Inherent characteristics of sawtooth cycles can explain different glacial periodicities

Omta, Anne Willem; Kooi, Bob W.; Voorn, G.A.K. van; Rickaby, Rosalind E. M.; Follows, Michael J.

doi:10.1007/s00382-015-2598-x

Cited by 13 publications

(50 citation statements)

References 66 publications

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“…The multibox model was modified from an earlier version used in Omta et al (2013Omta et al ( , 2016. The initial tracer concentrations are listed in Table A1, along with their respective values at the end of the spin-up.…”

Section: Appendix A: Multibox Setupmentioning

confidence: 99%

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO₂

Omta

Ferrari

McGee

2018

Global Biogeochemical Cycles

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The deep‐ocean carbonate ion concentration impacts the fraction of the marine calcium carbonate production that is buried in sediments. This gives rise to the carbonate compensation feedback, which is thought to restore the deep‐ocean carbonate ion concentration on multimillennial timescales. We formulate an analytical framework to investigate the impact of carbonate compensation under various changes in the carbon cycle relevant for anthropogenic change and glacial cycles. Using this framework, we show that carbonate compensation amplifies by 15–20% changes in atmospheric CO2 resulting from a redistribution of carbon between the atmosphere and ocean (e.g., due to changes in temperature, salinity, or nutrient utilization). A counterintuitive result emerges when the impact of organic matter burial in the ocean is examined. The organic matter burial first leads to a slight decrease in atmospheric CO2 and an increase in the deep‐ocean carbonate ion concentration. Subsequently, enhanced calcium carbonate burial leads to outgassing of carbon from the ocean to the atmosphere, which is quantified by our framework. Results from simulations with a multibox model including the minor acids and bases important for the ocean‐atmosphere exchange of carbon are consistent with our analytical predictions. We discuss the potential role of carbonate compensation in glacial‐interglacial cycles as an example of how our theoretical framework may be applied.

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Section: Appendix A: Multibox Setupmentioning

confidence: 99%

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO₂

Omta

Ferrari

McGee

2018

Global Biogeochemical Cycles

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“…First, a detailed discussion of the timing of CO 2 and the benthic isotopic record leaves open the possibility that at the timescale of the glacial-interglacial cycle the CO 2 simply acts as a feedback on ice volume (Ruddiman, 2006), even if it is also observed that the dynamics of the deglaciation are complex and that CO 2 changes can go through fairly abrupt dynamics (Ganopolski and Roche, 2009). On the other hand, other potential elements in the Earth system could generate nonlinearities yielding 100 kyr cycles: Ashkenazy and Tziperman (2004) proposed a "seaice switch", Imbrie et al (2011) interpret the nonlinear terms of their models as a representation of ice-sheet instability, Ellis and Palmer (2016) consider a dust albedo feedback, and Omta et al (2016) invoke an instability of the carbonate cycle. There is a plethora of possible mechanisms, but the mathematical expression of these various mechanisms is scarcely firmly constrained.…”

