. 2012

Geology

101

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The Eocene-Oligocene transition (EOT; ca. 33-34 Ma) was a time of pronounced climatic change, marked by the establishment of continental-scale Antarctic ice sheets. The timing and extent of temperature change associated with the EOT is controversial. Here we present multiproxy EOT climate records (similar to 15-34 k.y. resolution) from St. Stephens Quarry, Alabama, USA, derived from foraminiferal Mg/Ca, delta O-18, and TEX86. We constrain sea-surface temperatures (SSTs) in the latest Eocene and early Oligocene and address the issue of climatic cooling during the EOT. Paleotemperatures derived from planktic foraminifera Mg/Ca and TEX86 are remarkably consistent and indicate late Eocene subtropical SSTs of >28 degrees C. There was substantial and accelerated cooling of SSTs (3-4 degrees C) through the latest Eocene "precursor" delta O-18 shift (EOT-1), prior to Oligocene Isotope-1 (Oi-1). Our multispecies planktic foraminiferal delta O-18 records diverge at the E/O boundary (33.7 Ma), signifying enhanced seasonality in the earliest Oligocene in the Gulf of Mexico

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Section: Substantial Cooling Through the Eotsupporting

confidence: 64%

Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico

Wade

Houben

Quaijtaal

et al. 2012

Geology

101

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“…Because the Eocene AIS landmask is smaller than modern, we area weight the effective forcing calculation for the ice sheet and we acknowledge that this difference in landmask size could introduce a level of uncertainty into the effective forcing and temperature response between the configurations. Numerous research groups have attempted to estimate Antarctic ice volume growth at the EOT (Miller et al, 1987(Miller et al, , 2009Edgar et al, 2007;Coxall et al, 2005;Lear et al, 2000;Katz et al, 2008;Pusz et al, 2011;DeConto et al, 2008;Liu et al, 2009). Estimates for Antarctic glacial extent during the EOT is still uncertain so our approach is simply one of many possible approaches and this work should be considered as an exploratory sensitivity study.…”

Section: Antarctic Sensitivity Study Methodsmentioning

confidence: 99%

Does Antarctic glaciation cool the world?

2013

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Abstract.In this study, we compare the simulated climatic impact of adding an Antarctic ice sheet (AIS) to the "greenhouse world" of the Eocene and removing the AIS from the modern world. The modern global mean surface temperature anomaly ( T ) induced by Antarctic Glaciation depends on the background CO 2 levels and ranges from −1.22 to −0.18 K. The Eocene T is nearly constant at ∼−0.25 K. We calculate an climate sensitivity parameter S [Antarctica] which we define as T divided by the change in effective radiative forcing ( Q Antarctica ) which includes some fast feedbacks imposed by prescribing the glacial properties of Antarctica.The main difference between the modern and Eocene responses is that a negative cloud feedback warms much of the Earth's surface as a large AIS is introduced in the Eocene, whereas this cloud feedback is weakly positive and acts in combination with positive sea-ice feedbacks to enhance cooling introduced by adding an ice sheet in the modern. Because of the importance of cloud feedbacks in determining the final temperature sensitivity of the AIS, our results are likely to be model dependent. Nevertheless, these model results suggest that the effective radiative forcing and feedbacks induced by the AIS did not significantly decrease global mean surface temperature across the Eocene-Oligocene transition (EOT −34.1 to 33.6 Ma) and that other factors like declining atmospheric CO 2 are more important for cooling across the EOT. The results illustrate that the efficacy of AIS forcing in the Eocene is not necessarily close to one and is likely to be model and state dependent. This implies that using EOT paleoclimate proxy data by itself to estimate climate sensitivity for future climate prediction requires climate models and consequently these estimates will have large uncertainty, largely due to uncertainties in modelling low clouds. AIS temperature sensitivityDuring the Eocene-Oligocene Transition (EOT) global climate deteriorated as the warm and ice-free conditions of the Eocene gave way to a colder, glaciated state in the early Oligocene (Lear et al., 2000;Zachos et al., 2001;DeConto and Pollard, 2003; Macksensen and Ehrmann, 1992;Scher et al., 2011;Hambrey and Barrett, 1993). Evidence now exists that the cooling (Liu et al., 2009;Eldrett et al., 2009;Zanazzi et al., 2007;Ivany et al., 2000) and glaciation (Lear et al., 2000;Edgar et al., 2007;Coxall et al., 2005;Miller et al., 2009;DeConto and Pollard, 2003;Zachos et al., 2001) that occurred across the EOT was caused by a drop in CO 2 mixing ratios from ∼ 1000 to ∼ 600 ppm (Pagani et al., 2011;Pearson et al., 2009). These values are in the likely range of values over the next century. The modern Earth system is currently in a glaciated state, but is showing signs of potentially losing glacier ice in the Arctic and Antarctic in the future (Joughin and Alley, 2011;Jacob et al., 2012;Velicogna, 2009;Chen et al., 2009;Pritchard et al., 2009;Liston and Hiemstra, 2011). Thus a major, unanswered question in future climate change prediction i...

