Neoproterozoic ‘snowball Earth’ simulations with a coupled climate/ice-sheet model

Hyde, William F.; Crowley, Thomas J.; Baum, Steven K.; Peltier, W. R.

doi:10.1038/35013005

Cited by 422 publications

(335 citation statements)

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“…The ''white-Earth'' instability (25) therefore may not have been fully realizable. Glaciations may have advanced near but not entirely to the equator (26).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of the Neoproterozoic carbon cycle

Rothman

Hayes

Summons³

2003

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

519

336

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The existence of unusually large fluctuations in the Neoproterozoic (1,000 -543 million years ago) carbon-isotopic record implies strong perturbations to the Earth's carbon cycle. To analyze these fluctuations, we examine records of both the isotopic content of carbonate carbon and the fractionation between carbonate and marine organic carbon. Together, these are inconsistent with conventional, steady-state models of the carbon cycle. The records can be well understood, however, as deriving from the nonsteady dynamics of two reactive pools of carbon. The lack of a steady state is traced to an unusually large oceanic reservoir of organic carbon. We suggest that the most significant of the Neoproterozoic negative carbon-isotopic excursions resulted from increased remineralization of this reservoir. The terminal event, at the ProterozoicCambrian boundary, signals the final diminution of the reservoir, a process that was likely initiated by evolutionary innovations that increased export of organic matter to the deep sea.T he coevolution of the biosphere and geosphere is reflected in large part by changes in the long-term carbon cycle (1). Past changes within the cycle are recorded in the isotopic content of carbonate and organic carbon buried in ancient sediments (2). Extraordinarily large fluctuations occur in the Neoproterozoic [1,000-543 million years ago (Ma)] carbon-isotopic record both immediately preceding the Cambrian diversification of complex animal life (3-5) and in the Ϸ200 million years before it (6). There is much interest in determining not only the cause of these isotopic events (3-9) but how, if at all, they are related to early animal evolution (10).Here we analyze a significant portion of the Neoproterozoic isotopic record by portraying it as a dynamical trajectory in a two-dimensional space indexed by the isotopic content of carbonate carbon and the fractionation between carbonate and marine organic carbon. This depiction, analogous to the construction of phase portraits in dynamical systems theory (11), provides specific predictions for a carbon cycle evolving quasistatically in a succession of steady states. We find that the Cenozoic portion (0-65 Ma) of the carbon-isotopic record satisfies these predictions; however, the Neoproterozoic record does not.The dynamics of a system with two sizeable and isotopically distinct pools of reactive carbon suffice to explain the Neoproterozoic records. Then as now one pool was oceanic and atmospheric CO 2 . Here we show that the other was probably oceanic organic carbon. The isotopic data indicate that this reservoir was large and that its average properties changed slowly. However, fluctuations in its size would have led to major variations in the isotopic record. Moreover, even if the size of the organic reservoir had been perfectly constant, changes in the fractionation associated with organic production would have led to isotopic fluctuations much greater than those predicted by steady-state theory.The fluctuations of greatest interest are those associ...

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“…The ''white-Earth'' instability (25) therefore may not have been fully realizable. Glaciations may have advanced near but not entirely to the equator (26).…”

Section: Discussionmentioning

confidence: 99%

Dynamics of the Neoproterozoic carbon cycle

Rothman

Hayes

Summons³

2003

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

519

336

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“…The model of the Slushball Earth by Hyde et al (2000), or similar, postulating circum-equatorial areas of open water and access to a coastal zone with a sea floor substrate, would provide sufficiently robust environments for photosynthetic benthic cyanobacteria and pelagic phytoplankton and for early metazoans without any extreme adaptations.…”

Section: Discussionmentioning

confidence: 99%

New records of late Ediacaran microbiota from Poland

Moczydłowska

2008

Precambrian Research

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a b s t r a c tNew records of organic-walled microfossils, including cyanobacteria, phytoplankton (certain acritarchs) and some microbiota of unknown biological affinities, are reported from the late Ediacaran Włodawa Formation in the Łopiennik IG-1 borehole, Poland. The microfossil association consists mostly of known species, which originated prior to the Cryogenian Period, evidence that these microorganisms survived the Neoproterozoic glacial epochs. The longevity of most of the species is extended herein to ca. 545 Ma. One species is new but described as gen. et sp. indet., because only a single specimen is available. Although the microfossils represent both prokaryotic and eukaryotic groups of organisms, and benthic and planktic modes of life, all, with the exception of Valkyria, are photoautotrophic aerobes. Metabolic processes of nutrition, respiration and reproductive cycles, and ecologic habitats of these biota and the evolutionary lineages to which they belong are analyzed with respect to the basic requirements needed to survive prolonged periods of environmental perturbation.All recorded here cyanobacteria are benthic microbial mat-dwellers, requiring ample water and regular oxygen supply and sun light for their metabolism. Planktic species of Leiosphaeridia studied here are considered to be green algae (chlorophyceans), forming resting cysts and alternating sexual/vegetative generations in their life cycle. They also required habitats of well-oxygenated open water in the photic zone and periodic access to bottom sediment (to rest the cyst) in order to survive the glacial epochs, as they evidently did. It is argued that the natural habitats of all these biota must have been preserved and ecologically functional throughout the Cryogenian Period, and have been robust enough to sustain viable populations and genetic stocks of at least some evolutionary lineages known at the time. This is a primary constraint imposed by contemporaneous marine biosphere on the Earth System model, which can be accepted among hypothetical versions of the Snowball Earth hypotheses based on sedimentological, geochemical, physical and other geological records. The Slushball Earth model, or comparable, is thus favoured over strict Snowball Earth model because it reconciles the habitable conditions with other envisaged geo-and physical conditions during the period.

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“…It is believed, for example, that Earth has on occasion (∼710 Ma, ∼635 Ma, and possibly at other times) fallen into a snowball state, during which global oceans completely (Kirschvink 1992;Hoffman et al 1998) or nearly completely (Hyde et al 2000;) froze over. As a limiting case, we will be considering here a planet with entirely icecovered oceans.…”

Section: Snowball Climatementioning

confidence: 99%

Thermal Phases of Earth-Like Planets: Estimating Thermal Inertia From Eccentricity, Obliquity, and Diurnal Forcing

Cowan

Voigt

Abbot

2012

ApJ

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In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer would measure peak-to-trough amplitudes of 13% and 47% for the temperate and snowball climates, respectively. Diurnal heating is important for equatorial observers (∼5% phase variations), because the obliquity effects cancel to first order from that vantage. Finally, we compare the prospects of optical versus thermal direct imaging missions for constraining the climate on exoplanets and conclude that while zero-and one-dimensional models are best served by thermal measurements, second-order models accounting for seasons and planetary thermal inertia would require both optical and thermal observations.

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Neoproterozoic ‘snowball Earth’ simulations with a coupled climate/ice-sheet model

Cited by 422 publications

References 40 publications

Dynamics of the Neoproterozoic carbon cycle

Dynamics of the Neoproterozoic carbon cycle

New records of late Ediacaran microbiota from Poland

Thermal Phases of Earth-Like Planets: Estimating Thermal Inertia From Eccentricity, Obliquity, and Diurnal Forcing

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