Neodymium isotopic reconstruction of late Paleocene–early Eocene thermohaline circulation

Thomas, Deborah J; Bralower, Timothy J.; Jones, Charles E.

doi:10.1016/s0012-821x(03)00096-7

Cited by 175 publications

(177 citation statements)

References 51 publications

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“…beginning at the onset of the event. Carbon and oxygen isotopic analyses on planktonic foraminifera inferred to have inhabited the thermocline (Subbotina) are close to those of benthic foraminifera, consistent with inferences that the southern ocean was a source of deepwater at this time (Pak and Miller, 1992;Thomas et al, 2003).…”

Section: Surface Ocean/atmosphere Shiftsupporting

confidence: 72%

Bolide summer: The Paleocene/Eocene thermal maximum as a response to an extraterrestrial trigger

Cramer

Kent

2005

Palaeogeography, Palaeoclimatology, Palaeoecology

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The standard paradigm that the Paleocene/Eocene thermal maximum (PETM) represents a threshold event intrinsic to Earth's climate and connected in some way with long-term warming has influenced interpretations of the geochemical, climate, and biological perturbations that occurred at this event. As recent high-resolution data have demonstrated that the onset of the event was geologically instantaneous, attempts to account for the event solely through endogenous mechanisms have become increasingly strained. The rapid onset of the event indicates that it was triggered by a catastrophic event which we suggest was most likely a bolide impact. We discuss features of the PETM that require explanation and argue that mechanisms that have previously been proposed either cannot explain all of these features or would require some sort of high-energy trigger. A bolide impact could provide such a trigger and, in the event of a comet impact, could contribute directly to the shape of the carbon isotope curve. We introduce a carbon cyle model that would explain the PETM by global warming following a bolide impact, leading to oxidation of terrestrial organic carbon stores built up during the late Paleocene. Our intention is to encourage other researchers to seriously consider an impact trigger for the PETM, especially in the absence of plausible alternative mechanisms.

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Section: Surface Ocean/atmosphere Shiftsupporting

confidence: 72%

Bolide summer: The Paleocene/Eocene thermal maximum as a response to an extraterrestrial trigger

Cramer

Kent

2005

Palaeogeography, Palaeoclimatology, Palaeoecology

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“…Although it is difficult to infer meridional overturning circulation polarity for the Turonian, Cramer et al (2009) argue that more homogeneous deep ocean conditions before the late Eocene arose from deep sinking in both hemispheres, and that a period of enhanced heterogeneity during the late Cretaceous may have arisen from changes in the ability of winds to make water in the deep ocean circulate via a Tethyan circum-equatorial current that might have functioned in analogous fashion to the Antarctic Circumpolar Current (Hotinski and Toggweiler, 2003). For the Eocene, Corfield and Norris (1996), Thomas et al (2003), Thomas (2004), Via and Thomas (2006) and Coxall and Pearson (2007) find proxy evidence for deep ocean ventilation from the south. A further discussion of the warm polar conditions during the greenhouse climates, including terrestrial proxies, can be found in Sijp et al (2014).…”

Section: Comparison With Data Inferred From Proxiesmentioning

confidence: 99%

“…There are two proposed driving mechanisms of the present Atlantic Meridional Overturning Circulation (Kuhlbrodt et al, 2007), involving a balance between deep sinking and low-latitude diapycnal upwelling driven by downward turbulent diffusion of heat, or wind-driven upwelling in the Southern Ocean associated with the absence of a Drake Passage gap (Toggweiler and Samuels, 1995). The choice of numerical model parameters could influence the relative importance of each mechanism, and potentially the overturning response to temperature gradients.…”

Section: Introductionmentioning

confidence: 99%

The effect of low ancient greenhouse climate temperature gradients on the ocean's overturning circulation

Sijp

England

2016

Clim. Past

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Abstract. We examine whether the reduced meridional temperature gradients of past greenhouse climates might have reduced oceanic overturning, leading to a more quiescent subsurface ocean. A substantial reduction of the pole-toEquator temperature difference is achieved in a coupled climate model via an altered radiative balance in the atmosphere. Contrary to expectations, we find that the meridional overturning circulation and deep ocean kinetic energy remain relatively unaffected. Reducing the wind strength also has remarkably little effect on the overturning. Instead, overturning strength depends on deep ocean density gradients, which remain relatively unaffected by the surface changes, despite an overall decrease in ocean density. Ocean poleward heat transport is significantly reduced only in the Northern Hemisphere, as now the circulation operates across a reduced temperature gradient, suggesting a sensitivity of Northern Hemisphere heat transport in greenhouse climates to the overturning circulation. These results indicate that climate models of the greenhouse climate during the Cretaceous and early Paleogene may yield a reasonable overturning circulation, despite failing to fully reproduce the extremely reduced temperature gradients of those time periods.

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“…Sarmiento and Toggweiler, 1984;Siegenthaler and Wenk, 1984;Walker and Kasting, 1992;Toggweiler, 1999;Stephens and Keeling, 2000;Köhler et al, 2005;Peacock et al, 2006). However, less studies have coupled a genuine sediment model to the ocean box model (e.g.…”

Section: Introductionmentioning

confidence: 99%

LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

2012

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Abstract. The LOSCAR model is designed to efficiently compute the partitioning of carbon between ocean, atmosphere, and sediments on time scales ranging from centuries to millions of years. While a variety of computationally inexpensive carbon cycle models are already available, many are missing a critical sediment component, which is indispensable for long-term integrations. One of LOSCAR's strengths is the coupling of ocean-atmosphere routines to a computationally efficient sediment module. This allows, for instance, adequate computation of CaCO 3 dissolution, calcite compensation, and long-term carbon cycle fluxes, including weathering of carbonate and silicate rocks. The ocean component includes various biogeochemical tracers such as total carbon, alkalinity, phosphate, oxygen, and stable carbon isotopes. LOSCAR's configuration of ocean geometry is flexible and allows for easy switching between modern and paleo-versions. We have previously published applications of the model tackling future projections of ocean chemistry and weathering, pCO 2 sensitivity to carbon cycle perturbations throughout the Cenozoic, and carbon/calcium cycling during the Paleocene-Eocene Thermal Maximum. The focus of the present contribution is the detailed description of the model including numerical architecture, processes and parameterizations, tuning, and examples of input and output. Typical CPU integration times of LOSCAR are of order seconds for several thousand model years on current standard desktop machines. The LOSCAR source code in C can be obtained from the author by sending a request to loscar.model@gmail.com.

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Neodymium isotopic reconstruction of late Paleocene–early Eocene thermohaline circulation

Cited by 175 publications

References 51 publications

Bolide summer: The Paleocene/Eocene thermal maximum as a response to an extraterrestrial trigger

Bolide summer: The Paleocene/Eocene thermal maximum as a response to an extraterrestrial trigger

The effect of low ancient greenhouse climate temperature gradients on the ocean's overturning circulation

LOSCAR: Long-term Ocean-atmosphere-Sediment CArbon cycle Reservoir Model v2.0.4

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