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“…In the eastern equatorial Pacific, the Eocene-Oligocene climate change did not trigger a major shift towards increased productivity, but there is evidence for a shortlived rise in productivity and export production associated to the onset of sustained Antarctic glaciation (Coxall and Wilson, 2011). The increase in benthic foraminifera accumulation rate in the eastern equatorial Pacific and coeval opal accumulation in the Southern Ocean suggest that there is a link between both sites (Coxall and Wilson, 2011), such as an intensification of thermohaline circulation as interpreted for the earliest Oligocene (Miller and Tucholke, 1983;Wright and Miller, 1993;Thomas et al, 2008;Cramer et al, 2009;Coxall and Wilson, 2011;Pusz et al, 2011).…”

Section: Regional Shallow-marine Response To a Global Change?mentioning

confidence: 99%

Bryozoan beds in northern Italy as a shallow-water expression of environmental changes during the Oligocene isotope event 1

Jaramillo‐Vogel

Bover‐Arnal

Strasser

2016

Sedimentary Geology

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Shifts in carbonate-producing biotic communities in the geological record provide evidence of past environmental changes in the neritic realm. The shallow-marine Calcare di Nago Formation exposed in the San Valentino section (northern Italy) covers the Late Eocene and Earliest Oligocene. The succession is characterized by the occurrence of light-dependent biota such as coralline algae and larger benthic foraminifera. In the uppermost part of the section, however,\ the fossil association is dominated by bryozoans, which are filter-feeder organisms. This ca. 12 m thick interval locally contains up to 86% bryozoans, while coralline algae as well as larger benthic foraminifera are absent. Coralline algae and nummulitid foraminifera recover in the upper part of the bryozoan beds, whereas orthophragminids do not recover. The gradual disappearance of larger foraminifera and coralline algae within the bryozoan-dominated deposits is coeval with a pronounced positive shift in δ 13 C. Based on its biostratigraphic position, this positive shift is interpreted to be linked to the positive shift in δ 13 C recognized in deepsea records shortly above the Eocene-Oligocene boundary, which in turn is associated to the positive shift in δ 18 O leading to the Oi-1 (Oligocene isotope event 1) cooling phase. Total phosphorus content increases in the bryozoan beds, suggesting enhanced nutrient supply to the neritic ecosystem. This phosphorous peak is coeval with the globally recognized increment in ocean productivity around the Oi-1 and δ 13 C positive shift. Thus, disappearance of light-dependent biota and the dominance of bryozoans in the platform carbonates studied are interpreted to result not necessarily from a deepening of the depositional environment but from the combination of lower seasurface temperatures and the deterioration of underwater light conditions on account of elevated turbidity in surface waters, resulting from enhanced primary productivity. As bryozoan beds occur in several Italian localities around the Eocene-Oligocene boundary, they are interpreted to represent the regional expression of neritic carbonate depositional systems to global environmental changes occurring at the dawn of an ice-house Earth.

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Deep water temperature, carbonate ion, and ice volume changes across the Eocene‐Oligocene climate transition

Cited by 66 publications

References 167 publications

Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico

Multiproxy record of abrupt sea-surface cooling across the Eocene-Oligocene transition in the Gulf of Mexico

Does Antarctic glaciation cool the world?

Bryozoan beds in northern Italy as a shallow-water expression of environmental changes during the Oligocene isotope event 1

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