Section: Introductionmentioning

confidence: 99%

A theory of Pleistocene glacial rhythmicity

2018

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Abstract. Variations in Northern Hemisphere ice volume over the past 3 million years have been described in numerous studies and well documented. These studies depict the mid-Pleistocene transition from 40 kyr oscillations of global ice to predominantly 100 kyr oscillations around 1 million years ago. It is generally accepted to attribute the 40 kyr period to astronomical forcing and to attribute the transition to the 100 kyr mode to a phenomenon caused by a slow trend, which around the mid-Pleistocene enabled the manifestation of nonlinear processes. However, both the physical nature of this nonlinearity and its interpretation in terms of dynamical systems theory are debated. Here, we show that ice-sheet physics coupled with a linear climate temperature feedback conceal enough dynamics to satisfactorily explain the system response over the full Pleistocene. There is no need, a priori, to call for a nonlinear response of the carbon cycle. Without astronomical forcing, the obtained dynamical system evolves to equilibrium. When it is astronomically forced, depending on the values of the parameters involved, the system is capable of producing different modes of nonlinearity and consequently different periods of rhythmicity. The crucial factor that defines a specific mode of system response is the relative intensity of glaciation (negative) and climate temperature (positive) feedbacks. To measure this factor, we introduce a dimensionless variability number, V. When positive feedback is weak (V∼0), the system exhibits fluctuations with dominating periods of about 40 kyr which is in fact a combination of a doubled precession period and (to smaller extent) obliquity period. When positive feedback increases (V∼0.75), the system evolves with a roughly 100 kyr period due to a doubled obliquity period. If positive feedback increases further (V∼0.95), the system produces fluctuations of about 400 kyr. When the V number is gradually increased from its low early Pleistocene values to its late Pleistocene value of V∼0.75, the system reproduces the mid-Pleistocene transition from mostly 40 kyr fluctuations to a 100 kyr period rhythmicity. Since the V number is a combination of multiple parameters, it implies that multiple scenarios are possible to account for the mid-Pleistocene transition. Thus, our theory is capable of explaining all major features of the Pleistocene climate, such as the mostly 40 kyr fluctuations of the early Pleistocene, a transition from an early Pleistocene type of nonlinear regime to a late Pleistocene type of nonlinear regime, and the 100 kyr fluctuations of the late Pleistocene. When the dynamical climate system is expanded to include Antarctic glaciation, it becomes apparent that climate temperature positive feedback (or its absence) plays a crucial role in the Southern Hemisphere as well. While the Northern Hemisphere insolation impact is amplified by the outside-of-glacier climate and eventually affects Antarctic surface and basal temperatures, the Antarctic ice-sheet area of glaciation is limited by the area of the Antarctic continent, and therefore it cannot engage in strong positive climate feedback. This may serve as a plausible explanation for the synchronous response of the Northern and Southern Hemisphere to Northern Hemisphere insolation variations. Given that the V number is dimensionless, we consider that this model could be used as a framework to investigate other physics that may possibly be involved in producing ice ages. In such a case, the equation currently representing climate temperature would describe some other climate component of interest, and as long as this component is capable of producing an appropriate V number, it may perhaps be considered a feasible candidate.

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“…Some mechanisms rely on a bifurcation occurring in the unforced climate system which fundamentally changes how the system operates (Ashwin and Ditlevsen, 2015;Ditlevsen, 2009;Huybers and Langmuir, 2017;Maasch and Salzman, 1990;Tziperman and Gildor, 2003). Other mechanisms invoke a "spontaneous" change, such as a shift between attractors due to subtle changes in insolation (Omta et al, 2015 Fig. 1 a) The LR04 stack of normalised isotopic oxygen anomalies in deep ocean sediment cores -a proxy for global ice volume and deep ocean temperatures (Lisiecki and Raymo, 2005).…”

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The middle Pleistocene transition by frequency locking and slow ramping of internal period

Nyman

Ditlevsen

2019

Clim Dyn

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The increase in glacial cycle length from approximately 41 to on average 100 thousand years around 1 million years ago, called the Middle Pleistocene Transition (MPT), lacks a conclusive explanation. We describe a dynamical mechanism which we call Ramping with Frequency Locking (RFL), that explains the transition by an interaction between the internal period of a self-sustained oscillator and forcing that contains periodic components. This mechanism naturally explains the abrupt increase in cycle length from approximately 40 to 80 thousand years observed in proxy data, unlike some previously proposed mechanisms for the MPT. A rapid increase in durations can be produced by a rapid change in an external parameter, but this assumes rather than explains the abruptness. In contrast, models relying on frequency locking can produce a rapid change in durations assuming only a slow change in an external parameter. We propose a scheme for detecting RFL in complex, computationally expensive models, and motivate the search for climate variables that can gradually increase the internal period of the glacial cycles.

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Inherent characteristics of sawtooth cycles can explain different glacial periodicities

Cited by 13 publications

References 66 publications

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO₂

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO₂

A theory of Pleistocene glacial rhythmicity

The middle Pleistocene transition by frequency locking and slow ramping of internal period

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Inherent characteristics of sawtooth cycles can explain different glacial periodicities

Cited by 13 publications

References 66 publications

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO2

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO2

A theory of Pleistocene glacial rhythmicity

The middle Pleistocene transition by frequency locking and slow ramping of internal period

Contact Info

Product

Resources

About

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO₂

An Analytical Framework for the Steady State Impact of Carbonate Compensation on Atmospheric CO₂